Intensity of lipid oxidation and formation of cholesterol oxidation products during frozen storage of raw and cooked chicken

Raw and cooked chicken breasts were stored at −18 °C for 3 months under aerobic and vacuum conditions, and the intensity of lipid oxidation and the formation of COP (cholesterol oxidation products) were studied. Raw samples showed low COP levels (4.60–7.40 µg g−1 fat), TBARS (thiobarbituric acid reactive substances) levels (0.01–0.03 mg kg−1) and peroxide values (not detected) under both aerobic and vacuum conditions. Cooked samples (grilled and roasted) showed TBARS levels of 0.36–0.99 mg kg−1 in aerobic conditions and 0.21–0.70 mg kg−1 in vacuum conditions, whilst peroxide levels reached 38–40 and 19–23 meq O2 kg−1 in samples stored under aerobic and vacuum conditions respectively. Total COP levels in grilled and roasted samples were 28.91 and 39.34 µg g−1 fat in aerobic packaging and 4.90 and 20.24 µ g g−1 fat in vacuum packaging respectively. Significant correlations were found between the lipid oxidation parameters and cholesterol oxidation indices. In general, TBARS were better correlated with total COP than with only 7-ketocholesterol. Vacuum packaging was particularly efficient in slowing down the oxidation process during frozen storage of cooked sample