The Relationship of Ascorbic Acid to the Development of Oxidized Flavor in Market Milk

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Abstract
Addition of ascorbic acid to pasteurized milk at the rate of 1.5 g. per 100 lb. of milk inhibited the development of oxidized flavor for a period of 5-7 days. Control samples developed an oxidized flavor after 2-3 days'' storage. Non-fortified milk lost more than 1/5 of its ascorbic acid during the 1st day of refrigerated storage in the dark, about 1/2 by the 2d day, 3/4 by the 3d day, and more than 90% by the 5th day. Milk fortified with ascorbic acid lost less than 1/10 during the 1st day, slightly more than 1/5 the 2d day, about 1/3 by the 3d day, and about 1/2 after 5 days'' storage. Fortified milk lost its ascorbic acid rapidly when exposed to light, the rate depending upon the intensity of light and the time exposed. When exposed to direct sunlight for 40 min., all measurable ascorbic acid was destroyed. The destruction of ascorbic acid was only slight when milk was carried in standard wood cases, in a covered milk truck for about 3 hrs. However the loss was considerable when placed in the shade, and even greater when the milk was placed in sunlight. Rapid destruction of all ascorbic acid in milk either by exposure to sunlight or through the addition of 30% H2O2 resulted in no oxidized flavors over a 5-day storage period.