The effects of a series of organic acids--malic, citric and phytic acids--on the properties of edible gelatin films were studied by scientists.

The effects of a series of organic acids--malic, citric and phytic acids--on the properties of edible gelatin films were studied by scientists. An increase in the acid concentration of malic acid films can lead to a systematic decrease in their tensile strength and elastic modulus. Increases in tensile strength were found also for some concentrations of citric and phytic acids, 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 caused 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, compared with the control. Contact: Robert Kimmel, Department of Packaging Science, Clemson University, B-212 Poole Agricultural Center, Box 340370, Clemson, SC 29634. Phone: [phone]. Email: [e-mail].