Rapid Determination of Folic Acid Content Range in Food by Microbiological Method

A method for rapid determination of folic acid content range in food by Lactobacillus casei ATCC 7469 was proposed in this paper. Since folic acid was the specific demand for the growth of Lactobacillus casei,the whole culture system was reduced from 10 mL to 1 mL in disposable centrifuge tubes instead of glass tubes and the incubation time was shortened from about 24 h to 8~12 h. After simple conversion of the absorbance data,the range of folic acid content of the sample was obtained,and the methodological investigation was carried out. The feasibility of the method was compared with the national standard method (GB 5009.211-2014). The results showed that,under the laboratory conditions,the detection limit of this method was 0.4~0.8 μg/100 g,the linear range 0.01~0.08 ng,and the recovery rate 82.1%~108%. The detection limit range of this method could be used to estimate the lower limit range of folic acid content,and the linear range could be used to estimate the upper limit range of folic acid content. Compared with the national standard method,which took 2~3 d for the determination,this method only need 1 d,which had simpler steps,and could savereagent materials.