Importance of crosslinking and disulfide bridge reduction for the mechanical properties of rigid wheat gluten bioplastics compression molded with thiol and/or disulfide functionalized additives

Authors

  • Koen J. A. Jansens,

    Corresponding author
    1. Laboratory of Food Chemistry and Biochemistry, KU Leuven, Belgium
    2. Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Belgium
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  • Kevin Bruyninckx,

    1. Polymer Chemistry and Materials Division, Chemistry Department, KU Leuven, Belgium
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  • Lore Redant,

    1. Laboratory of Food Chemistry and Biochemistry, KU Leuven, Belgium
    2. Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Belgium
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  • Bert Lagrain,

    1. Laboratory of Food Chemistry and Biochemistry, KU Leuven, Belgium
    2. Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Belgium
    Current affiliation:
    1. Centre for Surface Chemistry and Catalysis, Belgium
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  • Kristof Brijs,

    1. Laboratory of Food Chemistry and Biochemistry, KU Leuven, Belgium
    2. Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Belgium
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  • Bart Goderis,

    1. Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Belgium
    2. Polymer Chemistry and Materials Division, Chemistry Department, KU Leuven, Belgium
    3. Leuven Material Research Centre (Leuven-MRC), KU Leuven
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  • Mario Smet,

    1. Polymer Chemistry and Materials Division, Chemistry Department, KU Leuven, Belgium
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  • Jan A. Delcour

    1. Laboratory of Food Chemistry and Biochemistry, KU Leuven, Belgium
    2. Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Belgium
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ABSTRACT

Thiol (SH) containing additives improve the mechanical properties of rigid, glassy gluten materials. However, the underlying molecular mechanism is still unclear. In particular, the importance of the preceding gluten-additive mixing conditions remains to be investigated. Here, different additives containing either only SH, only disulfide or both SH and disulfide functionalities were synthesized and their impact on the gluten network using different mixing conditions prior to subsequent molding were assessed. All SH containing additives decreased the gluten molecular weight (MW) during mixing to a degree depending on the conditions. Additives with only disulfide functionality did not significantly affect protein size during mixing irrespective of the conditions used. Only when mixing induced sufficient MW reduction did the strength and failure strain of rigid gluten materials increase. This shows that factors other than the degree of cross-linking affect the strength of rigid gluten materials. These results support our hypothesis that altered molecular conformations and improved molecular entanglements contribute to material strength. The extent to which such conformational changes occur may depend on the additive and the way of mixing. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41160.

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