ABSTRACT
Lipid oxidation is one of the main causes of deterioration in the quality of meat during storage and processing (Gandemer 2002). The main process of lipid oxidation in meat and meat products is a chemical process named autooxidation. Ground meat has greater autooxidation potential than whole cuts because the grinding process incorporates oxygen, mixes reactive components, and increases surface area as a result of particle size reduction. Also, some lipid compounds like phospholipids are very susceptible to autooxidation due to its high content in PUFA. Flavorless hydroperoxides are the primary products of oxidation, while the secondary products of oxidation can contribute to off flavors, color deterioration, and potential generation of toxic compounds (Faustman et al. 2010). Lipid and protein oxidation may also be induced by hydrogen peroxide generated by certain bacteria during meat fermentation. Some products of lipid oxidation may be chronic toxicants but the low levels (usually present in sausages) are far from any acute toxicity. Cholesterol oxidation may occur resulting in formation of cholesterol oxides which are considered as prejudicial for health but no cholesterol oxides have been detected after heating of pork sausages. Studies made on European sausages (based on in vivo tests with laboratory animals) revealed that the content of cholesterol oxides were quite below toxic. Sulfur amino acids of proteins are those more susceptible to oxidation by peroxide reagents, thus cystine is oxidized to sulfinic and cysteic acids, whereas methionine is oxidized to methionine sulfoxide and methionine sulfone (Gallego et al. 2015). Homolanthionine sulfoxide is the main product of homocysteine oxidation. Peptides like the reduced glutathione can also be oxidized by hydrogen peroxide and most of the cysteine in the glutathione is oxidized to the monoxide or dioxide forms (Toldrá and Reig 2007). The formation of carbonyl compounds from specific amino acids (like lysine, arginine and proline) is one of the most remarkable measurable changes in oxidized proteins and has been commonly used as indicator of protein oxidation in food (Utrera et al. 2011).
