73D-31 |
Characterization of SPI films plasticized with aqueous and crystalline sorbitol |
K. M. KIM1, C. L. Weller, M. A. Hanna, and A. Gennadios4. (1) Industrial Agricultural Products Center, University of Nebraska, 233 LW Chase Hall, Lincoln, NE 68583-0730, (2) Materials Science Research and Development, Banner Pharmacaps Inc., 4125 Premier Dr., High Point, NC 27265-8144 Soy protein films have poor moisture barrier properties due to the hydrophilic nature of the protein and the substantial amounts of hydrophilic plasticizer(s) used in film preparation. Use of glycerin as a plasticizer not only increases flexibility, but also results in very high water vapor permeability. This study showed moisture barrier properties improved by plasticizing with sorbitol. Our objective was to determine the plasticizing effect of mixture of aqueous and crystalline sorbitol on thephysical and barrier properties of soy protein isolate (SPI)film barrier properties. The plasticizing effect of the sorbitol mixture on selected properties (moisture content, water vapor permeability (WVP), color, tensile strength (TS), elongation (E), and soluble solids content) of cast SPI films was investigated. Aqueous sorbitol and crystalline sorbitol were added as the plasticizer in a ratio of 1:0, 0.25:0.75, 0.5:0.5, 0.75:0.25 or 0:1 (w/w of crystals:solution). To determine the relation of solubility and WVP of sorbitol-plasticized films, cumulative amounts of moisture content gained during adsorption and lost during desorption of films were compared between films plasticized with glycerin and between films plasticized with sorbitol. Mean values of TS for sorbitol-plasticized films were greater than TS mean values for glycerin-plasticized films. Mean values of WVP and E for sorbitol-plasticized films were less than WVP and E mean values for glycerin-plasticized films. A mean value of WVP across all sorbitol-plasticized films (3.74 x 10-6 g·m/m2·h·Pa) was lower than the mean value of WVP for glycerin-plasticized film (9.28 x 10-6 g·m/m2·h·Pa). SPI films plasticized with sorbitol were observed to greater solubility and less permeability to water than glycerin-plasticized films. Use of sorbitol as plasticizer improved moisture barrier properties of SPI films, however high solubility levels need to be lowered before potential packaging applications can be realized.
Session 73D, Food Packaging
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