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2020, 41(21): 0-0.  
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Research and Investigation
Mechanism of the Effect of Lactate on the Structure of Myoglobin in the in Vitro Hatching Model
LI Bing-zi, WEI Hong-yan, LEI Yun, CHEN Cheng, ZHANG Yu-bin
2020, 41(21): 1-7,14.   doi: 10.13386/j.issn1002-0306.2020020148
Abstract(47) PDF(14)
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In order to study the interaction mechanism between lactate and myoglobin(Mb)heme prosthetic group,the longissimus dorsi was used as the raw material. Mb was separated and purified before adding calcium lactate. It was stored at 4 ℃ for 0,12,24,36,and 72 h,using ultraviolet-visible absorption spectrum,fluorescence spectrum and circular dichroism spectrum to determine the absorbance of the characteristic peak. The results showed that the absorption intensity of the ultraviolet-visible spectrum at the characteristic peak of 409 nm at four time points during refrigeration was slightly increased,but the peak position and peak shape barely changed;the intensity of the emission peak of the fluorescence spectrum at 597 nm weakened. The position of the emission peak of the porphyrin ring of Mb did not shift,but the fluorescence intensity weakened with the extension of storage time;circular dichroism chromatography showed that the shape and shoulder of the three characteristic peaks in the far ultraviolet region of 192,208 and 222 nm in the control and treatment groups The position of the peak did not change significantly,and the pattern at 190~240 nm in the calcium lactate treatment group was smooth like the control group. It shows that the covalent addition of lactate and Mb does not occur on the heme prosthetic group,but regulates myoglobin through non-heme ligand binding.

Structural Elucidation and Antioxidant Activity of LRP-Ⅰ and LRP-Ⅱ Polysaccharide from Leccinum rugosiceps
WU Yan, XU Feng, LI Xiao-shuang, ZHU Jia-hao, SHEN Li-qun
2020, 41(21): 8-14.   doi: 10.13386/j.issn1002-0306.2020020061
Abstract(15) PDF(1)
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Two main polysaccharide fractions(LRP-Ⅰ and LRP-Ⅱ)were isolated from Leccinum rugosiceps fruit by hot water extraction. The structural characterstics of LRP-Ⅰ and LRP-Ⅱ were elucidated by chromatographic methods,and the difference of antioxidant activity between the two polysaccharides was also evaluated in this paper. Infrared spectromete(IR)showed that LRP-Ⅰ and LRP-Ⅱ were α-pyranohexose with characteristic peaks of polysaccharides. The monosaccharide compositionwas determined by high performance liquid chromatography(HPLC),LRP-Ⅰ mainly consisted of mannose,rhamnose,glucose,xylose and fructose in a molar ratio of 0.68:0.10:2.87:0.28:0.12,and LRP-Ⅱ was mainly composed of mannose,glucose,xylose,alabinoseand fructose in a molar ratio of 1.69:2.30:2.06:0.10:1.04. The average molecular weights of LRP-Ⅰ and LRP-Ⅱ respectively were 1.98×104 Da and 8.38×106 Da by high performance gel-permeation chromatography(HPGPC).The methylated derivatives were analyzed by gas chromatography-mass spectrometer(GC-MS),the results suggested that→1,4)-Glcp,→1,3)-Manp and →1,3)-Xylp bond types existed in the both of LRP-Ⅰ and LRP-Ⅱ molecules.The scanning electron microscope(SEM)illustrated that scattered flaky,banded and filiformpolysaccharide existed in LRP-Ⅰ,differently reticular structure dominated in LRP-Ⅱ. In the content of 1~10 mg/mL,antioxidant experiments demonstrated that both of LRP-Ⅰ and LRP-Ⅱ showed the good scavenging effects on ABTS radical and DPPH radical,especially LRP-Ⅰ was slightly stronger in scavenging rate than that of LRP-Ⅱ. This study provides a reference for further understanding the polysaccharide activity mechanism of Leccinum rugosiceps.

Effects of Different Storage Temperatures on Physico-Chemical Characteristics and Flavor Changes of Ultra Pasteurized Milk
YI Sheng-nan, ZHANG Shu-wen, LU Jing, PANG Xiao-yang, SONG Hui-min, LIANG Jia-qi, HAO Li-yu, HU Cheng, XU Xiao-xi, LV Jia-ping
2020, 41(21): 15-20,28.   doi: 10.13386/j.issn1002-0306.2019080175
Abstract(19) PDF(2)
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In this experiment,fresh milk was homogenized and then heat-treated at 120 ℃ for 15 s,followed by aseptic filling. Preservation experiments were performed at storage temperatures of 4,25,and 37 ℃ for 45 days to analyze the physical-chemical and flavor changes of the products during storage. The results showed that the protease activity of bacteria and lipase activity of the ultra pasteurized milk changed not significantly under the storage condition of 4 ℃,and the protease activity increased sharply after 25 days at 37 ℃ storage conditions,and reached the maximum value of 3.2 U/mL on the 45th day. The lipase activity at the storage temperature of 37 ℃ all increased sharply after the 10th day of storage,and the vitality was maintained at about 6.25 and 6.75 U/mL,respectively. In addition,during storage,the pH decreased,the particle size increased,and the Zeta potential first decreased and then increased. As the storage temperature increased,the rate of change accelerated,and there were significant differences between samples at different storage temperatures. Regarding color and luster,the ultra-pasteurized milk under 4 ℃ preservation only had significant changes in L* value,and the other two temperatures had significant changes in L*,a*,and b* values. The results of electronic nose and electronic tongue showed that there was no significant difference in the odor and taste of ultra pasteurized milk during storage at 4 ℃,but the odor and taste were significantly different at 25 and 37 ℃. The results showed that the shelf life of ultra pasteurized milk could reach 45 days at a storage temperature of 4 ℃,while the shelf life of ultra pasteurized milk couldn’t reach 45 days at 25 and 37 ℃.

Quality Improvement and Structural Characteristics of Wheat Bran by Microwave Enzymatic Method
LV Chun-yue, YANG Qing-yu, LIU Lu, LI Rui-zhi, LUO Zhi-gang, ZHANG Hong-wei, WANG Yan-wen, ZHANG Yi-rui, XIAO Zhi-gang
2020, 41(21): 21-28.   doi: 10.13386/j.issn1002-0306.2020020310
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Using wheat bran as raw material,orthogonal experiment was used to optimize the technological parameters of microwave combined enzymatic hydrolysis to improve the quality of wheat bran,and the effects of microwave,enzymatic hydrolysis and microwave combined enzymatic hydrolysis on the structure and properties of wheat bran were analyzed.The study found that,wheat bran microwave combined enzymatic hydrolysis of the optimal technological parameters were:microwave power 700 W,time 15 min,ratio of material to water 1:4,xylanase added amount 0.4 g,cellulase added amount 0.4 g,enzymatic hydrolysis time 4 h,enzymatic hydrolysis temperature 60 ℃,at this time the reducing sugar content in wheat bran was 25.15 mg/mL.After microwave enzymolysis,water holding capacity of wheat bran increased by 30.18%,phytic acid content decreased by 70.46%,oil holding capacity decreased by 26.69%,lipase(LA)residual enzyme activity decreased to 6.13%,crude fiber content decreased to 2.79%,and reducing sugar content increased to 25.15 mg/mL.The results of FTIR showed that microwave enzymatic hydrolysis could break the glycoside bonds between the molecules,degrade cellulose and hemicellulose in the cell wall of wheat bran,and produce small reducing sugars.The results of scanning electron microscope showed that microwave combined with enzymatic hydrolysis destroyed the structure of wheat bran,making the surface of wheat bran rough,loose and porous.The lipase residual activity in modified wheat bran was significantly decreased and the edible quality of wheat bran was significantly improved.

Preparation Technology Optimization of Soluble Dietary Fiber and Its Structure Characterization and Composition of Monosaccharide from Clausena lansium Sarcocarp
WEN Pan, PEI Zhi-sheng, ZHU Ting-ting, YU Zi-juan, GENG Yu-kun, CHEN Cai-yu, XUE Chang-feng
2020, 41(21): 29-36.   doi: 10.13386/j.issn1002-0306.2020020124
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The ultrasonic microwave assisted enzymatic extraction of soluble dietary fiber(SDF)from seedless of Clausena lansium sarcocarp was optimized by response surface methodology.The physicochemical properties,monosaccharide composition and microstructure of SDF were studied. The results showed that the optimal preparation conditions of SDF were as follows:The ratio of material to liquid was 1:23 g/mL,ultrasonic time was 25 min,ultrasonic power was 280 W,and cellulase dosage was 0.64%. Under these conditions,the yield of SDF was 12.55%,the purity was 79.65 g/100 g,the net yield was 10.00%,the water holding capacity was 6.04 g/g,the oil holding capacity was 1.58 g/g,and the swellability was 39.25 mL/g. Infrared spectrum scanning showed that SDF of Clausena lansium sarcocarp had typical polysaccharide characteristics. Saccharonitrile-derived gas chromatography showed that SDF contained 4 kinds of monosaccharides,including arabinose,glucose,galactose,and mannose.The molar ratios were 12:7.5:3:1. Scanning electron microscopy showed that the SDF of Clausena lansium sarcocarp was compact and smooth folded. The research results could provide a reference for the development and utilization of SDF from Clausena lansium sarcocarp.

Degradation Efficiency and Pathway of Malathion Treated by High Voltage Electric Field Cold Plasma
CONG Lai-xin, HUANG Ming-ming, ZHANG Jian-hao, YAN Wen-jing
2020, 41(21): 37-42,47.   doi: 10.13386/j.issn1002-0306.2019120131
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The degradation efficiency of malathion by high voltage electric field cold plasma was studied by using the high-voltage electric field voltage intensity,treatment time and initial concentration of pesticide as experimental parameters. Gas chromatographic(GC)was used to determine the residue of malathion and a degradation kinetic model was established. Gas chromatography tandem mass spectrometry(GC-MS)was used to identify malathion degradation products. Combined with Fourier transform infrared spectros’copy(FT-IR),the degradation efficiency of malathion by cold plasma was studied and its degradation pathway was analyzed. The results showed that the degradation efficiency of malathion in water significantly increased with the increase of cold plasma voltage intensity and treatment time(P<0.05). When the initial concentration was 0.1 μg/mL,the degradation efficiency of malathion reached 79.62%±2.97% by the treatment of 50 Hz,80 kV for 180 s. The degradation products were malaoxon,triethyl phosphate,2-butenedioic acid(Z)-,diethyl ester,2-butenedioic acid(E)-,diethyl ester,O,O,S-trimethyl phosphorodithioate and 2-dimethoxyphosphinothioylsulfanyl-4-ethoxy-4-oxobutanoic acid. Malathion could be degraded into triethyl phosphate with lower toxicity by further processing. And the formation of intermediates in the degradation of malathion mainly by two pathways of oxidation of P=S bond and fracture of C-S bond. The study provides a new method for the study of degradation of pesticide residues in water.

