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

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pigment bleach<strong>in</strong>g has been previously reported. Hydrogen peroxide (used as part of oxidationsystem based on the Fenton’s system at a concentration of 0.03%) reduced more than 30% <strong>and</strong>60% (measured as loss of absorbance) of total lute<strong>in</strong> <strong>and</strong> zeaxanth<strong>in</strong>, respectively <strong>in</strong> a fivem<strong>in</strong>utereaction at 25°C (Woodall et al., 1997). Through the course of corn steep<strong>in</strong>g progression,steepwater penetrates (through the tip cap) <strong>and</strong> disperses with<strong>in</strong> different structural compartmentof the gra<strong>in</strong> (i.e. germ <strong>and</strong> endosperm) by the action of capillary forces (Krochta et al., 1981).Hydrogen peroxide <strong>in</strong>cluded <strong>in</strong> steepwater <strong>in</strong> this trial, probably <strong>in</strong>duced an oxidation processwith<strong>in</strong> corn endosperm, thus bleach<strong>in</strong>g yellow carotenoids from the gluten fraction <strong>and</strong>consequently reduc<strong>in</strong>g the carotenoid recovery <strong>in</strong> corn gluten meal.<strong>Corn</strong> variety significantly affected the bleach<strong>in</strong>g of all-trans lute<strong>in</strong>, all-trans zeaxanth<strong>in</strong> <strong>and</strong>all-trans β-cryptoxanth<strong>in</strong> (Table 5.4). Dur<strong>in</strong>g steep<strong>in</strong>g, the rate of steepwater uptake is dependenton the permeability of the tip cap <strong>and</strong> aleurone layer (prote<strong>in</strong> layer cover<strong>in</strong>g endosperm <strong>in</strong> corngra<strong>in</strong>s) (Krochta et al., 1981). Structural differences attributed to lower hydrogen concentrations<strong>in</strong> response to fungal degradation have been determ<strong>in</strong>ed for different varieties of dried corn gra<strong>in</strong>(assessed us<strong>in</strong>g neutron tomography analysis) (Clevel<strong>and</strong> et al., 2008). Differences <strong>in</strong> <strong>in</strong>ternalstructure might change the degree of permeability <strong>in</strong> different varieties of corn kernels thusreduc<strong>in</strong>g contact between hydrogen peroxide <strong>and</strong> carotenoid molecules. Whether the two kernelsvarieties used <strong>in</strong> this trial presented different <strong>in</strong>ternal structure rema<strong>in</strong>s unknown <strong>and</strong> mightexpla<strong>in</strong> this result.Steepwater pH showed a significant effect on the bleach<strong>in</strong>g of all-trans zeaxanth<strong>in</strong> <strong>and</strong> alltransβ-cryptoxanth<strong>in</strong> (Table 5.4). Lower bleach<strong>in</strong>g rations of yellow carotenoids were observedunder alkal<strong>in</strong>e conditions for both types of kernels. Alkal<strong>in</strong>e hydrogen peroxide has beenreported as an effective bleach<strong>in</strong>g agent for the reduction of dark colour (expressed as total117
colour difference us<strong>in</strong>g a colorimeter) <strong>in</strong> wheat stillage (Abdel-Aal et al., 1996). However,sodium hydroxide utilized to modify steepwater alkal<strong>in</strong>ity <strong>in</strong> this trial most probably <strong>in</strong>creasedthe density of steep<strong>in</strong>g solution (Perry <strong>and</strong> Green, 1984) thus limit<strong>in</strong>g absorption of steepwaterby the kernel.Mass balance of starch obta<strong>in</strong>ed <strong>in</strong> this trial <strong>in</strong>dicated that 35% to 48% of the starchcontent <strong>in</strong> the <strong>in</strong>itial corn sample was not recovered (Table 5.5). These values are high comparedto those previously reported (6% to17% of starch loss) (Zehr et al., 1995; S<strong>in</strong>gh et al., 1997;Dowd, 2003). The occurrence of fermentation dur<strong>in</strong>g steep<strong>in</strong>g has been reported (Gawienowskiet al., 1999). Whether fermentation of starch occurred dur<strong>in</strong>g steep<strong>in</strong>g rema<strong>in</strong>s unknown <strong>and</strong>might expla<strong>in</strong> the high levels of unrecovered starch obta<strong>in</strong>ed <strong>in</strong> this study.On the other h<strong>and</strong>, values for prote<strong>in</strong> recovery were <strong>in</strong> general high, from 74% to 112%.This type of results has been previously associated to a low millability of corn kernels <strong>and</strong> tohigh recovery of starch <strong>in</strong> the gluten fraction (S<strong>in</strong>gh et al., 1997). Additionally, overestimationof prote<strong>in</strong> mass balance observed <strong>in</strong> this trial (e.i. values exceed<strong>in</strong>g 100%) can be attributed tosampl<strong>in</strong>g errors associated to the small quantity of sample used for the quantitative determ<strong>in</strong>ationof nitrogen (LECO, Dumas method).Mass balance for carotenoids obta<strong>in</strong>ed <strong>in</strong> this trial <strong>in</strong>dicated that a maximum of 65% <strong>and</strong>63% of total determ<strong>in</strong>ed yellow pigments conta<strong>in</strong>ed <strong>in</strong> the <strong>in</strong>itial sample were recovered <strong>in</strong> corngluten meals produced from varieties HiC7 <strong>and</strong> HiC23, respectively. This result <strong>in</strong>dicates thatabout 25% of yellow carotenoids are lost dur<strong>in</strong>g the wet mill<strong>in</strong>g process used <strong>in</strong> this trial evenunder acidic conditions (pH~2) <strong>and</strong> no hydrogen peroxide <strong>in</strong>clusion. No significant effect wasdeterm<strong>in</strong>ed for corn variety on mass balance of carotenoids <strong>in</strong> this study, suggest<strong>in</strong>g that118
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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
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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
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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 and 126: under acidic and a
Page 127: oxidation within t
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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