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

under acidic <strong>and</strong> alkal<strong>in</strong>e conditions. Conversely, mass balance of crude prote<strong>in</strong> was reduced <strong>in</strong>variety HiC7 <strong>and</strong> HiC23 under acidic <strong>and</strong> alkal<strong>in</strong>e conditions, respectively.Tables 5.6 <strong>and</strong> 5.7 present mass balance of carotenoid pigments <strong>and</strong> the significance offactors applied, respectively. Mass balance of pigments <strong>in</strong> corn gluten meal produced from bothkernel varieties showed a general reduction trend to hydrogen peroxide level under both acidic<strong>and</strong> alkal<strong>in</strong>e conditions.5.4 DiscussionBleach<strong>in</strong>g of yellow carotenoids from corn gluten meal was assessed us<strong>in</strong>g a laboratoryscalewet mill<strong>in</strong>g process. Hydrogen peroxide, a bleach<strong>in</strong>g agent widely utilized for colourreduction <strong>in</strong> cellulosic <strong>and</strong> dairy products (Zeronian <strong>and</strong> Inglesby, 1995; Abdel-Aal et al., 1996;Kang et al., 2010) was <strong>in</strong>cluded <strong>in</strong> steepwater <strong>and</strong> applied under either acidic (pH~2) or alkal<strong>in</strong>e(pH~11) conditions. Two different corn kernel varieties were chosen based on their highcarotenoid content <strong>and</strong> composition (Table 5.1).The wet mill<strong>in</strong>g process used <strong>in</strong> this trial allowed the separation of corn kernels <strong>in</strong>to fivedifferent fractions (i.e. starch, gluten, germ, fiber <strong>and</strong> solids <strong>in</strong> steepwater). Yield of solids <strong>in</strong>steepwater obta<strong>in</strong>ed <strong>in</strong> this trial did not show a clear trend <strong>and</strong> values were high (rang<strong>in</strong>g from6% to 17%) compared to those previously reported for this fraction (Zehr et al., 1995). Thisresult suggests that large amounts of soluble compounds from corn kernels were leached <strong>in</strong>tosteep water dur<strong>in</strong>g the course of steep<strong>in</strong>g.Yields of germ <strong>and</strong> fiber fractions obta<strong>in</strong>ed <strong>in</strong> this trial (Table 5.2) were similar to thoseregularly achieved dur<strong>in</strong>g <strong>in</strong>dustrial operations. H<strong>and</strong>-dissection for hull <strong>and</strong> germ removalapplied <strong>in</strong> this study most probably led to an efficient isolation of these fractions. Yields of114