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Gelatin was chemically modified by crosslinking samples with one of a number of bifunctional reagents as was done earlier in a processing technique used to improve mechanical properties through chain orientation. The effects of this crosslinking on the biodegradability of the resulting films were evaluated in the laboratory by exposing them to lake and river waters for 10 days with or without inoculation with periphyton organisms. Biodegradabilities were assessed by weight losses of the films and by measurements of dehydrogenase activity of biomasses taken from their surfaces. The extent of biodegradation depended on the type of crosslinking agent and the presence or absence of the periphyton. The gelatin films crosslinked with formaldehyde, glyoxal, or glutaraldehyde were the slowest to biodegrade; complete degradation required 8 -10 days. In contrast, the most biodegradable was the gelatin crosslinked with hexamethylene diisocyanate, which required only 3-4 days. The uncrosslinked gelatin and the gelatin crosslinked with butadiene diepoxide and diepoxyoctane were intermediate, degrading in 5-7 days. The dehydrogenase activity paralleled the weight losses but rapidly decreased when the amount of gelatin remaining was small.

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Gelatin films that had been chemically modified (crosslinked with formaldehyde, glyoxal, glutaraldehyde, hexamethylene diisocyanate, butadiene diepoxide, or diepoxyoctane) were tested for their biodegradability by soil burial testing in a laboratory environment under temperature and humidity control. The relationship between weight loss and time of biodegradation showed a linear behavior for all the samples, but the rate of biodegradation showed a dependence on the type of crosslinking agent. The most stable films were those crosslinked with aldehydes, and these biodegraded by the 10th day. The samples crosslinked with hexamethylene diisocyanate and diepoxides completely biodegraded by the fourth and sixth days, respectively. It was shown that the rate of biodegradation depended on the density of crosslinking, which was calculated by a modified Flory–Rehner equation. The biodegraded samples showed considerable changes in the fingerprint region of FTIR spectra, and, thus, these spectra could be used for evaluation of the soil burial biodegradation of chemically modified gelatin samples. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1341–1347, 2000

Abstract:The emulsifying properties of proteins have been well studied as they are important for the preparation of creams, mayonnaises and other oil/fatcontaining foodstuffs. The emulsifying action of a protein is not always sulXcient to obtain stable emulsions of good quality. The use of chemical stabilisers in the food industry is not desirable. One of the best ways to improve the quality of emulsions and to produce emulsions with high nutritive value is to use proteinpolysaccharide complexes as emulsifiers. Varying the protein-polysaccharide ratio in the complex, and also the kind of the polymers, would vary the quality and the nutritional value of the foodstuff. Four non-conventional protein preparations were tested as emulsifiers and their emulsifying properties were improved by the addition of pectin. This makes it possible to create new foodstuffs with low oil content and high nutritional value.