Isolation and Identification of the Constituents of Extracts by Different Polar Solvents of the Edible Fungus “Shuipizi”
ZHANG Fang-ya, BAO Hai-ying, BAU Tolgor
2020, 41(21): 43-47.   doi: 10.13386/j.issn1002-0306.2019120098
Abstract(8) PDF(1)
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The purpose of this study was to analyse the chemical constituents of the traditional edible fungi of "Shuipizi"(Clitocybe phyllophila(Pers.)P. Kumm.)from mount wutai. The 10 chemical constituents were separated and obtained by gel and silica column chromatography methods after solvent extraction. By the modern chromatographic techniques,spectroscopy and chemical methods,the chemical constituents were analyzed and identified as:Dibutyl phthalate(1),hexadecanoic acid(2),ergosterol(3),ergosterol peroxide(4),stearic acid(5),benzoic acid(6),urea(7),ergosta-7,22-diene-3β,5α,6β-triol(8),betulin(9),nicotinic acid(10). All the 10 compounds were isolated from Clitocybe phyllophila for the first time.

Degradation Kinetics of Verbascoside at Different Temperature,pH and Light
ZHANG A-xi, LIAN Ying-zhu, SHEN Yue-feng, FU Gui-ming, WAN Yin
2020, 41(21): 48-52,66.   doi: 10.13386/j.issn1002-0306.2020020171
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In order to study the stability(the thermal,light and pH stability)of verbascoside,this paper discussed the effects of temperature(37,50,60,80,100 ℃),pH(2,6,7,8)and light on the degradation kinetics of verbascoside by HPLC. The results showed that the degradation reaction of verbascoside in different temperature,pH and light/dark conditions belonged to the first order reaction. The results showed that high temperature(above 60 ℃),near neutral environment(pH6~8)and light were not conducive to the preservation of verbascoside. The half-life of verbascoside was more stable at medium low temperature(37,50 ℃),low pH(2)and dark conditions,and the half-life was significantly prolonged. In this paper,the main factors affecting the stability of verbascoside were analyzed,which could provide an important reference for the extraction,purification and activity analysis of verbascoside.

Effects of Five Proteases on the Taste Characteristics of Oyster Hydrolysates
YANG Zhao, YAO Yu-jing, HUANG Jia-jia, LIANG Zhi-li, LIANG Rui-jin, CHEN Li-shan, LIANG Jian-ping
2020, 41(21): 53-57,66.   doi: 10.13386/j.issn1002-0306.2019080172
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Oyster was taken as the research object,under the condition of the same degree of hydrolysis,the effects of trypsin,animal protease,alkaline protease,neutral protease and flavor protease on the sensory,peptide molecular weight and free amino acid of oyster hydrolysate were studied. The results showed that the five hydrolysates all had strong umami flavor. The whole sensory evaluation of alkaline protease hydrolysates was the best among the five hydrolysates. The percentage of peptide area with molecular weight less than 5 kDa was trypsin(74.99%),animal protease(73.44%),neutral protease(71.53%),alkaline protease(68.46%)and flavor protease(58.77%). The percentage of free amino acids was the highest in glutamic acid and the lowest in histidine. The total content of free amino acids from high to low were trypsin(22.816 mg/g),neutral protease(20.775 mg/g),flavor protease(20.530 mg/g),animal protease(16.287 mg/g)and alkaline protease(16.232 mg/g). The number of free amino acids with a TAV greater than 1 in trypsin,animal protease,alkaline protease,neutral protease and flavor protease was 10,8,8,9 and 11 respectively. Among the five hydrolysates,the amino acid with the largest TVA value was glutamic acid.

Effects of Far-infrared Assisted Hot Air Drying on the Drying Characteristics and Quality of Saury Fillets
CAI Jie, LI Bian-sheng, RUAN Zheng
2020, 41(21): 58-66.   doi: 10.13386/j.issn1002-0306.2020020141
Abstract(5) PDF(2)
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In order to investigate the influence of far-infrared assisted hot air drying on the drying characteristics and quality of saury fillets,the far-infrared assisted hot air drying and hot air drying processes were used to dehydrate saury fillets at 50,60,70,80 and 90 ℃,and the quality changes were observed. The results showed that in order to reduce the dry base moisture content of saury fillets to below 43%,the drying time required for hot air drying at 50 to 90 ℃ was 570,435,282,225 and 208 min,respectively,and the time required for far-infrared assisted hot air drying was 510,395,258,204 and 186 min. Increasing the drying temperature was beneficial to shorten the drying time and increase the drying rate,and the far-infrared assisted hot air drying had obvious drying advantages. Low-field nuclear magnetic resonance test results showed that the hard-to-flow water in the saury fillets was converted into free water and diffused outwards to achieve the purpose of drying. In terms of drying quality,the a* values and b* values of saury fillets increased to 4.85~8.98 and 12.08~16.01 respectively after drying. With the increase of drying temperature,texture indexes such as hardness,chewability and recovery,and the sensory score of umami,odor and chewability showed an upward trend,the L* value,TBA value and sensory score of tissue morphology showed a downward trend,while the color scores showed an upward trend and then a downward trend. Compared with hot air drying,far-infrared assisted hot air drying saury fillets had better quality in color and texture characteristics,and higher sensory scores in tissue morphology and odor,but there was no significance difference between two drying methods in TBA value(P>0.05).

Application of Microencapsulation Technology in Ice Cream with Probiotic CICC 6075
TIAN Wen-jing, ZHAO Dong-rui, SUN Yu-qing, LIU Qing, LUO Hong-xia, DENG Zhi-feng, WANG Hui-hua
2020, 41(21): 67-74.   doi: 10.13386/j.issn1002-0306.2019120324
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To explore the feasibility of microcapsule technology in ice cream production,Lactobacillus acidophilus CICC 6075 microcapsules were prepared by emulsification with lactoprotein as the wall material. In this experiment,the effects of microcapsules(group C)and naked probiotics(group B)on the physical and chemical properties and sensory properties of ice cream were investigated by using ice cream without probiotics(group A)as blank control. As the results showed,neither the addition of naked Lactobacillus acidophilus CICC 6075 nor microcapsule had significant effect on the properties of ice cream. However,during the processing and storage of ice cream,microcapsules provided good protection for CICC 6075 due to their dense structure,which significantly increased the number of viable bacteria of CICC 6075.The number of viable CICC 6075 in group B decreased(1.20±0.08)lg CFU/g during stirring and freezing,while the number of viable CICC 6075 only reduced(0.09±0.07)lg CFU/g in group C. After storage at-18 ℃ for 150 d,the number of viable CICC 6075 decreased to(5.54±0.03)lg CFU/g in group B,lower than the minimum threshold for probiotics to play their health benefits. While group C only decreased(0.60±0.08)lg CFU/g,and the final viable count was as high as(8.09±0.03)lg CFU/g. In addition,it was also found in digestive characteristics test that the gastric acid tolerance and adhesion of CICC 6075 to epithelial cells of small intestinal significantly decreased in group B(6.16%±0.04%,16.76%±0.05%)during the low temperature storage of 150 d,and were significantly higher than those of group C(1.92%±0.07%,4.47%±0.09%). In conclusion,microcapsule technology could significantly improve the resistance of probiotics to adverse environments(such as low temperature and gastric juice)during the processing and storage of ice cream,so it could not only guarantee the good quality and characteristics of ice cream,but also improve its functional activity,which had a certain application prospect.

Application of Pea Protein Isolate-Carboxymethylcellulose Complex in Emulsions
PANG Shu-jie, LI Na-na, REN Si, LIU Li-ya, TONG Li-tao, WANG Li-li, ZHOU Xian-rong, ZHOU Su-mei
2020, 41(21): 75-80.   doi: 10.13386/j.issn1002-0306.2020030316
Abstract(4) PDF(1)
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For the purpose of improving the application character of pea protein isolate(PPI)emulsions at acidic conditions,the emulsions oil-in-water(O/W)was stabilized by complex at acidic conditions,the complex was informed by interactions between PPI and carboxymethylcellulose(CMC). Primarily,the solubility and surface hydrophobicity of PPI(3%)were studied with increasing of CMC concentration(0~0.5%). And on this basis,the effects of PPI-CMC complex were analyzed on the ζ-potential,droplet size,viscosity,turbiscan stability index(TSI)and microstructure of emulsions. The results showed that while CMC concentration increased from 0 to 0.5%,the negative surface charges of the emulsion droplets were strengthened for which the absolute values of ζ-potential increased. At CMC concentration ≥0.4%,the stability of the PPI emulsions was efficiently improved,the droplets dispersed evenly in the systems and the flocculation phenomenon was reduced. After storage at 4 ℃ for one week,no visible separations were found in these systems. Therefore,the application character of PPI emulsions at acidic conditions can be effectively improved by regulating PPI-CMC interaction and the results are expected to provide references for the development of high pea protein acid dairy and beverage.

Effects of Different Drying Methods on Physicochemical Properties and Antioxidant Activity of Dried Cabbage
WANG Hong-li, YU Zhi-fang
2020, 41(21): 81-86.   doi: 10.13386/j.issn1002-0306.2019120334
Abstract(4) PDF(1)
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In order to study the effects of different drying methods on physicochemical properties and antioxidant activity of cabbages,improve the quality of dried cabbage and increase the added value of cabbage,this experiment adopted 65 ℃ hot air drying,1 kW microwave drying and combined drying to treat cabbage,the color,VC,free phenol,total phenolics and antioxidant activity of dried cabbages were determinated,the eassay also made correlation analysis between antioxidant content and antioxidant activity. The results showed that,the combined dried cabbage had the best color and ΔE was 15.01±0.59. The contents of total phenol and free phenol in cabbage under different drying methods were significantly different(P<0.05),while the existing state of phenol changed little. Microwave dried cabbage exhibited higher VC,free phenol and total phenolics contents were 23.14 mg/100 g FW,80.22 and 124.85 mg GAE/100 g FW,respectively,the retention rates were 67.3%,90% and 86.6%,respectively. And its DPPH free radicals,ABTS radicals scavenging ability and Fe3+ reduction ability were the strongest. Correlation analysis showed that VC,phenols and antioxidant activities of cabbage under different drying methods were significantly correlated(P<0.05). Therefore,microwave drying method was better than hot air drying and combined drying and the existing drying production line could try to combine microwave drying technology to improve the quality of dried products.

