Protein Oxidation in Muscle Foods: A Comprehensive Review

Abstract

Muscle foods and their products are a fundamental part of the human diet. The high protein content found in muscle foods, as well as the high content of essential amino acids, provides an appropriate composition to complete the nutritional requirements of humans. However, due to their special composition, they are susceptible to oxidative degradation. In this sense, proteins are highly susceptible to oxidative reactions. However, in contrast to lipid oxidation, which has been studied in depth for decades, protein oxidation of muscle foods has been investigated much less. Moreover, these reactions have an important influence on the quality of muscle foods, from physico-chemical, techno-functional, and nutritional perspectives. In this regard, the loss of essential nutrients, the impairment of texture, water-holding capacity, color and flavor, and the formation of toxic substances are some of the direct consequences of protein oxidation. The loss of quality for muscle foods results in consumer rejection and substantial levels of economic losses, and thus the control of oxidative processes is of vital importance for the food industry. Nonetheless, the complexity of the reactions involved in protein oxidation and the many different factors that influence these reactions make the mechanisms of protein oxidation difficult to fully understand. Therefore, the present manuscript reviews the fundamental mechanisms of protein oxidation, the most important oxidative reactions, the main factors that influence protein oxidation, and the currently available analytical methods to quantify compounds derived from protein oxidation reactions. Finally, the main effects of protein oxidation on the quality of muscle foods, both from physico-chemical and nutritional points of view, are also discussed.

Keywords: analytical methods; carbonyls; fish and fish products; food quality; meat and meat products; oxidative stress; protein cross-linking.

Figure 1

Schematic representation of the main mechanisms and factors that affect protein oxidation, different analytical methods for quantifying protein oxidation, and the detrimental effects of protein oxidation on muscle food quality.

Figure 2

Schematic representation of the mechanism of protein oxidation.

Figure 3

Proposed mechanism of action for salt (NaCl) and protein oxidation.

Figure 4

(a) Derivatization of carbonyl group with DNPH; (b) Derivatization of thiol group with DTNB; (c) Derivatization of thiol group with 4-DPS.