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Vitamin B₁₂ in Wheys Prepared by Coagulating Milk with Acid and Rennet¹

Department of Food Science and Technology, University of California, Davis

ABSTRACT

The U.S.P. microbiological assay procedure for vitamin B₁₂ activity was followed, using Lactobacillus leichmanii ATCC 7830. Three samples of pasteurized milk and 16 samples of pasteurized skimmilk averaged, respectively, 4.0 and 4.7 of vitamin B₁₂ per liter. Comparison of amounts of vitamin B₁₂ in wheys and original milks indicated that both casein and whey proteins bind the vitamin. Rennet extract caused hydrolysis and/or separation from casein of some of the bound vitamin B₁₂. Six rennet wheys contained an average of 60% of the vitamin B₁₂ present in the original milk or skimmilk. Six acid wheys contained an average of 44% of the vitamin present in the original skimmilk. The separation of bound vitamin B₁₂ from casein was influenced by rennet concentration and time at 40° C.

¹ These data were taken in part from a thesis presented by the junior author in partial fulfillment of the requirements for the degree of Master of Science, University of California.