Effects of Ultrasonic Treatment on Gel Rheological Properties and Gel Formation of Soybean Protein Isolate
LIU Ran, ZENG Qing-hua, WANG Zhen-yu, CHENG Shuang, MU Hong-jing, LIANG Rong
2020, 41(21): 87-92,98.   doi: 10.13386/j.issn1002-0306.2020020155
Abstract(6) PDF(1)
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Soybean protein isolate(SPI),used as the raw material,was treated by ultrasonic waves at different powers(100,200,400,600 and 800 W)to explore the effect of ultrasonic treatment on the gelling properties of SPI,while the small amplitude oscillatory shear mode of TA rheometer was utilized to further analyze the effect on the rheological properties and gel formation of SPI. The results showed that ultrasonic waves could not only reduce the storage modulus(G'),loss modulus(G″)and apparent viscosity but also changed the initial viscoelasticity of the SPI dispersing agent. The results of experiments simulating the thermal gel process of SPI showed that the ultrasonic treatment could change the gelling ability of SPL. Ultrasonic waves weakened the gel formation ability of SPI at low powers,and delayed the gel formation process at high powers. However,the use of medium-power(200~600 W)ultrasonic waves could significantly improve the gel performance and accelerate the gel formation of SPI. The ultrasonic treatment conducted at medium powers remarkably increased the viscoelastic property of the SPI gel,with the best effect obtained from the 400 W ultrasonic group,of which the resulting gel had the maximum G' and G″ as well as the minimum loss tangent(tanδ). Medium-power ultrasonic waves could change the initial viscoelastic structure of the SPI dispersing agent to increase the sites of hydrophobic interactions and hydrogen bonding during the formation of thermal gel,thus forming the gel with a three-dimensional net structure of higher strength and density. Ultimately,it can be concluded that ultrasonic waves at the appropriate power can enhance the gel performance of commercial SPI.

Protein Distribution Characteristics in Different Muscle Parts of Haliotis discus hannai
YIN Lei-li, ZHOU Fen, YAO Lin-yan, WANG Xi-chang
2020, 41(21): 93-98.   doi: 10.13386/j.issn1002-0306.2020020019
Abstract(6) PDF(1)
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In order to understand the raw material properties of abalone,the nutrient composition,protein composition and distribution of the three parts muscle (the adductor muscle,the transition muscle and the skirt muscle)from Haliotis discus hannai were analyzed and determined,and the tissue structure of the three parts muscles was observed by light microscope. The results showed that the water content of the adductor muscle was the lowest,while the crude protein and crude fat were the highest. It was found that the salt-soluble protein and non-protein nitrogen content were higher in the three parts muscles,and the content of water-soluble protein was the lowest. The content of matrix protein was about 2 times that of the transition muscle and 3 times that of the adductor muscle,the collagen content was rich in the skirt muscle. In SDS-PAGE analysis,the protein distribution of the adductor and the transition muscle was similar,and the protein composition was richer than that of the skirt muscle. The distribution of myofibrils and collagen fibers in the light microscope was consistent with the results of protein content determination,and the morphology of muscle fibers in cross section and longitudinal section of muscle fibers was different. Thus,the research results can provide theoretical reference and practical basis for the further processing and development of abalone.

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Bioengineering
The Response Mechanism of Klebsiella pneumoniae to H2O2 Oxidative Stress
QIU Xue-mei, XU Li, LUO Hai-Long, YUAN Jie, YANG Jing, LI Bei, WANG Jing-jie
2020, 41(21): 99-104.   doi: 10.13386/j.issn1002-0306.2020050357
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Objective:This study aimed at revealing the effect of host intestinal oxidative condition on Klebsiella pneumoniae and its mechanism of response to oxidative stress.Method:In vitro intestinal oxidative conditions,Klebsiella pneumoniae was inoculated in liquid medium containing different concentration of H2O2 for oxidative stress treatment,the growth curve of bacteria was measured,and the key virulence factors of bacteria--capsule and biofilm were examined. Furthermore,qRT-PCR quantitative analysis was used to analyze the differences in the expression of genes related to the phenotype of the capsule and biofilm. Results:The results showed that under condition of H2O2 oxidative stress,when it was in a lower concentration range(<1.56 mmol/L),the early growth stage of Klebsiella pneumoniae was inhibited,and it gradually adapted to stress in the middle and late stages,and the growth was not significantly affected. The production of Klebsiella pneumoniae capsule was significantly reduced with a dose-dependent effect;while under a certain concentration range of oxidative factors,the amount of biofilm formation increased. And molecular testing showed that the expression level of the capsular structure gene magA was significantly down-regulated,and the biofilm-related gene YbaJ was significantly up-regulated. Conclusions:Taken the results together,Klebsiella pneumoniae could up-regulate the expression of gene YbaJ to promote the formation of virulence factor biofilm in response to oxidative factor stress,which provided new ideas for the study of the interaction between Klebsiella pneumoniae and host intestinal factors and the pathogenic mechanism.

Optimization of Androstenedione Production by Free Cell Method Using Response Surface Methodology
LI Shi-chuang, CAI Shuai, GUO Qiu-shuang, ZHANG Ming-kai, LI Hua, LIU Yu-peng
2020, 41(21): 105-109,115.   doi: 10.13386/j.issn1002-0306.2020010138
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The process of using free cell method produce androstenedione was optimized by response surface methodology. First,the Plackett-Burman experimental design was used to screen out three main factors affecting yield:Phytosterol concentration,hydroxypropyl-β-cyclodextrin concentration,and bacterial cell amount. On this basis,the steepest climbing path method was used to approach the region of maximum response value. Finally,the response surface analysis method was used to determine the interaction between the main factors and the optimal conditions. The results showed that when the phytosterols concentration was 19.41 g/L,the hydroxypropyl-β-cyclodextrinconcentration was 80.14 g/L,the bacterial cell amount was 110.55 g/L,the maximum theoretical yield of androstenedione was 67.25%. After three parallel experiments,the actual average yield was close to the predicted yield.At this time,the androstenedione concentration reached 8.68 g/L,and the production intensity was 2.17 g/(L·d).

Expression and Thermal Stability Analysis of Shark Single Domain Antibody-Alkaline Phosphatase Fusion Protein
LIU Xin, QU Yue-kuan, CAO Li-min, SUI Jian-xin
2020, 41(21): 110-115.   doi: 10.13386/j.issn1002-0306.2020020051
Abstract(4) PDF(0)
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The stability of enzyme-labeled antibody plays an important role in enzyme-linked immunosorbent assay(ELISA),but the disadvantages in thermal stability of the conventional antibody-enzyme conjugation has restricted the application of enzyme-labeled antibodies in ELISA. In this study,the shark single domain antibody specific to myofibrillar-binding serine protease(MBSP)fused with alkaline phosphatase was expressed and its affinity and thermal stability were investigated. Results showed that when induced with Isopropyl-beta-D-thiogalactopyranoside(IPTG)at 16 ℃,the fusion protein which was about 63 kDa in molecular weight,which could be expressed in soluble with high affinity and thermal stability. The KD value of the fusion protein to MBSP could reach 7.80×10-8 mol/L and the binding activity of fusion protein could be kept well when treated at 58 ℃ even for 180 minutes. All the results implied that the fusion protein could be used as a potential immunodiagnostic agent in ELISA.

Changes of Sensory Properties and Antioxidant Activity of Citrus reticulata ‘chachi’Pulp during Fermentation
ZHOU Lin, HU Jin-mei, HONG Jun-feng, HUANG Zhi-feng
2020, 41(21): 116-121.   doi: 10.13386/j.issn1002-0306.2019120311
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To study the changes of sensory,chemical composition and antioxidant activity in the process of yeast fermented fruit juice of Xinhui Citrus reticulata'chachi’(CFJ),and promote rational utilization of the fruit pulp of Citrus reticulata'chachi’,the sensory properties were evaluated with six aspects of tissue state,color,sour taste,sweet taste,bitterness and aroma.The contents of total acid,reducing sugar,total phenols and total flavonoids were determined during fermentation. Meanwhile,the aroma components and relative contents were analyzed by gas chromatography-mass spectrometer.The antioxidant activity was evaluated with the clearance capacity of DPPH and OH free radicals. The results showed the fermented CFJ characterized with moderate taste,weak bitterness,fruity and fermented flavor was prepared under 0.5% inoculum of yeast A1 for 0~96 h culture at 40 ℃. The content of olefin in volatile aromatic substances was the highest,which increased from 53.70% to 77.77% after 0~96 h fermentation,and the main components were d-limonene and γ-terpene,followed by alcohols which decreased from 34.50% to 16.05%,esters from 7.74% to 2.44%,aldosterone and phenols(<1%). Furthermore,the contents of total acid and reducing sugar decreased gradually,while the content of total phenol and total flavone decreased significantly and then increased slightly. DPPH· scavenging rate decreased gradually during fermentation,which was significantly correlated with the contents of total phenols,total flavonoids,total acids and reducing sugar(P<0.05). The removal of ·OH decreased gradually and was significantly correlated with total acid content(P<0. 01),furtherly it was significantly correlated with total flavonoid content and reducing sugar content(P<0. 05). There was no significant correlation between ·OH clearance and total phenol content(P>0. 05).

Isolation,Identification and Flocculation Characteristics of a Pseudomonas Strain
LI Meng-xi, CAI Cheng-ru, GAN Guo-yuan, CAO Jing-xiao, JIANG Li-rong, ZHANG Zhen-wang
2020, 41(21): 122-127.   doi: 10.13386/j.issn1002-0306.2020010121
Abstract(4) PDF(1)
Abstract:

Objective:In order to obtain high efficiency and low cost microbial flocculant.Methods:Using conventional screening techniques to isolate and screen strains from the sewage sludge along the Longjiang River in Yizhou. The identification of the strains was carried out through morphological observation,physical and chemical analysis and molecular level 16S rDNA systematic evolution analysis;according to conventional methods,the flocculant was investigated in kaolin. The flocculation performance in activated carbon and yeast suspension and the factors affecting flocculation performance.Results:L2019-2 was identified as Pseudomonas veronii. The flocculant produced by L2019-2 had flocculant activity in both inorganic and organic suspensions.The flocculant’s flocculant activity was influenced by cation,pH,temperature and other factors. When the pH was 5.0,the temperature was 30 ℃ and the coagulant aid was Fe3+,the flocculant had the optimum flocculating activity in kaolin suspension. After chemical composition analysis,the flocculant was acid glycoprotein.Conclusion:The flocculant produced by L2019-2 has good flocculating activity,which can provide good strain resources for the study of microbial flocculant,and has better application potential in sewage treatment.

Analysis of Microbial Diversity of Rice Wine in Xuanen Area Based on MiSeq High-throughput Sequencing Technology
XIANG Fan-shu, LIU Xue-ting, DAI Cheng-yang, ZHANG Zhen-dong, GUO Zhuang
2020, 41(21): 128-132,138.   doi: 10.13386/j.issn1002-0306.2019110207
Abstract(4) PDF(1)
Abstract:

Three rice wine samples were collected from Xuanen county,Enshi Tujia and Miao Autonomous Prefecture,Hubei province and MiSeq high-throughput sequencing technology were established to investigate the biodiversity of bacteria and fungi of them. The result indicated that Pediococcus,Bacillus and Lactobacillus affiliated to Firmicutes,Pseudomonas,Acinetobacter and Enterobacter affiliated to Proteobacteria were domain generas,with the relative abundance of 74.10%,6.32%,3.03%,3.58%,1.22% and 1.08%,respectively. The result also indicated that Wickerhamomyces,Saccharomycopsis and Trichomonascus affiliated to Ascomycota,Amylomyces affiliated to Mucoromycotina were domain generas,with the relative abundance of 44.67%,23.10%,1.20% and 27.06%,respectively. The sequences cluster to core bacterial and fungal OTU were 89.88% and 98.80% of total sequences. Thus,rice wine samples collected from Xuanen county shared a large number of core bacterial and fungal microbiome.

