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Water solubility and mechanical properties of heat cured whey protein isolate-based edible films: A comparison to commercial collagen and natural casings |
S. AMIN1, B. R. Harte2, and Z. Ustunol1. (1) Dept. of Food Science & Human Nutrition, Michigan State Univ., 2100 S. Anthony Hall, East Lansing, MI 48824-1225, (2) School of Packaging, Michigan State Univ., 130 Packaging Bldg., East Lansing, MI 48824-1223 Currently collagen films are the only edible alternative to natural casings available to the food industry. The surplus of whey and its functional properties make it an attractive choice for the production of edible films. Heat curing improves the mechanical properties of these protein-based films. The purpose of this study was to determine the effect of heat-curing conditions on mechanical properties and water solubility of whey protein isolate-based films (WPI) with different plasticizer contents and compare these to collagen and natural casings. WPI (5% w/v) with three levels of glycerol (Gly; 2.7, 3.3, 3.5% w/v) and candelilla wax (CW; 0.8% w/v) were prepared and heat-cured at 80°C, 90°C and 100°C for 12, 24, 48 and 72h. Tensile strength (TS), elongation at break (%E) and wet strength (WS) were determined using standard ASTM procedures and compared to collagen and natural casings. Water solubility (23°C, 24h) of WPI, collagen and natural casings were also determined. Heat curing produced films with higher TS than uncured control films. Increasing the time and temperature of heat curing increased the TS of WPI. As curing temperature and time increased and plasticizer content decreased %E for the WPI decreased. The WS of the heat-cured films was greater than the uncured films. Collagen and natural casings had higher WS than the heat cured films. Water solubility of WPI decreased with increased curing time and decreasing plasticizer content. All WPI, heat cure and uncured films, along with collagen had water solubility higher then natural casings. Increasing the time and temperature of heat curing as well as decreasing the plasticizer content of WPI increased the TS and WS. Increasing heat cure time can decrease the %E and water solubility of WPI. Heat curing will produce WPI with TS, %E and water solubility similar to collagen
Session 26, Dairy Foods: General developments in dairy technology
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