Effect of grape seed and rosemary phenolics on protein oxidation in Chinese-style sausage

Chinese-style sausage is a very popular meat product obtained from a mixture of chopped pork meat, lard, salt, spices, additives (nitrate, nitrite, and antioxidants) and/or starter cultures. In terms of nutrition, sausage is an important source of proteins with a high biological value; however, this product has certain negative effects because of oxidation. The oxidation of muscle protein leads to the loss of essential amino acids and affected protein functionality and food quality. This study investigated the antioxidative effect of grape seed phenolic and rosemary phenolic on protein oxidation in Chinese-style sausage compared with that of butylated hydroxy toluene (BHT) and ursolic acid. Through pork lipid oxidation pre- experiment, the optimum adding amount of antioxidants were determined. Lipid oxidation and protein oxidation of sample sausages were evaluated during ripening and 75 days storage. The correlation between nonheme iron and the overall effect of antioxidants was studied. At the optimum adding amount, grape seed phenolic (0.1% in total fat, w/w) and rosemary phenolic (0.05% in total fat, w/w) was more effective than BHT (0.015% in total fat, w/w) and ursolic acid (0.05% in total fat, w/w) in inhibiting lipid oxidation in sample Chinese-style sausage. Moreover, grape seed phenolic showed the highest capability in inhibiting protein oxidation in sample Chinese-style sausages. The effectiveness of the antioxidant activity in inhibiting protein oxidation exhibited by grape seed phenolic was correlated with its inhibiting ability on metmyoglobin formation by competitively chelating iron from myoglobin. This study reveals a potential application of grape seed phenolic to enhance the oxidation stability of meat products during long storage.