Effect of white grape extract and modified atmosphere packaging on lipid and protein oxidation in chill stored beef patties.

The oxidative stability of beef patties added 500ppm white grape extract (WGE), packed in four different modified atmospheres (MAP) with varying oxygen and carbon dioxide levels (70% or 0% O2, 30% or 0% CO2, balanced with N2 in all four combinations) and stored for up to 9days (4°C) was evaluated by a sensory panel, formation of TBARS, formation of protein carbonyl, appearance of myosin cross-links, and thiol loss. Formation of secondary lipid oxidation products, as detected by TBARS, and the rancidity, as perceived by sensory analysis, were inhibited in WGE beef patties independent of MAP compared to control beef patties. The protein carbonyl formation was also reduced in WGE beef patties, but no significant effects were observed in relation to different MAP. Loss of thiol groups in control beef patties was consistent with the formation of myosin cross-linkages. In the presence of WGE, thiol groups decreased faster but showed less myosin cross-link formation compared to control beef patties, indicating that WGE interacts with the thiol groups of the myofibrillar proteins, and thus reduces the cross-link formation in beef patties stored in high-oxygen MA.