Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2008
Publication Date: 7/1/2009
Citation: Hernandez, E., Taylor, M.M., Phillips, J.G., Marmer, W.N., Brown, E.M. 2009.PROPERTIES OF BIOPOLYMERS PRODUCED BY TRANSGLUTAMINASE TREATMENT OF WHEY PROTEIN ISOLATE AND GELATIN. Bioresource Technology. 100(14):3638-3643. Interpretive Summary: The processing of agricultural commodities often generates large volumes of low value coproducts; researchers are challenged to establish ways to add value to those materials. This research was undertaken to add value to agricultural waste proteins. Our prior research demonstrated that casein, whey, and gelatin, by-products from the dairy and the leather industries, could be enzymatically treated either individually or combined to form biopolymers with superior functional properties, such as gels with improved strength and high melting point. In this present study, we enzymatically combined whey with varying amounts of gelatin to form biopolymers that possess the unique properties of each individual protein. As in earlier experiments, we optimized reaction conditions for the primary protein, whey in this case, and then examined individually the properties of enzymatically modified whey and gelatin under these conditions, as well as their combined products. The physical properties of the whey biopolymers showed that the level of modification was enhanced by addition of even small amounts of the secondary protein, gelatin. These distinctive reactions have the potential of generating novel value-added products, e.g., superior films or coatings and, for the processing of hides, fillers to make the leather more uniform. An economic return could be realized with the utilization of by-products from these sustainable resources.
Technical Abstract: Byproduct utilization is an important consideration in the development of sustainable processes. Whey protein isolate (WPI), a byproduct of the cheese industry, and gelatin, a byproduct of the leather industry, were reacted individually and in blends with microbial transglutaminase (mTGase) at pH 7.5 and 45 deg C. When a WPI (10% w/w) solution was treated with mTGase (10 U/g) under reducing conditions, the viscosity increased four-fold and the storage modulus (G') from 0 to 300 Pa over 20 hours. Similar treatment of dilute gelatin solutions (0.5 to 3%) had little effect. Addition of gelatin to 10% WPI caused a synergistic increase in both viscosity and G', with the formation of gels at concentrations greater than 1.5% added gelatin. These results suggest that new biopolymers, with improved functionality, could be developed by mTGase treatment of protein blends containing small amounts of gelatin with the less expensive whey protein.