Agricultural and Biological Systems Engineering, Department of
Department of Agricultural and Biological Systems Engineering: Faculty Publications
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Document Type
Article
Date of this Version
2003
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.
Comments
Published in Journal of Food Science: Food Engineering and Physical Properties 68:8 (2003), pp. 2516–2522. Copyright © 2003 Institute of Food Technologists. Used by permission.