Analysis of antioxidant activity of pectin and hemicellulose extracted from tomato fruit

Water-soluble pectin(WSP),chelate-soluble pectin(CSP),sodium carbonate-soluble pectin(SSP),loose-bonding hemicellulose(LH)and tight-bonding hemicellulose(TH)were extracted from tomato fruit cell wall with water,EDTA,Na₂CO₃,4% and 24% KOH. The antioxidant activity of different pectins and hemicellulose were studied,including oxygen radical absorbance capacity(ORAC),DPPH radical(DPPH·)scavenging capacity,ABTS radical(ABTS⁺·)scavenging capacity and ferric reducing antioxidant power(FRAP). It was suggested that the content of WSP(1.05 mg GalUA/g FW)was significantly higher than CSP and SSP in tomato fruit,and the content of TH(0.09 mg Glu/g FW)was significantly higher than LH(p<0.05). And different pectins and hemicellulose from tomato fruit all showed antioxidant activity in different degree,CSP's total antioxidant activity was higher than other cell wall components with higher ORAC,DPPH· scavenging capacity and ABTS⁺· scavenging capacity,when the concentration was 5 mg/mL,its ORAC value was 76.4 μmol/L Trolox equivalent,and the DPPH· scavenging rate and ABTS⁺· scavenging rate was 61.0% and 99.8%,respectively. But SSP,LH and TH possessed higher FRAP. Correlation analysis suggested each cell wall component was closely related with antioxidant activity. This result made a reference to comprehensive utilization of tomato fruit and the application of functional additive in food.