The Reducing Capacity of Milk and Milk Products as Measured by a Modified Ferricyanide Method

Abstract

A modification of Chapman and McFarlane''s ferricyanide procedure for evaluating the reducing capacity of milk is presented. This modification, involving raising the pH to 6.6 and lowering the temp. to 50 C, proved somewhat more satisfactory, particularly with milk powders of high reducing ca- pacity, than the original method. The method has been calibrated in terms both of ferricyanide reduced and of cysteine or ascorbic acid oxidized. The capacity of milk to reduce ferricyanide is increased both by heat treatment and by spray drying: Study of simplified systems of milk constituents has shown that some of the reducing substances produced by heat treatment of milk and aging of dry milk are formed from lactose and from prptein-lactose interactions.