The Prevention of Oxidized Flavor in Milk and Ice Cream by the Use of Concentrated Milk Products

Certain constituents of milk have been shown to be antioxidants.Kende (10) pointed out in 1934 that the ascorbic acid in milk was part of the reducing system that protected against oxidation ; however, he believed that ascorbic acid was only a part of a complex reducing system.Gould (7) reported that substances other than ascorbic acid constituted from 40 to 60 per cent of the reducing system.Corbett and Traey (2. 3) have observed that certain amino acids, particularly tyrosine and its ethyl ester, may be natural antioxidants.Barnicoat and Palmer (1) reported that the soluble phosphates and citrates appeared to account for much of the antioxigenic effect of milk plasma.Gould and Sommer (8) and Josephson and Doan (9) have shown that a reducing system produced when milk is heated to high temperatures is effective in retarding oxidized flavor.The process of milk condensing was demonstrated by Corbett and Tracy (2) to retard the oxidized flavor.Dry milk may also be an antioxidant.As early as 1931, Dahle et al. (6) found that ice cream containing dry skimmilk did not develop "a peculiar cardboard or tallowy flavor" noticed in the control samples.When Dahle and Folkers (5) found less copper in ice cream made with dry milk, they reasoned that this accounted for its superior storage qualities.However, Dahle (4) pointed out later that the copper content was not the only factor involved, but that dry milk itself may have antioxygenic properties.Incidental to some experiments on homogenization, Trout and Gould (14) observed that when dry skimmilk was added to milk, oxidized flavor decreased in intensity or was prevented entirely, partially due perhaps to the flavor imparted by the higher concentrations of the dry skimmilk powder.Musher (11) was granted a patent in 1940 on the addition of concentrated or dried milk-solids-not-fat to cream followed by a heat treatment to stabilize the flavor of the cream and products made from it.Corbett and Tracy (3) observed that a slight antioxidant effect was given by skimmi]k powder.