Molecular Dynamics of Soy-Protein Isolate Films Plasticized by Water and Glycerol

Authors

  • S.-G. Choi,

    1. Authors Choi and Kerr are with the Univ. of Georgia, Dept. of Food Science and Technology, Athens, GA 30602. Authors Kim, Hanna, and Weller are with the Univ. of Nebraska, Lincoln, Neb. Direct inquiries to author Kerr (E-mail wlkerr@arches.uga.edu).
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  • K.M. Kim,

    1. Authors Choi and Kerr are with the Univ. of Georgia, Dept. of Food Science and Technology, Athens, GA 30602. Authors Kim, Hanna, and Weller are with the Univ. of Nebraska, Lincoln, Neb. Direct inquiries to author Kerr (E-mail wlkerr@arches.uga.edu).
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  • M.A. Hanna,

    1. Authors Choi and Kerr are with the Univ. of Georgia, Dept. of Food Science and Technology, Athens, GA 30602. Authors Kim, Hanna, and Weller are with the Univ. of Nebraska, Lincoln, Neb. Direct inquiries to author Kerr (E-mail wlkerr@arches.uga.edu).
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  • C.L. Weller,

    1. Authors Choi and Kerr are with the Univ. of Georgia, Dept. of Food Science and Technology, Athens, GA 30602. Authors Kim, Hanna, and Weller are with the Univ. of Nebraska, Lincoln, Neb. Direct inquiries to author Kerr (E-mail wlkerr@arches.uga.edu).
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  • W.L. Kerr

    1. Authors Choi and Kerr are with the Univ. of Georgia, Dept. of Food Science and Technology, Athens, GA 30602. Authors Kim, Hanna, and Weller are with the Univ. of Nebraska, Lincoln, Neb. Direct inquiries to author Kerr (E-mail wlkerr@arches.uga.edu).
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Abstract

ABSTRACT: The effects of water and glycerol on the molecular mobility of a soy-protein isolate (SPI)-based film were investigated using 1H nuclear magnetic resonance (NMR). SPI-films were prepared with different glycerol contents and equilibrated to various levels of water activity (aw). The distributed transverse relaxation of film samples showed 2 distinct components: a solid-like fraction (T2s*) and a liquid-like fraction (T2m*). The peak T2s* values of films with lower glycerol concentration were more sensitive to variation in aw. As aw increased, the change of solid-like to liquid-like fraction was observed in higher glycerol films. As glycerol content increased, a minimum longitudinal relaxation time (T1) occurred at lower aw. Our results suggest that NMR techniques can be used to quantify the plasticizing effects on biopolymer films.

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