Comparison of Conjugase Treatment Procedures in the Microbiological Assay for Food Folacin

Variations in the conjugase treatment step of the microbiological assay for food folacin were investigated. The source of the conjugase–fresh hog kidney, fresh chicken pancreas or commercial dried chicken pancreas–did not significantly affect the measurable folacin activity of spinach. However, the buffer, pH, incubation time, sequence of steps in extraction and conjugase treatment, and method of sample filtration (filter paper vs centrifuge) used prior to conjugase treatment were all found to significantly affect the folacin activity of spinach.