The influence of storage time on lipids oxidation processes in frozen pork | Uticaj vremena skladištenja na tok lipidne oksidacije u zamrznutom svinjskom mesu

Standards for storage time of frozen meat in relation to types of meat, storage temperature or meat pretreatment are lacking in Serbia. Meat storage induces oxidative changes of lipids. In this study, pork was classified into categories followed by determination of oxidative changes in lipids and fatty acids and content of cholesterol of classified meats with higher fat content. Frozen at -30 deg C, and stored at -20 deg C, these categories were monitored during one year period. The oxidative changes were monitored through the concentration of malonildialdehyde (MDA). After 3 months of storage, MDA value has not significantly changed. After the 6 months period of storage, MDA value increased in all samples in the interval of 0.41-0.54 mg/kg. After 9 months, samples of category 3rd, 4th and 5th contained 0.75 mg/kg, 0.83 mg/kg and 1.36 mg/kg of MDA respectively. Oxidative changes observed up to the 6th month of storage are considered as acceptable, however, the longer storage period resulted in increase (p is less than 0.001) of lipid peroxydation. During storage the ratio of unsaturated and saturated fatty acids decreased significantlyntly (p is less than 0.001) in all investigated samples. Cholesterol content in the samples before freezing is not closely related to the content of free fat. The lowest cholesterol content (59.5 mg/100g) was found in the meat category 3rd, while the highest cholesterol content (61.1 mg/100g) was determined in the meat category 4th. During 12 months of storage, content of cholesterol decreased significantly (p is less than 0.001), in all investigated samples. The obtained results confirm that the degree of lipid peroxydation depends on the storage time and fat content of meat and points to the necessity for harmonization of national regulations with the international ones.