DEVELOPMENT OF AGRICULTURALLY-DERIVED BIOPOLYMER COMPOSITES FOR NON-FOOD APPLICATIONS
Location: Bioproduct Chemistry and Engineering Research
Title: Cold Water Fish Gelatin Films: Effects of Cross-linking on Thermal, Mechanical, Barrier, and Biodegradation Properties
Submitted to: European Polymer Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 17, 2008
Publication Date: November 1, 2008
Citation: Chiou, B., Avena Bustillos, R.D., Bechtel, P.J., Jafri, H.H., Narayan, R.R., Imam, S.H., Glenn, G.M., Orts, W.J. 2008. Cold Water Fish Gelatin Films: Effects of Cross-linking on Thermal, Mechanical, Barrier, and Biodegradation Properties. European Polymer Journal. 44(11):3748-3753.
Interpretive Summary: Currently, mammalian gelatin comprises the majority of the gelatin market. We would like to find other sources of gelatin, such as those from fish, that can compete with mammalian gelatin. We extracted gelatin from Alaska pollock (Theragra chalcogramma) and Alaska pink salmon (Oncorhynchus gorbuscha) skins and cast them into films. These skins are by-products from the fishing industry in Alaska. It has been estimated that over a million tons of fish by-products are generated each year in Alaska. Some of these by-products are converted into fish meal and oil, but a large percentage are not utilized and are dumped back into the ocean. The by-products include substantial quantities of fish skin, which is a good source of gelatin. We examined the fish gelatins' water and oxygen barrier properties and compared them with those from mammalian gelatin films. All fish gelatin films had better barrier properties than mammalian gelatin films, which might make them competitve as coatings for food products, as wound dressings, and as packaging materials.
Gelatin was extracted from Alaska pollock (Theragra chalcogramma) and Alaska pink salmon (Oncorhynchus gorbuscha) skins and cast into films. The fish gelatin films’ tensile, thermal, water vapor permeability, oxygen permeability, and biodegradation properties were compared to those of bovine and porcine gelatin films. In addition, fish gelatin films were cross-linked with glutaraldehyde. Pollock and salmon gelatin films had comparable tensile properties, but had lower tensile strength and percent elongation than mammalian gelatin films. The lower strength and elongation might have been due to lower renaturation levels present in fish gelatin films. The addition of cross-linkers had little effect on tensile properties and melting temperatures of fish gelatin films. Pollock gelatin films had the lowest water vapor and oxygen permeability values, whereas mammalian gelatin films had the highest permeability values. Cross-linking resulted in lower water vapor permeability for salmon gelatin films and higher oxygen permeability for pollock gelatin films. However, all fish gelatin films had better water vapor and oxygen barrier properties than mammalian gelatin films. Also, fish gelatin films degraded faster than mammalian gelatin films.