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

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gluten meal fraction achieved <strong>in</strong> this study (Table 5.2) were about 1.6 to 4.1 folds higher (<strong>and</strong>yields of starch were 0.8 to 2.0 folds lower) than those previously reported for experimental cornwet mill<strong>in</strong>g procedures (Zehr et al., 1995; Eckhoff et al., 1996; S<strong>in</strong>gh et al., 1997; Dowd, 2003).These results suggest an <strong>in</strong>complete separation of the starch <strong>and</strong> prote<strong>in</strong> fractions.With<strong>in</strong> kernel endosperm, starch particles are embedded <strong>in</strong> prote<strong>in</strong> matrixes; sulfur dioxide<strong>and</strong> lactic acid dissolved <strong>in</strong> steepwater promotes the breakdown of disulfide bonds <strong>in</strong> prote<strong>in</strong>s,thus promot<strong>in</strong>g the release of starch (Krochta et al., 1981; Eckhoff et al., 1999). Low starchyields obta<strong>in</strong>ed <strong>in</strong> a laboratory-scale (10 g) wet mill<strong>in</strong>g process were related to non-uniformgr<strong>in</strong>d<strong>in</strong>g (Vignaux et al., 2006).Yields of starch <strong>and</strong> gluten fractions typically obta<strong>in</strong>ed under<strong>in</strong>dustrial conditions are difficult to replicate under bench-scale laboratory conditions ma<strong>in</strong>ly dueto equipment limitations. Moreover, high-prote<strong>in</strong> corn kernels have been correlated with highernumbers of prote<strong>in</strong> matrixes embedd<strong>in</strong>g starch (Vignaux et al., 2006), thus limit<strong>in</strong>g the release ofstarch granules. The high crude prote<strong>in</strong> level conta<strong>in</strong>ed <strong>in</strong> kernel varieties utilized <strong>in</strong> this trial(Table 5.1) might partially expla<strong>in</strong> the results from this trial.Incomplete separation of starch <strong>and</strong> prote<strong>in</strong> fractions obta<strong>in</strong>ed <strong>in</strong> this study can beattributed to mill<strong>in</strong>g shortcom<strong>in</strong>gs associated with equipment limitations. These shortcom<strong>in</strong>gsprobably did not have an effect on pigment reduction <strong>in</strong> the gluten fraction which is the ma<strong>in</strong>objective of this study.Increase of hydrogen peroxide concentration under acidic conditions led to lower gluten,<strong>and</strong> higher starch yields (Table 5.2). The effect of hydrogen peroxide on prote<strong>in</strong> oxidation <strong>in</strong>biological systems is very well documented (Stadtman <strong>and</strong> Lev<strong>in</strong>e, 2000). The highconcentration of hydrogen peroxide (0.03 M) used <strong>in</strong> this trial might have <strong>in</strong>duced prote<strong>in</strong>115
oxidation with<strong>in</strong> the endosperm of kernels <strong>and</strong> consequently improved millability of the prote<strong>in</strong>matrix.Total starch <strong>and</strong> crude prote<strong>in</strong> content <strong>in</strong> the starch fraction ranged from 81% to 93% <strong>and</strong>from 0.2% <strong>and</strong> 0.3%, respectively. On the other h<strong>and</strong>, total starch <strong>and</strong> crude prote<strong>in</strong> <strong>in</strong> the glutenfraction varied from 24% to 26% for all the treatments <strong>in</strong> this trial (Table 5.3). Substantialamounts of starch <strong>and</strong> low crude prote<strong>in</strong> level <strong>in</strong> the gluten fraction are consistent with the<strong>in</strong>complete separation of this fraction obta<strong>in</strong>ed <strong>in</strong> this trial. However, commercial corn glutenmeals with higher total starch content have been previously reported <strong>in</strong> the literature (Ji et al.,2012).Carotenoid profiles determ<strong>in</strong>ed for the high carotenoid corn varieties utilized <strong>in</strong> this studywere <strong>in</strong> the same range of those previously reported for these types of kernels (Burt et al., 2011)<strong>and</strong> higher than those reported for regular corn gra<strong>in</strong>s (Moros et al., 2002). HiC7 varietyconta<strong>in</strong>ed high levels of all-trans lute<strong>in</strong> content (58 mg kg -1 ) <strong>and</strong> a total pigment concentration of102 mg kg -1 , whereas HiC7 variety conta<strong>in</strong>ed high levels of all-trans zeaxanth<strong>in</strong> (56 mg kg -1 ) <strong>and</strong>a total carotenoid content of 84 mg kg -1 (Table 5.1).Carotenoid profiles of the corn gluten meal fraction produced us<strong>in</strong>g steepwater with nohydrogen peroxide <strong>in</strong>clusion under acidic conditions (Table 5.4) were <strong>in</strong> the range of thosereported for commercial corn gluten meal (Moros et al., 2002). Differences <strong>in</strong> carotenoidcomposition among corn gluten meals obta<strong>in</strong>ed from different corn kernel varieties reflectedpigment composition of corn gra<strong>in</strong>s utilized <strong>in</strong> this study (Table 5.1).Concentration of hydrogen peroxide <strong>in</strong> steepwater significantly affected carotenoidpigment reduction <strong>in</strong> corn gluten meal (Table 5.4). The effectiveness of hydrogen peroxide on116
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Pigment Re
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ingredients. Furth
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Thanks to all my colleagues, friend
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2.10.1 Enzymatic treatments .......
