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Some Factors Affecting the Keeping Quality of Whole Milk Powders

1924; Elsevier BV; Volume: 7; Issue: 1 Linguagem: Inglês

10.3168/jds.s0022-0302(24)93993-2

1529-9066

C.D. Dahle, L. S. Palmer,

Food Quality and Safety Studies

Summary A study of the keeping quality of 216 samples representing three types of whole milk powders is described as follows: Powders whose moisture content was increased by exposing the powders to moist air exhibited very inferior keeping qualities. Oxidation of the fat, giving rise to a tallowy odor, was the cause of deterioration. Containers in which the powders were stored greatly influenced the keeping quality. Containers permitting the entrance of air proved to be useless for long time storage. Deterioration was very pronounced in the samples stored in these containers, the extent of deterioration was usually more marked in case of the Creamora and Creamon A powders. Klim powder is not exposed to as much air as either of the other powders in the package. It has smaller individual powder grains which permit closer packing than Creamora A and Creamon, and the air cell when present within the powder grain is much smaller than that of the other spray powder, Creamon. Superior keeping quality was observed in samples of powders stored in tin Doubletite containers. These containers provided for absolute exclusion of outside air and moisture. In some cases samples were practically unchanged after a year in storage. Protection against discoloration, due to high storage temperature, was afforded when this type of container was used. This was not the case when other containers were used. Lacquered tin containers afforded no better protection than the unlacquered. In most instances the keeping quality was inferior to powders stored in the unlacquered tins. Pasteboard containers proved to be unsatisfactory, since air and moisture gained access to the powder. Tallowy and musty flavors were the main deteriorations observed. The temperature at which the powders were stored proved to be an important factor. Not a great deal of difference was observed between powders stored at 4° and 20°C, but a great difference was observed when powders were stored at 37°C. Most of these powders deteriorated very rapidly at this temperature and became very hard and discolored. The powders stored in the tin containers Doubletite did not become discolored, and the deterioration was not so pronounced as in cases where other containers were used. The influence of the time of storage depends on factors such as type of containers used and temperature of storage. Powders stored in opaque glass containers with screw tops and those in paste board containers showed signs of deterioration after three months in storage, while some powders stored in tin Doubletite containers showed scarcely no deterioration after one year in storage at 4° and 20°C. All powders stored at 37°C. showed pronounced deterioration at the time the first examination was made, or after three months in storage.