Research of milk fat oxidation processes during storage of butter pastes

Abstract

Basic quality indicators studied: acidity, peroxide, anisidine value and integrated value of complete fat oxidation. Butter paste was selected as a reference, consisting of butter, skim milk powder and fat-soluble emulsifiers. Peroxide value during storage at the temperature of (4 ±2 °С) for the first 4 days did not exceed 5.0 1/2 О mmol.kg-1, on the 15th day fat peroxide value of butter paste with milk-vegetable protein exceeded permissible limits that is indicative of milk fat contamination. At the temperature of (-3 ±1 °С) butter paste fat couldn't be qualified as fresh when storing during 15 days, peroxide value exceeds permissible limits on the 25th day of storage. Rising of the peroxide value above 5 1/2 О mmol.kg-1 was detected on the 25th day of storage, exceeding of threshold value was on the 45th day. It was established that rate of oxidation processes in butter pastes with vegetable protein is the highest among all studied samples in each particular control and observation point. It was determined that the rate of secondary lipid oxidation depends on the storage temperature and is observed when storing butter paste samples at a temperature of (-3 ±1 °С) on the 10th day, (-24 ±2 °С) – on the 30th day of storage. Acid value did not exceed recommended limits (2.5 °K) and was on average – 2.3 °K when storing butter paste during 10 days at a temperature of (4 ±2 °С); 2.1 °K during 20 days at the temperature of (-3 ±1 °С), 2.4 °K during 40 days at the temperature of (-24 ±2 °С). In view of obtained results of fat phase stability evaluation of studied butter pastes, the following storage maximum time is recommended: at the temperature of (4 ±2 °С) ‒ 7 days, at the temperature of (-3 ±1 °С) – 15 days, at the temperature of (-26 ±2 °С) ‒ 30 days.