Oxidative Stability of Seafood
Being a threat to almost any aspect of seafood quality-nutritional properties, odor, taste, texture, and color-lipid oxidation is of utmost importance to control within the seafood industry. Differences in the endogenous pools of lipids and pro- and antioxidants, including their direct contact with each other and with air, explain why different aquatic raw material species, products, and morphological parts vary largely in their sensitivity toward oxidation. In fish tissue, the presence and activation of heme proteins as pro-oxidants appear to be particularly crucial in triggering oxidation. The chain of events leading from the harvest/slaughter up to the final product indeed also largely influences oxidation, with examples of critical points being the degree of stress during catch/slaughter, bleeding, washing, precooking and potential oxygen removal during packing. In attempts to add value to underused aquatic species and byproducts-a large focus area today-alternative processing techniques like enzymatic hydrolysis and pH-shift processing have also entered the scene, but it is obvious that care must here be taken to avoid oxidation. The same applies to the incorporation of alternative raw materials like algae and krill into seafood; little is here known about their intrinsic oxidation mechanisms. To combat oxidation in seafood, the addition of plant extracts or pure phenolic compounds is currently receiving huge attention, but also muscle-derived extracts appear interesting as all-natural stabilizers. The current chapter addresses these topics based on both recent literature and core older studies to give a comprehensive picture.