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

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to Christiansen et al. (1995). H° ab is (as the relati<strong>on</strong>ship between the yellowness <str<strong>on</strong>g>and</str<strong>on</strong>g> redness) as:(7) H° ab =tan -1 b*/a*. Where 0° (H° ab = 0) represents a red hue <str<strong>on</strong>g>and</str<strong>on</strong>g> 90° (H° ab = 90) represents ayellow hue. The C* expresses saturati<strong>on</strong> <str<strong>on</strong>g>and</str<strong>on</strong>g> clarity of a colour. A high C* value represents ahigh saturati<strong>on</strong> of colour. It was calculated as: (8) C* = (a* 2 + b* 2 ) 1/2 .Lipoxygenase activity determ<str<strong>on</strong>g>in</str<strong>on</strong>g>ati<strong>on</strong>. Lipoxygenase activity <str<strong>on</strong>g>in</str<strong>on</strong>g> WSFF, heat treated WSFF<str<strong>on</strong>g>and</str<strong>on</strong>g> CGM, was determ<str<strong>on</strong>g>in</str<strong>on</strong>g>ed accord<str<strong>on</strong>g>in</str<strong>on</strong>g>g to Gӧkmen et al. (2007) with some modificati<strong>on</strong>s. Enzymeextracti<strong>on</strong> was carried out by homogeniz<str<strong>on</strong>g>in</str<strong>on</strong>g>g 5 g of sample with sodium phosphate (25 mL)buffer (pH 6.5) at 4°C us<str<strong>on</strong>g>in</str<strong>on</strong>g>g a magnetic stirrer for 30 m<str<strong>on</strong>g>in</str<strong>on</strong>g>. The homogenate was centrifuged at15,000 x g for 15 m<str<strong>on</strong>g>in</str<strong>on</strong>g> at 4°C. The supernatant c<strong>on</strong>ta<str<strong>on</strong>g>in</str<strong>on</strong>g><str<strong>on</strong>g>in</str<strong>on</strong>g>g lipoxygenase was kept as a crudeenzyme extract. The total prote<str<strong>on</strong>g>in</str<strong>on</strong>g> c<strong>on</strong>tent of the enzyme extract was determ<str<strong>on</strong>g>in</str<strong>on</strong>g>ed us<str<strong>on</strong>g>in</str<strong>on</strong>g>g the Sigmadiagnostics kit for micro prote<str<strong>on</strong>g>in</str<strong>on</strong>g> determ<str<strong>on</strong>g>in</str<strong>on</strong>g>ati<strong>on</strong> (Sigma Oakville, ON, Canada).The substrate soluti<strong>on</strong> was obta<str<strong>on</strong>g>in</str<strong>on</strong>g>ed by comb<str<strong>on</strong>g>in</str<strong>on</strong>g><str<strong>on</strong>g>in</str<strong>on</strong>g>g pure l<str<strong>on</strong>g>in</str<strong>on</strong>g>oleic acid (157.2 µL), Tween20 (157.2 µL) <str<strong>on</strong>g>and</str<strong>on</strong>g> nano-pure water (10 mL). 1 N NaOH (1mL) was added <str<strong>on</strong>g>and</str<strong>on</strong>g> the mixture wasdiluted to 200 mL with M/15 sodium phosphate buffer (pH 6.0).Spectrophotometric lipoxygenase activity determ<str<strong>on</strong>g>in</str<strong>on</strong>g>ati<strong>on</strong> was c<strong>on</strong>ducted by add<str<strong>on</strong>g>in</str<strong>on</strong>g>g 29.9mL of substrate soluti<strong>on</strong> <str<strong>on</strong>g>in</str<strong>on</strong>g> a flask placed <str<strong>on</strong>g>in</str<strong>on</strong>g> a water bath set up at 30 °C. Gently aerati<strong>on</strong> waspassed through the soluti<strong>on</strong> for 2 m<str<strong>on</strong>g>in</str<strong>on</strong>g>. The reacti<strong>on</strong> was <str<strong>on</strong>g>in</str<strong>on</strong>g>itiated by mix<str<strong>on</strong>g>in</str<strong>on</strong>g>g the crude enzymeextract (0.1 mL) <str<strong>on</strong>g>and</str<strong>on</strong>g> the substrate soluti<strong>on</strong>. Aliquots (1 mL) were transferred <str<strong>on</strong>g>in</str<strong>on</strong>g>to labeled testtubes c<strong>on</strong>ta<str<strong>on</strong>g>in</str<strong>on</strong>g><str<strong>on</strong>g>in</str<strong>on</strong>g>g 4 mL of 0.1 Normal NaOH soluti<strong>on</strong> at 0.5, 1.0, 1.5, 2.0, 2.5 <str<strong>on</strong>g>and</str<strong>on</strong>g> 3.0 m<str<strong>on</strong>g>in</str<strong>on</strong>g> ofreacti<strong>on</strong> time. NaOH soluti<strong>on</strong> stops the enzymatic reacti<strong>on</strong> <str<strong>on</strong>g>and</str<strong>on</strong>g> c<strong>on</strong>trol optical <str<strong>on</strong>g>in</str<strong>on</strong>g>terference <str<strong>on</strong>g>in</str<strong>on</strong>g> thesoluti<strong>on</strong> before absorbance measur<str<strong>on</strong>g>in</str<strong>on</strong>g>g. Hydroperoxide formati<strong>on</strong> was followed us<str<strong>on</strong>g>in</str<strong>on</strong>g>g a VarianInc., spectrophotometer (Palo Alto, CA, USA) as <str<strong>on</strong>g>in</str<strong>on</strong>g>crease <str<strong>on</strong>g>in</str<strong>on</strong>g> absorbance at 234 nm. A blank41

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