Structural changes of concentrated milk with sugar in the course of long storage

Concentrated canned milks with sugar occupy a special place in the list of food products with extended shelf life due to their long storage, efficiency of production and high positions according to the consumers demand in Russia. Trials nave been carried out with the aim to study additional quality indices such as dispersibility of the lipid phase and forecast of stability against consistency defects (separation of layers, thickening) in the concentrated milk with sugar and dehydroquercetine. Analysis were made before placing the products for storage and during the further the storage after 6, 12, 15, 18, 21, 24 and 29 months. The task was to study possible effects of dehydroquercetine added to the product in the quantities of 0,02 and 0,04 % of the fat mass on the physical and physical-chemical processes of the structure changes. It can lead to changes in the homogeneity of composition as compared with control samples without dehydroquercetine during long storage at two regimes of the average year temperatures: 12 and 3 °C. No considerable changes in the lipid phase were found both in the control and trial samples of the product in the course of the entire storage time. Fat globes were isolated from each other, average size did not practically exceed 2 milimicrones. Efficiency of homogenization has been constantly lowering: from 80% before placing for storage to 40-50 % after 29 months storage. The data received show correlation between changes in homogenization efficiency and product viscosity as well as storage temperature. The values of dynamic viscosity were in the range of 3-15 Pa/sec and in spite of some natural increase they did not exceed allowed limits. After extreme temperatures effects at certain stability against thickening viscosity in the samples normally increased (actually 2 times). However, in the course of further storage the product consistency did not change considerably. No significant thickening was observed. Flowability remained at the same level. It was found that dispersibility of lipid phase, stability against layers separation and thickening in the control and trial samples did not change significantly during the entire period of the study.

canned milk products, concentrated milk with sugar, extended storage, dispersibility of the lipid phase, dymanic viscosity, layers separation, thickening, efficiency of homogenization, dehydroquercetine