Effect of olive leaf (Olea europea L.) extracts on protein and lipid oxidation of long-term frozen n-3 fatty acids-enriched pork patties

• Frozen storage increase primary and secondary lipid oxidation products in n-3 pork.
• Frozen storage increase protein carbonyls and decrease sulphydryls in n-3 patties.
• Olive leaf extract (OLE) at 100 mg GAE/kg has no antioxidative activity in patties.
• OLE at 200 or 300 mg GAE/kg inhibit lipid and protein oxidation in patties.

Our previous study has demonstrated the protective effects of olive leaf extracts on the oxidation of pork patties from n−3 fatty acid-enriched meat during refrigerated storage. The target of the present study was to examine these effects during frozen storage. Results showed that frozen storage accelerated (P = 0.05) both lipid and protein oxidation in pork patties, but an addition of olive leaf extract at 200 mg gallic acid equivalent/kg improved sensory attributes by delaying oxidation of lipids (reduction (P = 0.05) of conjugated dienes, hydroperoxides and malondialdehyde), and of proteins (reduction (P = 0.05) of protein carbonyls and inhibition (P = 0.05) of the decrease of protein sulfhydryls).