Radiometric Determination and Chick Bioassay of Folacin in Fortified and Unfortified Frozen Foods

A radiometric assay for food folacin based on the competitive protein binding procedure was developed. The method is rapid, reliable and comparable to the microbiological assay. Cooking and storage did not significantly affect the folacin content of frozen fortified or unfortified frozen dinners and pies. Food folacin availability was measured by chick bioassay. The procedure involves feeding semi‐purified diets containing various levels of folic acid and/or cooked or uncooked frozen convenience foods and measuring plasma and RBC folacin. Levels were directly related to folic acid intake from semipurified diets. Availability of folacin acid added to TV dinners and pies was demonstrated by elevation of plasma and RBC folacin, but fortification of vegetables did not cause consistent elevation.