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

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CHAPTER - 5 BLEACHING OF CAROTENOIDS FROM CORN GLUTEN MEALTHROUGH A MODIFIED STEEPING PROCESS TO IMPROVE ITS VALUE AS ASALMONID FISH INGREDIENT: EFFECTS OF KERNEL VARIETY, HYDROGENPEROXIDE AND STEEPWATER PHAbstract<str<strong>on</strong>g>Corn</str<strong>on</strong>g> gluten meal (CGM) is a highly digestible <str<strong>on</strong>g>in</str<strong>on</strong>g>gredient comm<strong>on</strong>ly used <str<strong>on</strong>g>in</str<strong>on</strong>g> diets forsalm<strong>on</strong>ids. However the use of significant (>12%) levels of this <str<strong>on</strong>g>in</str<strong>on</strong>g>gredient has been related toreducti<strong>on</strong> <str<strong>on</strong>g>in</str<strong>on</strong>g> pigment depositi<strong>on</strong> <str<strong>on</strong>g>in</str<strong>on</strong>g> muscle of ra<str<strong>on</strong>g>in</str<strong>on</strong>g>bow trout (Oncorhynchus mykiss), possibly dueto negative effects of yellow xanthophylls <strong>on</strong> astaxanth<str<strong>on</strong>g>in</str<strong>on</strong>g> depositi<strong>on</strong> <str<strong>on</strong>g>in</str<strong>on</strong>g> the muscle. Cost effectivemethods for decreas<str<strong>on</strong>g>in</str<strong>on</strong>g>g the level of yellow xanthophylls <str<strong>on</strong>g>in</str<strong>on</strong>g> corn products may improve theirvalue as a fish feed <str<strong>on</strong>g>in</str<strong>on</strong>g>gredient. A laboratory-scale (10 g) corn wet mill<str<strong>on</strong>g>in</str<strong>on</strong>g>g procedure was used toassess the bleach<str<strong>on</strong>g>in</str<strong>on</strong>g>g of carotenoids from CGM dur<str<strong>on</strong>g>in</str<strong>on</strong>g>g steep<str<strong>on</strong>g>in</str<strong>on</strong>g>g. Kernels from two maize (Zeamays L) varieties (HiC7 <str<strong>on</strong>g>and</str<strong>on</strong>g> HiC23 rich <str<strong>on</strong>g>in</str<strong>on</strong>g> lute<str<strong>on</strong>g>in</str<strong>on</strong>g> <str<strong>on</strong>g>and</str<strong>on</strong>g> zeaxanth<str<strong>on</strong>g>in</str<strong>on</strong>g>, respectively) were used <str<strong>on</strong>g>in</str<strong>on</strong>g> thistrial. Hydrogen peroxide was added <str<strong>on</strong>g>in</str<strong>on</strong>g>to steepwater at 0, 0.15 or 0.30 M under either acidic (pH~2) or alkal<str<strong>on</strong>g>in</str<strong>on</strong>g>e (pH ~8) c<strong>on</strong>diti<strong>on</strong>s. <str<strong>on</strong>g>Corn</str<strong>on</strong>g> kernels were steeped for 48 h at 52 °C. About 50% oftotal determ<str<strong>on</strong>g>in</str<strong>on</strong>g>ed carotenoids were bleached dur<str<strong>on</strong>g>in</str<strong>on</strong>g>g steep<str<strong>on</strong>g>in</str<strong>on</strong>g>g for the two kernel varieties at 0.30 Mof hydrogen peroxide c<strong>on</strong>centrati<strong>on</strong> under acidic c<strong>on</strong>diti<strong>on</strong>s (pH~2). <str<strong>on</strong>g>Corn</str<strong>on</strong>g> variety significantlyaffected bleach<str<strong>on</strong>g>in</str<strong>on</strong>g>g of all pigments determ<str<strong>on</strong>g>in</str<strong>on</strong>g>ed except for all-trans β-carotene. Steepwater pH hada significant effect <strong>on</strong> all-trans zeaxanth<str<strong>on</strong>g>in</str<strong>on</strong>g> <str<strong>on</strong>g>and</str<strong>on</strong>g> all-trans β-cryptoxanth<str<strong>on</strong>g>in</str<strong>on</strong>g>. Hydrogen peroxideadditi<strong>on</strong> <str<strong>on</strong>g>in</str<strong>on</strong>g>to steepwater significantly affected all yellow carotenoids m<strong>on</strong>itored. Mass balancefor total carotenoid determ<str<strong>on</strong>g>in</str<strong>on</strong>g>ed <str<strong>on</strong>g>in</str<strong>on</strong>g> corn gluten meal showed no significant effect of corn variety,suggest<str<strong>on</strong>g>in</str<strong>on</strong>g>g that bleach<str<strong>on</strong>g>in</str<strong>on</strong>g>g rates were proporti<strong>on</strong>al to the <str<strong>on</strong>g>in</str<strong>on</strong>g>itial pigment c<strong>on</strong>tent <str<strong>on</strong>g>in</str<strong>on</strong>g> the kernels.Scal<str<strong>on</strong>g>in</str<strong>on</strong>g>g-up of this procedure (us<str<strong>on</strong>g>in</str<strong>on</strong>g>g commercial-scale equipment) is necessary <str<strong>on</strong>g>in</str<strong>on</strong>g> order to assess105

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