Effects of Solid-state Fermentation of Lactobacillus paracasei on Active Components and Bacteriostasis of Jujube Meal
WEI Jia-wen, WANG Hai-kuan, ZHANG Hui-ling
2020, 41(21): 133-138.   doi: 10.13386/j.issn1002-0306.2020020225
Abstract(3) PDF(1)
Abstract:

Jujube meal and soybean meal were produced with solid-state fermentation by Lactobacillus paracasei. In order to explore the influence of the fermentation process on some functional substances and antibacterial properties in the substrate,the number of viable bacteria,γ-aminobutyric acid(GABA),different organic acids,crude polysaccharides,free amino acid and polyphenol content changes were analyzed. The results showed that the number of viable bacteria reached a maximum value of 6.5×108 CFU/g after 24 h of solid fermentation compared with before fermentation. At this time,the contents of GABA,lactic acid,crude polysaccharide and free amino acids in the matrix increased by 109.92 μg/g,23.14 mg/g,14.29 mg/g and 36.70 μg/g;the diameters of the zone of inhibition against Salmonella,Escherichia coli and Staphylococcus aureus were 3.12,2.79,1.24 cm,respectively. The ability of bacteria was obviously enhanced. Therefore,solid-state fermentation is beneficial to the development of intestinal probiotic products rich in live bacteria and various active components,and provides a new way for the development and utilization of red dates.

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Processing Technology
Optimization of Enzymatic Extraction Technology of Starch from Breadfruit by Response Surface Methodology
ZHONG Xue-yao, WANG Shao-man, ZHANG Yan-jun, XU Fei, TAN Le-he, YU Han-song, WU Gang
2020, 41(21): 139-144.   doi: 10.13386/j.issn1002-0306.2020010004
Abstract(9) PDF(10)
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In order to determine the optimum technological conditions of enzymatic extraction of breadfruit starch,neutral protease method was used to extract breadfruit starch. The effects of four factors,such as solid-liquid ratio,enzymatic hydrolysis temperature,enzymatic hydrolysis time and amount of enzyme,on the extraction rate of bread fruit starch were studied.On this basis,the response surface methodology was used to optimize the extraction technology of breadfruit starch. The results showed that the optimal combinations of extraction process for maximum breadfruit starch production were determined as solid-liquid ratio of 1:4 g/mL,enzymatic hydrolysis temperature of 62 ℃,enzymatic hydrolysis time of 6 h,and amount of enzyme of 0.13%,respectively. Under the best conditions,breadfruit starch extraction rate of the theoretical value was 69.66%,the actual value was 69.97%,the fitting model was in accordance with the actual verification. Neutral protease method is an efficient method for the extraction of breadfruit starch,which has the potential for industrial extraction of breadfruit starch.

Development and Evaluation of a Meal Replacement Powder with Low GI for Medical and Nutritional Weight Loss
LIU Yi-feng, XIONG Fei-fei, LI Ke-wen, JIA Fu-huai, DUAN Sheng-lin, HAN Xiao-feng
2020, 41(21): 145-150.   doi: 10.13386/j.issn1002-0306.2020020193
Abstract(10) PDF(3)
Abstract:

In order to develop a meal replacement powder suitable for obese people,a fat microcapsule was prepared by spray drying. Through the design of three energy-supplying nutrient ratios,a formula for meal replacement powder was obtained. The high-speed granulation process was used to improve the solubility of meal replacement powder. The glycemic index(GI)test was performed on meal replacement powder to evaluate the effect on blood sugar after consuming meal replacement powder. The results showed that the surface of the fat microcapsule particles was intact and dense. In addition,adding micro-capsules of composite antioxidant tea polyphenol palmitate(TP)and 0.15% of L-ascorbyl palmitate(L-AP)could further slow down the rise of oil peroxidation during storage and improve the oxidation stability of the oil. Secondly,after high-speed granulation,the fluidity of the meal replacement powder was significantly improved,and the fluidity index increased from 59.0 to 77.5. The particle size of the powder after granulation was mainly distributed around 600 μm,and it had a certain fast solubility,and the scattered light intensity of meal replacement powder after granulation was obviously higher than that before granulation. Finally,the GI value of the meal replacement powder was measured by human body,and the GI value was 52.2±5.1. After consumption,it can play a role in stabilizing blood sugar,which is suitable for people with abnormal glucose metabolism.

The Manufacture and Determination of the Texture Characteristics of a Newxinjiang Nuts Meringue Cut Cake
ZHANG Ting, ZHAO Dan, ZOU Shu-ping, PAN Yan, ZHANG Qian
2020, 41(21): 151-155,163.   doi: 10.13386/j.issn1002-0306.2020020055
Abstract(3) PDF(1)
Abstract:

In order to determine the optimum formula for a new Xinjiang nuts meringue cut cake,using the walnut and raisin as main raw material,assist to the low-gluten flour,high-gluten flour,potato flour,milk,water,corn oil and amendment etc,the single factor tests were utilized to investigate the effect of the proportion of walnut and raisin,the proportion of low-gluten flour,high-gluten flour and potato flour,the proportion of flour and pastry,and the amount of improver on the texture and sensory quality of Xinjiang nuts meringue cut cake,and the optimum formula of a new Xinjiang nuts meringue cut cake was obtained through L9(34)orthogonal tests. The result showed that the order of the effect of different factors on the sensory quality of Xinjiang nuts meringue cut cake was the proportion of flour and pastry>the proportion of walnut and raisin>the proportion of low-gluten flour,high-gluten flour and potato flour>the amount of improver. The optimum formula was the proportion of walnut and raisin 7:3,the proportion of low-gluten flour,high-gluten flour and potato flour 90:5:5,the proportion of flour and pastry 5:2,the amount of improver 1.2%.The sugar content of this new Xinjiang nuts meringue cut cake was only 13.80 g/100 g,and the maximum shear force was 1.86 N. Compared with the traditional Xinjiang nuts cut cakes,the sugar content was reduced by 23.76%,and the maximum shear force was reduced by 97.55%,it had low sugar content and was easy cutting,which could provide a new research idea and direction for the product development industrialization of Xinjiang nuts cut cakes.

Extraction,Purification and Stability of Purple Potato Anthocyanin
YU Shi-ying, WANG Wen-xiu, MA Qian-yun, MA Zi-ye, REN Cong-tao, GONG Ke-xin, SUN Jian-feng
2020, 41(21): 156-163.   doi: 10.13386/j.issn1002-0306.2020030003
Abstract(6) PDF(3)
Abstract:

In this paper,the ultrasonic assisted extraction of anthocyanin from purple potato was optimized by response surface methodology(RSM). The separation and purification of anthocyanin from purple potato and its stability under different environmental conditions were studied. The results showed that the optimum extraction conditions were as follows:Extraction power 300 W,ratio of material to liquid 1:50 g/mL,extraction temperature 50 ℃,extraction time 15 min,and extraction amount(1.435±0.27) mg/g.Using AB-8 resin,the amount of sample was 9 BV,eluted with 60% ethanol solution of 6 BV,the speed of sample loading and elution was 2.0 mL/min,and the concentration of purple potato anthocyanins in the purified extract reached(6.43±0.37) mg/mL. The results of stability study demonstrated that,the stability of anthocyanin of purple potato was poor under the condition of 245 nm short wave ultraviolet and indoor scattering light,and stable under the condition of avoiding light. The stability decreased with the increasing of temperature under the condition of heating,and was not stable at 90 ℃;it was stable in the solution containing Al3+,Mg2+,K,Ca2+,Na,Zn2+,and precipitated in the solution containing Cu2+. Purple potato anthocyanins were stable in an acid environment and easy to decompose in an alkaline environment. Therefore,anthocyanins of purple potato should be stored or used in the acid environment of dark,cold storage or normal temperature. The optimized extraction process of anthocyanin from purple potato was reasonable and feasible,and the extracted anthocyanin product had high stability,which could be used as a healthy food colorant or functional component in the food production and development process.

Extraction of β-Glucosidase from Abalone Viscera by Aqueous Two-phase System
ZENG Ying, ZHANG Ya-nan, ZENG Zhen, CHEN Zhong-wei, YU Li-li, WU Juan-ying
2020, 41(21): 164-171.   doi: 10.13386/j.issn1002-0306.2020010156
Abstract(5) PDF(1)
Abstract:

Extraction of β-glucosidase in the viscera of abalone by polyethylene glycol(PEG)/salt(NaH2PO4)aqueous two-phase extraction(ATPE)was studied. The molecular weight of PEG,PEG mass fraction,NaH2PO4 mass fraction,the effects of pH value,sample quantity and ultrasonic assisted method on the enzyme activity,purification factor and extraction rate of the lower phase were investigated and optimized by the single factor experiments and orthogonal experiments. The results showed that the composition of 12% PEG4000+15% NaH2PO4 at room temperature showed the optimal effect of extraction,with enrichment of target enzymes in the salt phase,and the enzyme activity was 1.45 U,extraction rate was 0.991,the distribution coefficient was up to 104,purified factor was 4.4. The optimum pH of the system was in natural state,as well as the maximum sample quantity was 20% of the total mass of the system. After the mixing of all components of the system,the ultrasonic treatment of 180 W for 5 min could slightly improve the extraction effect.

Optimization of Extraction Process of Volatile Flavor Extracts from Fish Sauce by Response Surface Methodology
CHEN Li-li, BAI Chun-qing, YUAN Mei-lan, JIANG Yong, ZHAO Li
2020, 41(21): 172-178,184.   doi: 10.13386/j.issn1002-0306.2019100117
Abstract(6) PDF(1)
Abstract:

HS-SPME-GC-GC-MS technology was used to study the volatile flavor substances in fish sauce. In order to optimize the extraction efficiency of flavor detection of HS-SPME in fish sauce,the number of peaks and peak volume,the response surface optimization experiment were used to determine the optimal conditions for the extraction of volatile flavors from fish sauce,and the best extraction conditions were as follows:extraction temperature 58 ℃,extraction time 70 min,oscillation frequency 510 r/min,under these conditions,the maximum number of peaks predicted by the model was 1558.55,and the peak volume was 7.56×1010. The volatile flavor substances were detected in the silverfish fish sauce samples under the optimal extraction conditions. A total of 152 compounds were detected and classified. The most abundant compounds were alcohols and esters,which were 26.02% and 25.91%,respectively. The established HS-SPME-GC×GC-MS method for the analysis of volatile flavor substances in fish sauce can better separate the components in samples with high resolution.

