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Some Observations on the Keeping Quality of Spray-Dried Whole Milk Stored at Room Temperature

1945; Elsevier BV; Volume: 28; Issue: 9 Linguagem: Inglês

10.3168/jds.s0022-0302(45)95223-4

1529-9066

J.H. Hetrick, P.H. Tracy,

Microencapsulation and Drying Processes

Oxidative deterioration of dried whole milk powder has been commonly attributed to the oxidation of the fat fraction.Our knowledge of the specific reactions involved is not complete, but the research work of various investigators has indicated that copper contamination of the milk and certain factors in processing, packing, and storage of whole milk powder are related to the shelf life of the product. REVIEW OF LITERATUREHolm and Greenbank (7) concluded from studies on the susceptibility of pure butterfat to oxidation that the quality of the milk from which the powder is made determines to some extent the keeping quality of the powder.Forewarming the milk at higher than the ordinary preheating temperature (83 ° C. for 30 minutes) was found by Holm, Greenbank and Deysher (9) to improve the keeping quality of the powder, which i's. consistent with the findings of Jack and Henderson (11).Hollender and Tracy (6) have indicated that powder made from milk heated to 170 ° F. for 30 minutes is less likely to develop an oxidized flavor during storage than that made from milk heated to a higher (190 ° F.) or lower (150 ° F.) temperature for the same length of time.Experinients by Holm, Greenbank and Deysher (9) showed that clarification of the milk improved the keeping quality of milk powder.It was thought that some enzymes or catalysts were removed by this treatment because returning the separator slime to the clarified milk resulted in a product with as poor a keeping quality as that made from unclarified milk.They suggested that the better keeping quality of cream powder over whole milk powder as observed by Supplee (17), may result froui the beneficial effect of centrifugal separation.Hohn, Greenbank and Deysher (8) found that powder made from precondensed milk possessed better keeping quality than that made from uncondensed milk.They suggested that the removal during condensing of some volatile substances which act as catalysts may be the contributing factor in increasing the resistance of the fat to oxidation.Their results also showed that milk powder made from milk which was homogenized had better keeping quality than that made from unhomogenized milk.The importance of the catalytic effect of copper on the development of tallowiness in milk powder has been shown by the work of Supplee (17).