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Published on: July 11, 2012
Effect of 4-methylbenzoquinone concentration on its covalent conjugates with β-lactoglobulin: Structural and
Jinshun Ye1, Xiaotong Li1, Zhenzhao Weng1
1Engineering Research Center of Health Food Design & Nutrition Regulation, Dongguan Key Laboratory of Typical Food Precision Design, China National Light Industry Key Laboratory of Healthy Food Development and Nutrition Regulation, School of Life and Health Technology, Dongguan University of Technology, Dongguan 523808, China.
Abstract:
This study examined the effect of quinone concentration on covalent interaction between β-lactoglobulin (β-Lg) and 4-methylbenzoquinone (4MBQ). β-Lg-4MBQ-0.2, β-Lg-4MBQ-0.4, and β-Lg-4MBQ-0.8 were prepared at 1:2, 1:1, and 2:1 M ratio of 4MBQ to β-Lg thiols, respectively. β-Lg-4MBQ-0.8 had the highest polyphenol content (19.04 ± 0.17 mg/g) and the lowest free sulfhydryl (17.12 ± 0.18 μmol/g) and amino group (181.28 ± 5.37 μmol/g) contents. Compared to β-Lg, β-Lg-4MBQ conjugates showed reduced α-helix (0.82-1.26 %) and increased β-sheet (1.17-1.50 %) content. β-Lg-4MBQ-0.8 and β-Lg-4MBQ-0.4 exhibited higher surface hydrophobicity and emulsifying properties than β-Lg-4MBQ-0.2 and β-Lg. Antioxidant activity (DPPH and ABTS scavenging) followed: β-Lg-4MBQ-0.8 (46.75 ± 0.17 % and 50.97 ± 0.51 %) > β-Lg-4MBQ-0.4 (39.50 ± 0.27 % and 46.63 ± 0.59 %) > β-Lg-4MBQ-0.2 (33.35 ± 0.71 % and 43.00 ± 0.39 %) > β-Lg (31.50 ± 0.56 % and 36.25 ± 0.90 %). β-Carotene emulsions stabilized by β-Lg-4MBQ-0.4 exhibited the highest stability. These findings provide insights into developing antioxidant emulsifiers.
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