Ultrasonic Extraction and Antioxidant Activity of Polysaccharide from Dixu Tea
CHEN Hong-hui, NIUNIAN La-mu
2020, 41(21): 179-184.   doi: 10.13386/j.issn1002-0306.2020040275
Abstract(4) PDF(1)
Abstract:

In order to comprehensively utilize Dixu tea resources,ultrasonic assisted extraction technology and in vitro antioxidant activity of Dixu tea polysaccharide were studied. The effects of particle size,ultrasonic time,solid-liquid ratio,extraction temperature and ultrasonic power on the yield of polysaccharide were investigated. The optimal extraction process was determined by orthogonal test and its antioxidant activity was investigated.The results showed that the optimum extraction process was as follows:Particle size 40 mesh,liquid-material ratio 1:40 g/mL,ultrasonic time 110 min,ultrasonic temperature 60 ℃,ultrasonic power 750 W,under these conditions,the average extraction yield ofpolysaccharide was 11.28%±0.49%. The results of antioxidant activity in vitro indicated that the polysaccharide had a certain scavenging ability to the superoxide free radicals,hydroxyl radical,DPPH and ABTS free radicals,the rates were respectively 66.55%±2.67%,85.17%±1.70%,66.48%±2.99%,82.37%±1.00% at 2.0 mg/mL.The polysaccharide obtained under optimum extraction conditions exhibited strong antioxidant activities,which could be effectively used in making natural antioxidants.

Optimization of Ultrasonic-Microwave Assisted Extraction of Procyanidins from Hops Residue
WEI Wen-hui, LIU Xiao-bo, YU Chang-qing, ZHANG Xiao-xue, LI Bing, JIA Hong-zhen
2020, 41(21): 185-192.   doi: 10.13386/j.issn1002-0306.2019100109
Abstract(6) PDF(3)
Abstract:

In order to optimize the extraction process of procyanidins from hops residue,the hops residue extracted from hops extract by supercritical CO2 was used as the research object. Procyanidins were extracted by ultrasonic-microwave assisted ethanol extraction,and the content was determined by high performance liquid chromatography. Firstly,microwave power,microwave time,ethanol concentration,solid-liquid ratio,extraction temperature and extraction time were taken as single factors to study the effects of each factor on the extraction amount of procyanidins. On this basis,the extraction process was optimized by Plackett-Burman experimental design and Box-Behnken experimental design. The results showed that the optimal process for extracting procyanidins from hops residue by ultrasonic-microwave assisted was as follows:ultrasonic power 50 W,ultrasound-microwave treatment temperature 55 ℃,microwave power 540 W,microwave time 76 s,ethanol concentration 60%,extraction temperature 55 ℃,extraction time 1.0 h,material/liquid ratio 1:15 g/mL. Under this conditions,the extraction yield of procyanidins was 14.68 mg/g,at the same time,procyanidins were extracted by ultrasonic-microwave assisted was significantly higher than that of ultrasonic extraction and microwave extraction(P<0.05). This study can provide a theoretical reference for the comprehensive utilization of hop residue.

Optimization of Extrusion Technology and Physicochemical Properties of Ginseng Yam Blend
SONG Huan, ZHANG Rui, PANG Shi-feng, WANG Ying-ping
2020, 41(21): 193-198,207.   doi: 10.13386/j.issn1002-0306.2020020031
Abstract(2) PDF(1)
Abstract:

Expanded ginseng yam products were prepared by twin-screw extrusion process,and the best process and the changes of physical and chemical properties before and after extrusion were studied. Taking raw sun-dried ginseng and yam decoction pieces as experimental materials,the raw sun-dried ginseng powder and yam decoction piece powder were mixed according to the ratio of 1:1. The radial expansion rate of the expanded product was taken as the inspection index,the L9(34)orthogonal table was used on the basis of single factor to optimize process parameters of ginseng yam blend. And the nutritional quality,physical characteristics and effective components before and after expansion were compared and analyzed.The results showed that the optimum technological conditions were screw speed 250 r/min,Ⅲ area temperature 160 ℃ and moisture content 24%. Under these conditions,loose and porous expanded products could be obtained,and the radial expansion rate of the products reaches the maximum value of 2.43. Compared with the nutritional components before and after extrusion,there was no significant difference in crude ash content(P>0.05),but the crude fat,TDF,IDF,crude protein,soluble protein,total starch and amylopectin content all decreased(P<0.05). Soluble dietary fiber and amylose increased by 12.96% and 18.03% respectively(P<0.05). The gelatinization degree,WSI and WAI were improved after expansion compared with those before expansion of the physical properties. The correlation analysis of the basic nutritional and chemical components and physical properties of ginseng yam blend showed that the gelatinization change rate before and after expansion was significantly negative correlated with the change rate of starch content and amylopectin content(P<0.05),but the change rate of WAI value was significantly positive correlated with IDF(P<0.01),and the change rate of WSI value was significantly negative correlated with the change rate of amylopectin,fat,TDF and IDF content(P<0.05). Total ginsenosides decreased from 5.50% to 5.15% before and after expansion,with significant difference(P<0.05). Conclusion:Through the application of extrusion technology,the physical and chemical properties of ginseng and yam composite powder have been improved,which lays a theoretical foundation for further research.

Optimization of Enzymatic Hydrolysis on Vegetable Juice of Carrot,Tomato,Cucumber and Celery
ZHANG Cheng-hui, SHI Chao, FENG Xu-qiao
2020, 41(21): 199-207.   doi: 10.13386/j.issn1002-0306.2019100007
Abstract(7) PDF(1)
Abstract:

Objective:To optimize the technologiacal parameters of enzymolysis process on the vegetable juice of carrot,tomato,cucumber and celery juice. Methods:Pectinases and cellulases were added into the vegetable juice for enzymolysis during the juice extraction. Single factor experiments and orthogonal tests were conducted to optimize the enzymolysis conditions(enzymolysis time,enzyme addition,enzymolysis temperature)using juice yield and turbidity as the indexes. Results:The optimal enzymolysis conditions were as follows. For the treatment of carrot juice,enzymatic treatment time was 60 min with 0.4% pectinase at temperature of 40 ℃. Under these conditions,the obtained extraction rate and turbidity of carrot juice were 84.7% and 54.3 NTU. For the treatment of tomato juice,treatment time was 40 min with 0.2% pectinase at temperature of 40 ℃. Under the conditions,the obtained extraction rate and turbidity of tomato juice were 95.1% and 36.3 NTU. For the treatment of cucumber juice,reaction time was 60 min with 0.5% pectinase at temperature of 40 ℃. Under the conditions,the cucumber juice extraction rate and turbidity were 93.2% and 60.7 NTU. For the treatment of cucumber juice,reaction time was 60 min with 0.4% cellulase at temperature of 40 ℃. Under the conditions,the cucumber juice extraction rate and turbidity were 92.1% and 33.3 NTU. Conclusion:The vegetable juice with such optimal enzymolysis parameters were tasteful with attractive color with exploring value to be used as materials for production of fruit and vegetable or combined vegetable juice beverages.

Optimization of Extraction and Identification of Potassium Hydroxycitrate from Fruits of Garcinia cambogia L.
ZENG Yuan, SONG Ya-hui, YU Quan, HAN Yan-qi, JIN Chen-zhong, WANG Yan, ZHANG Xue-jiao, HU Yi-hong
2020, 41(21): 208-212.   doi: 10.13386/j.issn1002-0306.2020020011
Abstract(3) PDF(1)
Abstract:

In order to prepare the potassium hydroxycitrate from the fruits of Garcinia cambogia L.,the water extraction method was adopted to extract hydroxycitric acid from the powders prepared from G. cambogia L. fruits. The extractions were identified by the chromogenic reaction with ammonium monovanadate,thin layer chromatographic analysis and the HPLC analysis. The extraction process was optimized by the single factor test and the orthogonal test. The optimal conditions were as follows:The solid liquid ratio was 1:18,the condensive fold was 5,the alcohol degree was 60%vol,and the pH value was 12. The effects of various factors on the recovery rate of free hydroxycitric acid were in the order of solid liquid ratio>condensive fold>pH>alcohol degree. Under these optimal conditions,the recovery rate of potassium hydroxycitrate from the fruits of G. cambogia L. was 3.24%±0.32%. In the extraction process,KOH was used to protect the free hydroxycitric acid under the alkaline condition to form the potassium hydroxycitrate. A single peak whose retention time was the same to that of the hydroxycitric acid was detected by HPLC and its purity was 52.10%±0.53%. This method was better than the existing technology.

Optimization of the Production Process of L-Arabinose Tartary Buckwheat Tea Sucking Jelly and Its Hypoglycemic Effect
LI Qun-fei, LIU Hai-yan, WANG Lu-lu, ZONG Yu-xia, JIANG Jin-ju, MA Hai-yan, ZHUANG Xiao-wei, LIU Xiao-dong
2020, 41(21): 213-217,229.   doi: 10.13386/j.issn1002-0306.2019120038
Abstract(4) PDF(0)
Abstract:

In this paper,a sucking jelly with hypoglycemic effect was developed with sucking jelly powder A(seaweed dietary fiber powder)as the carrier,and Liangshan Tartary buckwheat tea and L-arabinose as the main functional raw materials. According to the sensory evaluation results,the effects of factors on the quality of L-arabinose Tartary buckwheat tea sucking jelly were determined by single factor and orthogonal experiments,the contributions for the quality were sucking jelly powder A(seaweed dietary fiber powder),Liangshan Tartary buckwheat paste,forming agent and L-arabinose in sequence. The results showed that the optimal formula of it was Liangshan Tartary buckwheat paste 12%,sucking jelly powder A(seaweed dietary fiber powder)0.3%,forming agent 0.14% and L-arabinose 8%. Based on this formula,the sensory score of product was 91.4±0.5 points. The sucking jelly has the characteristics of rich flavor,exquisite taste,feasibility of sucking and hypoglycemic effect,providing a reference for the development of new healthy sucking jelly products.

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Food Safety
Degradation of Fipronil and Its Metabolites during Processing of Yunnan Black Tea and Dietary Exposure Assessment
LIN Tao, PENG Li-yuan, CHEN Xing-lian, LIU Xing-yong, LI Mao-xuan, XU Yi-ran, ZOU Yan-hong, LIU Hong-cheng
2020, 41(21): 218-223.   doi: 10.13386/j.issn1002-0306.2020020021
Abstract(9) PDF(7)
Abstract:

The purpose of this study was to investigate the residual degradation of fipronil and its metabolites during the processing of black tea and its dietary exposure risk. In this study,ultra-high performance liquid chromatography-tandem mass spectrometry and TPT SPE columns were used to establish a high-sensitivity and rapid determination method for fipronil and its metabolites in black tea. In the negative ion MRM monitoring mode,the linear range of fipronil and its metabolites was 0.5~100 μg/mL,the linear relationship was good,and the minimum detection limit was 0.4 μg/kg. The average recovery rate under different additive concentrations was 84.4%~95.5%,which met the requirements of trace detection. By spraying fipronil and its metabolites in the fresh leaves of the black tea,and simulating the processing of the indigo tea,and sampling and measuring the content of fipronil and its metabolites in the main steps of the processing of the indigo tea,the results showed that the content of fipronil and its metabolites was continuously reduced during the processing of Yunnan black tea,and fipronil and its metabolites were largely degraded in the two steps of rolling and drying,and the degradation rates of these two steps ranged from 37.5% to 41.2% and 65.1% to 70.1%,respectively. The results of HQ calculation showed that the dietary exposure risk of fipronil and its metabolites was low,while the total hazard index HI was greater than 1,and the dietary risk was unacceptable. At present,fipronil and its metabolites have been banned in tea. It is less likely to use four pesticides in sapling tea,but should be taken seriously.

