Evaluation of selected enzymes for thiamine determination.

Seven commercially available enzymes were studied for suitability as substitutes in the AOAC thiamine determination, because the enzyme Takadiastase used in the method has not been available since 1976, and alternative enzymes were likewise unavailable or unsuitable for releasing thiamine from its phosphate esters. Four factors (substrate ester, enzyme level, time/temperature, and pH) at 2 levels were studied in a 2(4) factorial arrangement of treatments. Data were expressed in terms of mean percentage conversion (MPC) and were statistically evaluated by analysis of variance. Significant main effects and any interactions among treatments were calculated. Takadiastase and alpha-amylase (Miles) with MPCs of 101 and 102, respectively, appeared effective in dephosphorylation within method parameters. Potato phosphatase appeared marginally suitable. Wheat germ phosphatase, alpha-amylase (Sigma), Mylase 100, and Clarase 40,000 were judged unacceptable as enzyme substitutes.