ABSTRACT

Important food components such as unsaturated lipids, proteins, and vitamins are very prone to undergoing oxidative deterioration during processing and storage. Although several of these food constituents suffer important autoxidative reactions under certain conditions, in most foods, the rate and extent of oxidation are highly conditioned by the concentration and activity of oxidizing agents, which can be natural components of foods, food additives, and even substances generated during processing or storage. Food oxidation regularly causes a decrease in consumer acceptance, but in some cases, oxidative reactions of specic food components lead to an improvement in the product quality. An example is the enzymatic oxidation of polyunsaturated fatty acids (PUFAs) by lipoxygenases (LOXs) that is responsible for the fresh aromas in sh and vegetables or the oxidation developed during the ripening of several appreciated salted sh products that are related with the characteristic organoleptic properties of these foods (Andersen, Andersen and Baron 2007). On the contrary, the activity of oxidants, such as redox active metals and hemoproteins, on PUFA generates rancid off-avors and diminishes nutritive value during processing and storage. This oxidative deterioration of PUFA dramatically restricts shelf life and consumer acceptance in a large variety of foodstuffs, such as meat, sh, milk products, and new functional products enriched in PUFA n-3. Therefore, the identication of the

2.1 Introduction .................................................................................................... 21 2.2 Nonenzymatic Oxidants .................................................................................22