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Analysis and Determination
Establishment of an Enhanced Enzyme Inhibition Assay for Rapid Detection of Organophosphrous Pesticides Residues in Grain
WANG Wen-jun, YE Sheng-feng, XIE Yan-hong, YE Jin, LIU Xue-ying, WANG Song-xue, LI Jun, SANG Hua-chun
2020, 41(21): 224-229.   doi: 10.13386/j.issn1002-0306.2019110239
Abstract(5) PDF(5)
Abstract:

In this study,an enhancer-based enzyme inhibition method was established to achieve rapid detection of organophosphorus pesticide residues in cereals. The extractant,enzyme and enhancer used in the enzyme inhibition method were selected and optimized,by comparing the change of inhibition rate. Finally,butylcholinesterase was used as catalytic enzyme,ethanol selected as extractant,and bromosuccinimide as enhancer. Under these optimized conditions,the standard curves of parathion,phoxim,chlorpyrifos and triazophos were established(R2>0.98). The IC50 values were 0.01,0.11,0.16 and 0.03 μg/L,respectively,which met the safety residue limits of this kind of pesticides. 200 grain samples(rice,wheat,maize,brown rice,miscellaneous grains)were tested using the improved enzyme inhibition method,in which 13 positive samples were detected,however,due to the specific limitation of the enzyme inhibition method,1 false positive samples and 1 false negative samples were generated. Results of exemplarily performedgas chromatography were well in accordance with measurements obtained by enzyme inhibition,and it was proved that the developed method could be used to detect the organophosphorus pesticide residue in the grain. This study can provide a powerful technical support for China grain quality safety supervision.

Simultaneous Determination of Free Amino Acids in Wax Apple by Reversed Phase High Performance Liquid Chromatography with Phenyl Isothiocyanate Precolumn Derivatization
ZHANG Guo-hua, WU Guang-bin, CHEN Zhao-hua, ZHANG Shen, CHEN Fa-he
2020, 41(21): 230-234.   doi: 10.13386/j.issn1002-0306.2019120129
Abstract(5) PDF(2)
Abstract:

A high performance liquid chromatography method for simultaneous determination of 15 free amino acids in wax apple fruit by pre-column derivatization with phenyl isothiocyanate(PITC)was established. The separation was achieved using a Atlantis T3 column under the gradient elution with the mobile phases composed of 0.1 mol/L sodium acetate buffer(pH=6.5)and acetonitrile-water(4:1)at the flow rate of 1.0 mL/min,column temperature of 35 ℃ and UV detector wavelength at 254 nm.The calibration curves of amino acid component had good linearity over the range from 2.0 to 500 mg/L with correlation coefficient all above 0.99. The detection limits were in the range of 0.08~0.35 mg/L and the quantitation limit were in the range of 0.35~1.25 mg/L. The spiked recoveries were between 85.61% and 106.68% and the RSDs were less than 5%. This method could separate the 15 amino acids with high accuracy,high sensitivity and recovery. The method was successfully used to analyze the free amino acids in wax apple fruit.

Effect of Grape Seed Powder on the Flavor Components of Taigu Cake
ZHANG Qian-ru, YIN Rong, WANG Xian-ping, HAN Yan-long
2020, 41(21): 235-239.   doi: 10.13386/j.issn1002-0306.2019110035
Abstract(5) PDF(1)
Abstract:

Grape seed powder was added for researching the influence of the flavor components of Taigu cake by using gas chromatography-ion mobility spectroscopy and sensory evaluation. The methods showed that 18 kinds of flavor components were detected in the three types of Taigu cake,they were 6 kinds of aldehydes,3 kinds of ketones,5 kinds of alcohols,3 kinds of esters,and 1 kind of furans. The types of flavor substances in Taigu cake added with grape seed powder were not changed,but the content of various flavor substances changed,the relative content of ethyl acetate and 2-methylbutanol in Taigu cake increased from 1.67% and 0.65% in the control group to 8.62% and 7.25% in Taigu cake added with 10% grape seed powder,but 3-methylbutanal and hexanal decreased by 1.65% and 5.03%.Combined with the sensory evaluation results,the control group had the highest score,there was no significant difference between the three types of Taigu cake(P>0.05),the proportion of less than 10% could be accept by consumers. This study provides a scientific basis for the research of flavor components in Taigu cake and some ideas for the development and utilization of grape seeds.

Nutritional Evaluation and Volatile Flavor Compounds Analysis of Cultured and Wild Phascolosoma esculenta
CAI Bin-xin, ZHOU Feng-fang, HUANG Wei-qing, RUAN Shao-jiang
2020, 41(21): 240-245,252.   doi: 10.13386/j.issn1002-0306.2020020034
Abstract(5) PDF(0)
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The aims of this study were to analyze and evaluate the nutrient composition and volatile compounds of cultured and wild Phascolosoma esculenta. The results showed that crude protein content of cultured P.esculenta was significantly lower(P<0.05),while water and crude fat content were significantly higher than those of wild(P<0.05).The total amino acids content,essential amino acids content and flavor amino acids content of cultured P.esculenta were lower than those of wild.Flavor amino acids,arginine and lysine of cultured and wild P.esculenta accounted for 44.12%,10.23%,6.17% and 45.22%,9.85%,5.94% respectively. The unsaturated fatty acids(USFA)contents of cultured P.esculenta were lower than those of wild(P<0.05),accounting for 48.60% and 53.04% in the total fatty acids respectively,and C20:4 n-6 content was the highest. 40 volatile compounds was detected from cultured P.esculenta,including aldehydes,alcohols,ketones accounting for 30.10%,18.19%,13.47%.41 volatile compounds was detected from wild P.esculenta,including aldehydes,alcohols,ketones accounting for 31.53%,18.50%,19.59%.Both of cultured and wild P.esculenta showed fatty,mushroom earthy and grassy flavour. The substances which were mainly attributed to the flavour were octyl aldehyd,nonanal,(E)-oct-2-enal,(E)-non-2-enal,1-octen-3-ol,3-octenol and β-ionone. Based on these results,the nutritional quality,fishy smell and aroma characteristics of cultured P.esculenta were slightly lower than those of wild P.esculenta.

Fingerprint Analysis of Volatile Compounds in Stewed Chicken Broth
DU Chao, QI Jun, CAI Ying-xuan, ZHANG Hao, ZHANG Qing-yong, LIU Deng-yong
2020, 41(21): 246-252.   doi: 10.13386/j.issn1002-0306.2020020003
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Objective:in this paper,gas chromatography-ion mobility spectroscopy(GC-IMS)was used to analyze the concentration and type changes of volatile compounds in chicken broth with different stewing times. Method:168 chickens were stewed for 20 times. The chicken broth samples of the 1st,3rd,5th,7th,10th,15th and 20th strewing times were determined by GC-IMS. Results:After stewing for five times,the main flavor substances in the soup were aldehydes and alcohols,and the volatile compounds of aldehydes,ketones and alcohols increased slightly. With the increase of stewing times,the types of alcohols,hydrocarbons,nitrogen compounds and ketones increased greatly,and the contents of alcohols and ketones were higher. In general,after 15 times of stewing,the flavor substances remained stable. Conclusion:GC-IMS can be used for visual characterization of volatile compounds. This study have the theoretical guidance and practical application value for revealing the flavor formation of chicken broth.

Comparative Analysis of Active Ingredients,Antioxidant Activity and Aromatic Components of Three Kinds of Fermented Wine
WAN Jing-rui, JIANG Peng-fei, SHI Guan-ying, ZHANG Le, WANG Xiao-min, ZHAO Li-li, WANG Xu-zeng, WANG Zhao-gai
2020, 41(21): 253-260,265.   doi: 10.13386/j.issn1002-0306.2020040237
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Abstract:

Using Shaanxi production of persimmon,kiwifruit,pueraria as raw materials to brew functional fermented wine,the difference of physical and chemical indexes(alcohol content,soluble solid content,reducing sugar,total acid,pH),active ingredients(flavonoids,total phenols),antioxidant activity and aromatic components of three kinds of fermented wine were investigated by ultraviolet spectrophotometry,HS-SPME and GC-MS through the contrast experiments.The results showed that three kinds of fermented wine had their own characteristics,with significant differences being found in physical and chemical indexes,active ingredients and antioxidant activity. The alcohol content of three kinds of fermented wine was around 11%vol,and the soluble solids content was about 7.5%. The highest content of reducing sugar and total acid were persimmon wine(5.82 g/L)and kiwifruit wine(13.52 g/L)respectively. The content of flavonoids and total phenols in kiwifruit wine and pueraria wine were significantly higher than that in persimmon wine(P<0.05). Kiwifruit wine had the strongest ability of scavenging three kinds of free radicals,eliminating nitrite and total reduction capacity. Pueraria wine was right behind that of kiwifruit wine. But the ferrousiron chelating ability of three kinds of fermented wine was weak. A total of 7 kinds of 49 aromatic components were identified in three kinds of fermented wine. 33,37 and 38 kinds of aromatic components were found in wine of persimmon,kiwifruit and pueraria,with the key flavor compounds of 12,12 and 16,the modified flavor compounds of 7,12 and 6,the potential flavor compounds of 7,4 and 7,respectively. A total of 21 volatiles were identified in three kinds of fermented wine,and the higher content and ROAV value of components were alcohols and esters. Comprehensive analysis showed that fermented wine by different raw materials had significant differences in active ingredients,antioxidant activity and aromatic components,and the quality of kiwifruit wine and pueraria wine was better. This study provides theoretical basis for improving the quality of Shanxi fermented wine.

Quantitative Detection of Donkey Milk Adulteration by Real-time PCR Based on Single-copy Nuclear Genes
WANG Zhi-ying, LI Ting-ting, YU Wen-jie, QIAO Lu, CHEN Ai-liang
2020, 41(21): 261-265.   doi: 10.13386/j.issn1002-0306.2019120100
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In this study,a normalized TaqMan real-time polymerase chain reaction(PCR)approach was developed based on reference genes for quantitative detecting donkey milk adulterated with bovine milk in adulterated sterilized milk. With single-copy nuclear housekeeping genes replacing multicopy mitochondrial genes as reference and donkey-specific genes,an innovatively normalized assay based on a standard curve constructing by the Ct ratio(donkey genes/reference genes)vs. the donkey milk content was established with a good linear correlation(R2=0.9650)within the range of 5% to 100% of donkey milk. The quantification analysis of simulated adulterated milk samples containing 20%,50% and 80% of donkey milk revealed a high accuracy with an average recovery of 109.16% and an average CV value of 4.68%. Therefore,the method is rapid and accurate,which can determine whether donkey milk is adulterated and the proportion of adulteration.

