[Effect of pretreatment on the measurement of folate in foods].

In order to measure the content of folate in foods accurately, to hydrolyze and extract folate in foods with suitable pretreatment is necessary because folate in foods is always in polyglutamate structure. The pretreatment of samples including hydrolysis with phosphate buffer(0.05 mol/L, pH 6.8) once or twice, with chick pancreatin, protease and/or amylase, and a combining of trienzyme methods was compared and discussed. A microbiological method with lactobacillus casei was used. A high result of folate in foods could be obtained when extracting folate enriched samples or vegetables with phosphate buffer once or twice respectively, or hydrolyzing "extracted oral liquids" with chick pancreatin, or when extracting samples rich in protein and/or starch with trienzyme. The RSD of interassay and intrassay were 6.5%-9.9% and 3.5%-14.1% respectively, and the recovery rate was 86.8%-106.8%.