100B-27 |
Influence of sorghum wax, glycerin and sorbitol on SPI films |
K. M. KIM1, C. L. Weller1, M. A. Hanna1, and D. B. Marx2. (1) Industrial Agricultural Products Center, University of Nebraska, 208 LW Chase Hall, Lincoln, NE 68583-0730, (2) Department of Biometry, University of Nebraska, 103 Miller Hall, Lincoln, NE 68583-0712 One of the main limitations of wax-soy protein isolate (SPI) composite films is their difficulty to prepare. Additional processing such as heating and homogenizing is required. Most previous experiments have been performed with refined lipid materials. Naturally-occurring wax containing polar and hydrophilic parts, may be more miscible in an aqueous film-forming solution. Glycerin, as a plasticizer, increases flexibility of edible film and sorbitol plasticizes SPI film effectively in terms of tensile strength (TS) and water vapor permeability (WVP). To use wax-SPI composite films containing effective plasticizers, interactions between wax and plasticizers need to be understood. Our objectives were to gain a better understanding of sorghum wax, glycerin and sorbitol on the properties of SPI films. A response surface experiment was designed to identify the relationships between three independent variables, content of sorghum wax (%, w/w), sorbitol (g/5g protein) and glycerin (g/5g protein) and measured film properties such as WVP, TS, elongation at break (E), total color difference and total soluble matter (TSM). All independent variables significantly affected (P<0.05) SPI film WVP, TS, E, total color difference and TSM. Sorghum wax concentration decreased WVP and E as sorbitol content increased WVP and TS in the composite films. Sorbitol had critical point of addition level for E and TSM of SPI film, however, sorbitol did not improve film properties. This result could have been due to incompatibility of the non-wax components of the ethanol-extracted sorghum wax with plasticizers. This study provides information on plasticizers and sorghum wax extracted by ethanol. It indicates that sorbitol has limitations as a good plasticizer. Sorghum wax extracted by ethanol contains non-wax component and is not compatible with glycerin, and especially sorbitol.
Session 100B, Food Packaging
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