Analysis on Appearance Trait and Nutrition Ingredient of Ginkgo Nuts in Tuole
YAN Dong, BU Cheng-hong, LIU Yun, KAN Huan, ZHAO Ping
2020, 41(21): 266-272.   doi: 10.13386/j.issn1002-0306.2020020026
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The appearance characteristics and main nutrients of nuts from five Ginkgo trees in Tuole Village in Panzhou City,Guizhou Province,China,were analyzed by the main component analysis. The results showed that the appearance characteristics of the nuts from five Ginkgo trees showed some differences,with variation between 3.960% and 19.992%,among which No. 4 was the one with the largest kernel weight. Ginkgo nuts were rich in nutrients,including protein(4.17%~5.47%),coarse fiber(1.10%~2.24%),total sugar(0.29%~0.73%),total acid(0.46%~0.55%),total flavonoids(0.014%~0.024%),vitamin C(22.7~36.0 mg/100 g),17 amino acids(32.19~52.44 g/100 g)and 9 mineral elements(480.17~620.27 mg/kg). Among the tested sample,the protein content in nuts of No. 4 was the highest(5.47%),whose total acids(0.54%)and total flavonoids(0.019%)were ranked as the 2nd,and the total sugars(0.62%)and amino acid(38.50 g/kg)contents were ranked as the 3rd. The main component analysis showed that the comprehensive scores of nut quality of the five Ginkgo trees(No. 1~No. 5)were -2.43,0.45,0.43,2.17 and -0.07,respectively,indicating the best comprehensive quality for Ginkgo tree No. 4.

Taste and Flavor Characteristics of Peony Flower Tea under Different Soaking Methods
YUAN Qin-qin, LIU Wen-ying
2020, 41(21): 273-280.   doi: 10.13386/j.issn1002-0306.2020020195
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In order to acquisition the taste and flavor characteristics of peony flower tea under different soaking methods,the sensory characteristics were analyzed. Four kinds of tea liquor were prepared by soaking in the hot water for 30 s,in the cold water soaking for 30 min,1 h and 2 h. The main flavor characteristics and similarity of tea were analyzed by electronic nose,the taste characteristics of tea were quantified by electronic tongue,and the volatile organic compounds of tea were quantified by thermal desorption and gas chromatography mass spectrometer. Results showed that the main flavor characteristics of tea liquor soaked in hot water was similar to that of tea soup soaked in cold water for 1 h. Tea liquor soaked in cold water for 30 min and 2 h could be effectively distinguished from tea soup soaked in hot water and tea soup soaked in cold water for 1 h. There was no significant difference in taste characteristics between different preparation methods,except the sour,astringent and bitter aftertaste. There were more alcohols and esters in the tea soup. With the extension of soaking time,the contents of esters and alcohols in the cold water tea soup gradually decreased,while the contents of alkane gradually increased. Combined with the main flavor and taste characteristics,with the use of cold water soaking for 1 h instead of hot water,the peony tea had a similar flavor,while the sour,astringent and bitter aftertaste improved.

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Storage and Preservation
Effect of Plasma Activated Water on Microbial Decontamination and Storage Quality of Fresh-cut Lettuce
YUAN Yuan, HUANG Ming-ming, WEI Qiao-yun, ZHANG Jian-hao, YAN Wen-jing
2020, 41(21): 281-285,292.   doi: 10.13386/j.issn1002-0306.2019120106
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Objective:The microbial inactivation and quality changes of fresh cut lettuce treated with cold plasma activated water were investigated in this paper. Methods:PAW was produced by dielectric barrier discharge at 35,55 and 75 kV for 5 min. All samples were washed with PAW for 5 min and stored for 10 days(4 ℃,85% RH). The microbe(total aerobic plate count and coliform group),as well as the weight loss rate,color,ascorbic acid,chlorophyll and polyphenol oxidase activity of the samples were tested every two days. Results:The sterilization effect of PAW on lettuce significantly increased with the increase of treatment voltage(P<0.05).At the end of storage,the total colony count and coliform count of the 75 kV treatment group were 1.15 lg(CFU/g)and 1.38 lg(MPN/100 g)lower than the control group,respectively. Meanwhile,PAW treatment could effectively decrease the PPO enzyme activity and color change of samples(P<0.05),but there was no significant difference between different treatment groups(P>0.05).The 35 and 55 kV treatments had no significant effect on the ascorbic acid and chlorophyll content of the samples,but when the voltage increased to 75 kV,it would have an adverse effect. Conclusion:The optimum treatment voltage of PAW for keeping fresh of fresh cut lettuce was 55 kV.

Effect of 1-MCP Treatment on Postharvest Quality of Malus asiatica Stored at Room Temperature
ZHANG Long, JIANG Hao, LI Li-juan, MU Qian, ZHANG Quan-quan, ZHANG Wang-xiang
2020, 41(21): 286-292.   doi: 10.13386/j.issn1002-0306.2019120340
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In order to investigate the effect of 1-MCP treatment on the storage quality of Malus asiatica with room temperature,taking Malus asiatica with different maturity as experimental materials,the effects of 1-MCP(1.0 μL/L)fumigation treatment on the quality of the fruits during storage(20±1 ℃)were studied. The results showed that,compared with the control group,1-MCP treatment could effectively improve the color of two mature fruits,slow down the increase of decay rate and weight loss rate,maintain the fruit firmness(5.68~9.18 kg·cm-2),reduce the respiration intensity and postpone(10~15 d)the appearance of peak respiration intensity,and delay the decline of the titratable acid content(TA),vitamin C content(VC)and soluble solids content(SSC). Among the two maturity grades of Malus asiaticas,the low maturity fruits had the best storage effects,lower decay rate and weight loss rate,delicious sweet and sour taste,and bright color of red and green.

Antibacterial Activity of Atmospheric Cold Plasma Treatment Against E. coli O157:H7 Biofilms on Fruits and Vegetables
LIN Lin, CHEN Wen-qing, FANG Hou-zhi, GAO Jie, CUI Hai-ying
2020, 41(21): 293-298.   doi: 10.13386/j.issn1002-0306.2019100076
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The experiment explored the optimal power and time of ACP treatment on E. coli O157:H7 biofilms and its antibacterial mechanism. The morphological changes of biofilm before and after ACP treatment were also observed by field emission scanning electron microscope. Finally,ACP treatment was applied to the clearance of E. coli O157:H7 biofilms on the surface of four fruits and vegetables. The experimental results showed that ACP inhibited the formation of biofilms by inhibiting the synthesis and secretion of polysaccharides and proteins in the extracellular polymer at the optimal treatment power of 400 W and the optimal treatment time of 3 min. On the day of processing,98.99%±0.38%,99.92%±0.20%,96.84%±0.18%,99.80%±0.23% of the E. coli O157:H7 biofilms on the surface of the four fruits and vegetables,including Hutai grape,cherry tomato,Victoria green grape and lettuce,were respectively cleared,and exhibited good inhibitory effects within 5 days,extending the storage period of the four fruits and vegetables. Combined with the results of color and sensory evaluation,ACP treatment could remove E. coli O157:H7 biofilm on the surface of fruits and vegetables without affecting the sensory quality of the four fruits and vegetables.

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Nutrition and Healthcare
Study on Degradation and Intestinal Absorption of Poria cocos Polysaccharides in Artificial Gastric Juice and Intestinal Juice
CAO Nan, ZHAO Zhen, ZHAO Yu-tong, JIANG Tian-yang, CHU Jing, ZHANG Yue, CHEN Wei-dong, YU Nian-jun
2020, 41(21): 299-303.   doi: 10.13386/j.issn1002-0306.2019100063
Abstract(9) PDF(3)
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Taking Poria cocos polysaccharide as the research object,the digestion and absorption process of Poria cocos polysaccharide in rats was studied by simulating human gastrointestinal environment in vitro and intestinal perfusion in vivo. In this experiment,the degradation of Poria cocos polysaccharide in artificial gastric juice was detected,then the degradation of gastric degradation fluid in artificial intestinal juice was detected,and finally the absorption of polysaccharide in body intestine was explored. The results showed that Poria cocos polysaccharide was degraded rapidly and completely in artificial gastric juice within 0.5 h,forming many fragments stable in gastric juice,and almost no degradation in intestinal juice. Poria cocos polysaccharide were mainly absorbed in the intestine,and the higher the initial concentration of polysaccharide,the higher the absorption percentage(ρ). In the process of absorption,the absorption rate constant(Ka)of different initial concentrations of polysaccharides increased at first and then decreased. When absorbed to 120 min,the absorption percentage of the gastrointestinal degradation solution with initial polysaccharide concentration of 0.1004,0.5007 and 1.0004 mg/mL reached(23.52%±0.57%),(49.14%±0.87%)and(57.56%±0.22%),respectively. The study showed that Poria cocos polysaccharide were mainly degraded in gastric juice and absorbed in body intestine in mice.

Regulatory Effect of Dendrobium officinale Kinura et Migo Glycoprotein on Skin Inflammation and Its Mechanism
ZHAO Qian, DAI Tian-yi, HONG Wen-long, ZHOU Li-mian, SU Hai-ran, TIAN Yang, BAI Zhong-bin
2020, 41(21): 304-310,316.   doi: 10.13386/j.issn1002-0306.2019120094
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The aim of this study was to investigate the regulation and mechanism of Dendrobium officinale Kinura et Migo glycoprotein(DOKMG)on skin inflammation.In this paper,macrophage cell line RAW264.7 was targeted and stimulated by DOKMG in different time and concentration,the mRNA expression levels of inflammatory factor IL-1β,IL-6,TNF-α and inflammation-related COX-2 and iNOS were detected by RT-PCR. The expression of inflammatory factors in supernatant of macrophages was detected by ELISA. Western blot was used to analyze the effect of DOKMG on the expression of inflammatory factor protein and NF-κB signaling pathway. The results showed that DOKMG significantly promoted the expression of IL-1β,IL-6,TNF-α genes after 24 h(P<0.001).When the concentration reached 100 μg/mL,the improvement was the most obvious. Compared with the control group,IL-1β increased by 10.09 times,IL-6 increased by 20.45 times,and TNF-α increased by 0.95 times. When the concentration was 100 μg/mL,the secretion of TNF-α、IL-1β increased from 0.52 μg/mL and 118.52 pg/mL to 1.99 μg/mL and 272.81 pg/mL,the expression of inflammatory cytokines and phosphorylation of NF-κB were significantly promoted(P<0.05).These results indicate that DOKM can significantly promote macrophage inflammatory response to promote wound healing,and its mechanism may be related to the activation of NF-κB signaling pathway.

