Pigment Reduction in Corn Gluten Meal and Its Effects on Muscle ...

leached when 5% of soy flour as LOX source was mixed with wet CGM <strong>in</strong> an aqueous mediumat pH 6.5 (Cha et al., 2000; Park et al., 1997).The aims of this literature review are 1) to contribute to a better underst<strong>and</strong><strong>in</strong>g on the effectsof <strong>in</strong>clusion of plant-prote<strong>in</strong> <strong>in</strong>gredients, specifically corn gluten meal, on muscle quality traitssuch colour <strong>and</strong> 2) to <strong>in</strong>troduce some practical process<strong>in</strong>g methods for corn gluten meal <strong>in</strong> orderto reduce its pigment content <strong>and</strong> reduce its negative effect on muscle pigmentation of salmonidfish.2.2 Evolution of diet formulation for salmonid fish <strong>and</strong> flesh quality assessmentHistorically, aquaculture feeds have relied upon fish meal as a major prote<strong>in</strong> source due tothe high nutritive value of this commodity. Production of salmonid feed has shown a fast growth<strong>in</strong> the last decade, the annual global production of formulated diets for salmonid fish <strong>in</strong> 2006 wasestimated at about 2.6 MMT (Tacon <strong>and</strong> Metian, 2009). The steady <strong>in</strong>crease of price <strong>and</strong> variableavailability of fisheries by-products observed dur<strong>in</strong>g the last three decades had forced salmonidfeed formulators to <strong>in</strong>crease <strong>in</strong>clusion levels of more available <strong>and</strong> cost-effective feed <strong>in</strong>gredients<strong>in</strong> order to manage their production costs.Ingredients which have found wide use <strong>in</strong> aquaculture feeds are poultry by-product meal,meat <strong>and</strong> bone meal, soybean meal, soy prote<strong>in</strong> concentrates <strong>and</strong> corn gluten meal (Alexis et al.,1985; Cha et al., 2000; de Francesco et al., 2004). Numerous scientific studies assess<strong>in</strong>g theeffects of these <strong>in</strong>gredients (<strong>and</strong> many other new potentially useful ones) on growth, digestibility<strong>and</strong> nutrient retention have been published <strong>in</strong> the last decades. On the other h<strong>and</strong>, only a fewscientific publications address<strong>in</strong>g the effects of these commodities on flesh quality <strong>in</strong> salmonidfish are available. Inclusion of soy prote<strong>in</strong> concentrate <strong>and</strong> soybean meal (62 <strong>and</strong> 42% <strong>in</strong>clusion6