45D-11 |
Effects of a series of organic acids on the properties of edible gelatin films |
Y. T. KIM and R. M. KIMMEL. Dept. of Packaging Science, Clemson Univ., B-212 Poole Agricultural Ctr., Box 340370, Clemson, SC 29634-0370 The effects of a series of organic acids (malic, citric and phytic) on the properties of edible gelatin films prepared by the casting method based on 5% gelatin concentration were studied. The thermal and mechanical properties, morphology and water vapor permeability of these films, plasticized with 30% glycerol, were measured as a function of acid type and concentration. An increase of acid concentration in malic acid films resulted in a systematic decrease in tensile strength and elastic modulus. Increases in tensile strength were found also for some concentrations of citric and phytic acid, but these changes were not monotonic with acid concentration. The tensile strength of 1% malic acid film at twice that of the control film may be explained by ionic cross-linking. This cross-linking effect did not significantly affect the water vapor permeability of the malic and citric acid films. Films made with the more bulky phytic acid did however show a 50% increase in water vapor permeability. All the acids lead to a decrease in the DSC melting temperature of the films vs. the control. The results are consistent with a model based on acid molecular structure.
Session 45D, Food Packaging: General
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