Activation of Macrophage of Phenylethanol Glycosides Extracted from Cistanche tubulosa and Its Synergistic Effect with Angelica sinensis and Astragalus propinquus in Regulating Immunity
LUO Zi-yan, QING De-gang, SUN Yu, XU Xiao-qin, ZHANG Juan, WANG Zi-rong
2020, 41(21): 311-316.   doi: 10.13386/j.issn1002-0306.2019110203
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Object:To study the activation effect of phenylethanol glycosides extracted from Cistanche tubulosa on macrophages,and to screen for a prescription,to investigate its immune-enhancing effect on normal mice. Methods:Studied on the role of phenylethanol glycosides on macrophage RAW264.7 activation and TNF-α,IL-6 production by the macrophage activation experiments.Compared the effects of angelica and astragalus on the activation of macrophages of phenylethanol glycoside extract.To evaluate the immune-enhancing function of tablets,which were prepared based on the screening test,by the ConA induced mice spleen lymphocyte transformation test,delayed-type hypersensitivity test,antibody-forming cell test,mice carbon clearance test and macrophage devour chicken erythrocyte test. Results:The results showed that 75,100,125 g/L groups could improve the activity of RAW264.7 cells,improve the level of NO,iNOS,TNF-α and IL-6,and 100 g/L group had the best effects(P<0.01). And the adding of angelica and astragalus can improve the activation function of phenylethanol glycoside on macrophages. The animal experiment of tables showed that 0.4 and 1.2 g/kg·bw/d groups could promote lymphocyte proliferation(P<0.05),1.2 g/kg·bw/d group could promote cellular immune response(P<0.05),0.4 g/kg·bw/d group could promote antibody production(P<0.05),1.2 g/kg·bw/d group could improve the ability of carbon clearance and macrophage phagocytosis(P<0.05). Conclusion:Phenylethanol glycosides extracted from Cistanche tubulosa may be to stimulate NO synthesis through induce iNOS expression,and to stimulate TNF-α and IL-6 releases,thus activate the immunomodulation of macrophage.The compound tablet prepared with phenylethanol glycosides angelica and astragalus can enhance the immunity of normal mice by regulating cellular immunity and monocyte-macrophage function,and exert positive effects on humoral immunity.

Hypoglycemic Activity and Renal Protection Effect of Seabuckthorn Seed Protein Peptide in db/db Mice
SHU Dan-yang, XIONG Jian, LIU Peng-zhan, CUI Chun
2020, 41(21): 317-321.   doi: 10.13386/j.issn1002-0306.2020010264
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The hypoglycemic activity of seabuckthorn seed protein peptide in type 2 diabetic mice and the protection effect on kidney were studied. Taking m/m mice as the normal control group(NC)and db/db diabetic mice as the research objects,the positive control group(PC)was administrated gavaged with 300 mg/kg/d metformin,and seabuckthorn seed protein peptide(SSPE)was divided into low,medium and high dose groups(50,150,250 mg/kg/d)for 8 weeks. The body weight,blood glucose,organ index,kidney related indexes and renal histopathological sections were measured to evaluate the hypoglycemic activity and renal protective effect of SSPE. db/db was a kind of diabetic mice with gene deficiency. At the early stage of treatment,the mice in the blank control group(BC)showed symptoms of hyperglycemia,obesity,more drinking,eating and urinating.4 weeks later,the mice in the BC showed more serious symptoms of "three more and less" than those in the SSPE group. After 8 weeks of intervention,the blood glucose value of SSPE group(low,medium and high:19.53,19.94,20.00 mmol/L)were significantly lower than that of BC group(29.56 mmol/L). The organ index and kidney related serum indexes of SSPE group were significantly lower than those of BC group(P<0.05),and the typical symptoms of diabetic nephropathy were also improved. The results showed that SSPE can significantly reduce the blood glucose level of diabetic mice,and exert protective effect on renal function.

Study on Immune Regulation of Perilla frutescens Seed Protein in Mice with Low Immunity
ZHU Yan, JIANG Sheng, LI Ming-liang, DONG Zhe, WANG Yu-qing, GUO Ying, GU Rui-zeng
2020, 41(21): 322-326,332.   doi: 10.13386/j.issn1002-0306.2020020189
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Objective:To study the effect of Perilla frutescens seed protein on immune system regulation in immunocompromised mice. Methods:Cyclophosphamide(CTX)was injected intraperitoneally to establish a model of immunocompromised mice. The effects of low,medium and high doses of Perilla frutescens seed protein on visceral index,T/B lymphocyte proliferation,serum hemolysin,NK cell killing,phagocytosis index,serum IL-2 and IgG levels in mice were detected. Results:With the increasing of concentration of Perilla frutescens seed protein,the immunomodulatory effect of Perilla frutescens seed protein first increased and then decreased Medium dose of Perilla protein increased T/B lymphocyte proliferation,hemolytic value(HC50),NK cell lethality,macrophage phagocytosis,and serum cytokine IL-2 and IgG levels in immunocompromised mice,and there were significant differences compared with the model group(P<0.01). Conclusion:Perilla frutescens seed protein play a good role in immune regulation in immunocompromised mice.

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Reviews
Research Progress on Preservation Technology of Fresh-cut Cauliflower
WANG Jia-yu, HU Wen-zhong, GUAN Yu-ge, YU Jiao-xue, ZHAO Man-ru
2020, 41(21): 327-332.   doi: 10.13386/j.issn1002-0306.2020020028
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Cauliflower is a nutritional and anti-cancer functional vegetable due to its antioxidant substances such as flavonoids and glucosinolates. Fresh-cut cauliflower is very popular with consumers because of its convenience,rapidity and freshness,however,fresh-cut cauliflower is prone to browning and microbial infection in the process of storage and sales due to mechanical damage,resulting in deterioration of quality and shortened shelf life. Therefore,understanding how to effectively maintain the quality of fresh-cut cauliflower and extend its shelf life is the key of fresh-cut cauliflower processing technology. This paper systematically introduced techniques that have been used for preserving fresh-cut cauliflower,including physical(ozonewater,packaging,UV-C,microwave,light,heat,etc.),chemical(calcium lactate,ascorbic acid,cetylpyridinium chloride)and biological preservation technology(microbial antagonism,natural extracts,genetic engineering),which provides the oretical reference for future research on fresh-cut cauliflower preservation.

Research Advances on Umami Substances in Food
HUAN Si-qi, LIU Deng-yong, WANG Xiao-dan, ZHANG Qing-yong
2020, 41(21): 333-339.   doi: 10.13386/j.issn1002-0306.2020020157
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As one of five basic tastes,umami plays an important role in the taste and people’s evaluation of food. This article takes umami as the central,some foods which are rich in umami introduced and several newer extraction methods of umami from macro perspective are summartzed. In addition,this article also summarizes some amino acids,nucleotides,peptides,organic acids and bases which are rich in umami from micro perspective. Two basic umami receptor proteins umami perception and umami synergy are briefly described,and the umami taste mechanism is analyzed from two aspects. The commonly measurement and analysis methods of umami are summarized(sensory evaluation,high performance liquid chromatography,capillary electrophoresis,and relatively new biological and chemical sensor methods). It is expected to provide a theoretical reference for the further study on the excavation,esthesia and detection of umami substances in food.

Research Progress on Characteristics and Preparation of Kokumi Peptides
HUANG Yu-ran, YANG Juan, WANG Wei, BAI Wei-dong, ZENG Xiao-fang, HUANG Wen-biao, CHEN Jie
2020, 41(21): 339-344.   doi: 10.13386/j.issn1002-0306.2020030207
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Due to the taste characteristics of food are very complex and cannot be described by a single basic taste,it is customary to use "kokumi" to describe a comprehensive taste such as thickness,richness,consistency,harmony and fullness in food. Kokumi peptides were widely found in animals,plants,and fermented foods. They have no taste,or have only a light taste,but the addition of small amounts of kokumi peptide can enhance the basic taste of the compound solution or broth,and give it a sense of thickness,consistency and coordination. In this article,the research progress on the origin,structural characteristics,taste characteristics,taste mechanism and preparation methods of kokumi peptides are reviewed. This paper provides the basis and reference for in-depth research of kokumi peptides and development of new condiments.

Mechanism of Nano-embedding Technology of Plant Essential Oil and Its Application in Meat Preservation
TANG Min-min, WANG Hong-yi, LIU Fang, ZHU Yong-zhi, WANG Dao-ying, XU Wei-min, SUN Zhi-lan
2020, 41(21): 345-350.   doi: 10.13386/j.issn1002-0306.2020020013
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Meat is easy to be oxidized and putrescent during transportation,storage and sales due to its rich nutrients and high-water activity. Therefore,meat preservation has become a major challenge in the food industry. Plant essential oil,a natural food preservative,has the potential to be used in the field of meat preservation based on good antibacterial and antioxidant effects. However,its application in the field of meat preservation is limited because of its poor water solubility and stability. This paper summarized the antibacterial and antioxidant capacity of plant essential oil with problems in application of meat preservatives,the method of nano-embedding of plant essential oil and its functional mechanisms on foodborne microorganisms. The paper prospected the development and application of nano-embedding technology of plant essential oil,in order to provide a reference for exploring new meat preservatives.

Research Progress on Polyphenol Activity and Separation and Purification of Walnut Fruit
ZHENG Xiao-ning, LI Jun, MU Jian-lou, CHEN Yong-hao, HAO Yan-bin, QI Jian-xun, DONG Ning-guang, ZHANG Yun-qi
2020, 41(21): 351-358.   doi: 10.13386/j.issn1002-0306.2019120310
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Walnut(Juglans regia L.)polyphenols mainly include phenolic acids and tannins,as well as small amounts of flavonoids,which are important chemical components of walnut fruit. Polyphenols are discarded along with processing by-products in walnut production,resulting in resource waste. The phenols of walnut exhibit many bioactivities and varieties and their contents in different parts of the walnut fruit have large differences. The types,contents,biological activities,separation and purification of phenolic compounds in walnut fruits are summarized in this paper,which provides a theoretical basis for in industrialization of phenols.

Research Progress on the Bioactive Substances of Sunflower Seeds and the Flavor Compounds after Cooking
HU Hang-wei, LIN Xiang-na, TANG Xiao-juan, LIN Xiang-sheng, WANG Liang, LIU Yun-guo
2020, 41(21): 359-364.   doi: 10.13386/j.issn1002-0306.2020020032
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As one of the important oil crops in China,sunflower seeds are rich in chlorogenic acid,linoleic acid,sterol and other bioactive substances. Studies have shown that sunflower seeds have the beneficial effects of anti-oxidation and immunity enhancement,as well as many other properties. Fine extraction not only makes it possible to extend the range of application,but also improves bioavailability. After cooking,sunflower seeds can increase appetite by the unique flavor,and its component plays an important role in the formation of flavor substances. The characteristic flavors are produced by carbonyls and pyrazine compounds,which have been widely recognized scholars in the industry. This paper reviewes the bioactive substances of sunflower seeds and the research status of extraction technologies,the flavor compounds after cooking and key flavor substances,which provides reference for the efficient and comprehensive utilization of sunflower seed resources,even achieves the good prospects of sunflower seeds industry.

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