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LIST OF TABLESTable 3. 1 - Factors
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LIST OF FIGURESFigure 2. 1 - Molecu
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Ingredients commonly in</st
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CHAPTER - 2 LITERATURE REVIEW2.1 In
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leached when 5% of soy flour as LOX
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deep and fast glyc
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observed in ra<str
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Chylomicron constituents are remove
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Muscle growth in r
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2.7.2 Corn gluten
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2010). However, due to its imbalanc
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No differences in
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supplemented with 42% of a vegetabl
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Soybean seeds are the richest known
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2.10.1.4 Bleaching
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2.11 ConclusionInclusion of <strong
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4.0%*68%* 5.6%* 12%* 3.5%* 6.5%*Fig
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Figure 2. 4 - Schematic representat
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3.1 IntroductionThe characteristic
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many factors such as LOX source lev
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During the 12-week
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3.2.3 Analytical methodsDry matter
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solution was generated by mix<stron
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3.2.4 Statistical analysisData from
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Factors defined as
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chromatography). Relative amounts o
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After carotenoids are absorbed thro
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and ended up <stro
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Table 3. 2 - Experimental design us
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Table 3. 4 - Analysed proximate com
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Proximate composition (Analysed; dr
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Table 3. 7 - Lipoxygenase activity
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18 1 0 -1 0 120 15 0 10 2519 -1 0 1
Page 75 and 76: Table 3. 10 - HPLC carotenoid profi
Page 77 and 78: Table 3. 12 - Retain</stron
Page 79 and 80: Table 3. 14 - Fillet carotenoid con
Page 81 and 82: Total yellow pigment(mg•kg -1 )25
Page 83 and 84: Figure 3. 4 - Growth curve of ra<st
Page 85 and 86: effects of dietary CGM and<
Page 87 and 88: soybean meal in a
Page 89 and 90: were randomly samp
Page 91 and 92: An aliquot (1 ml) of chloroform low
Page 93 and 94: Retained nitrogen
Page 95 and 96: significant (p
Page 97 and 98: Values for all-trans astaxanth<stro
Page 99 and 100: previous reports where colour attri
Page 101 and 102: Proximate composition (analysed), d
Page 103 and 104: Table 4. 2 - Growth performance of
Page 105 and 106: Table 4. 3 - Carcass chemical proxi
Page 107 and 108: Table 4. 4 - Retain</strong
Page 109 and 110: Table 4. 5 - Pigment</stron
Page 111 and 112: Table 4. 6 - Colour attributes <str
Page 113 and 114: FiguresFigure 4. 1 - Growth curves
Page 115 and 116: Figure 4. 3 - Muscle colour attribu
Page 117 and 118: the effects of dietary reduced-caro
Page 119 and 120: astaxanthin deposi
Page 121 and 122: After steeping, ke
Page 123 and 124: 0.9994 and 0.9999,
Page 125: under acidic and a
Page 129 and 130: colour difference usin</str
Page 131 and 132: TablesTable 5. 1 - Analyzed proxima
Page 133 and 134: Effects of
Page 141 and 142: Data are mean (n=2).a Steepwater pH
Page 143 and 144: CHAPTER - 6 GENERAL DISCUSSIONCurre
Page 145 and 146: significant reduction in</s
Page 147 and 148: Reduction of pigme
Page 149 and 150: though wheat gluten meal conta<stro
Page 151 and 152: BibliographyAas, G.H., Storebakken,
Page 153 and 154: Bjerkeng, B., Hatlen, B., Wathne, E
Page 155 and 156: Choubert, G., Cravedi, J., Laurenti
Page 157 and 158: Fauconneau, B., Andre, S., Chmaitil
Page 159 and 160: Johnston, I., Li, X., Vieira, V., N
Page 161 and 162: Li, M.H., Oberle, D.F., Lucas, P.M.
Page 163 and 164: Peter, C.M., Han, Y., Bolin
Page 165 and 166: Skonberg, D.I., Hardy, R.W., Barrow
Page 167: Ytrestoyl, T., Struksnæs, G., Kopp
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