Publications (8)8.84 Total impact
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Article: Application of transglutaminase to derivatize proteins: 1. Studies on soluble proteins and preliminary results on wool
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ABSTRACT: The use of enzymes in chemical processing is gaining favour due to the reduction of hazardous chemicals and because it is considered to be environmentally safe. The acyl transfer reaction between primary amines and glutamine residues in proteins is catalysed by the enzyme transglutaminase. The efficiency of microbial transglutaminase to attach functional amines and catalyse inter- and intra-molecular crosslinks was investigated using reduced carboxymethylated κ-casein, gelatin and wool. Model systems used in this research gave evidence of both cross-linking of the protein and covalent binding of the primary amine o-phosphorylethanolamine to the protein. These data agree with earlier publications that show transglutaminase catalyses the formation of covalent cross-links between the γ-carboxyamide group of glutamine and the ε-amino group of lysine and also the incorporation of primary amines into proteins. Preliminary analysis of treated wool indicated the covalent bonding of the functional amine to the protein. Our goal is to increase the value of wool by enzymatic addition of functional groups to the wool fibre. Published in 2004 for SCI by John Wiley & Sons, Ltd.Journal of the Science of Food and Agriculture 01/2005; 85(3):418 - 424. · 1.44 Impact Factor -
Article: Enzyme-catalyzed gel formation of gelatin and chitosan: potential for in situ applications.
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ABSTRACT: We compared the ability of two enzymes to catalyze the formation of gels from solutions of gelatin and chitosan. A microbial transglutaminase, currently under investigation for food applications, was observed to catalyze the formation of strong and permanent gels from gelatin solutions. Chitosan was not required for transglutaminase-catalyzed gel formation, although gel formation was faster, and the resulting gels were stronger if reactions were performed in the presence of this polysaccharide. Consistent with transglutaminase's ability to covalently crosslink proteins, we observed that the transglutaminase-catalyzed gelatin-chitosan gels lost the ability to undergo thermally reversible transitions (i.e. sol-gel transitions) characteristic of gelatin. Mushroom tyrosinase was also observed to catalyze gel formation for gelatin-chitosan blends. In contrast to transglutaminase, tyrosinase-catalyzed reactions did not lead to gel formation unless chitosan was present (i.e. chitosan is required for tyrosinase-catalyzed gel formation). Tyrosinase-catalyzed gelatin-chitosan gels were observed to be considerably weaker than transglutaminase-catalyzed gels. Tyrosinase-catalyzed gels were strengthened by cooling below gelatin's gel-point, which suggests that gelatin's ability to undergo a collagen-like coil-to-helix transition is unaffected by tyrosinase-catalyzed reactions. Further, tyrosinase-catalyzed gelatin-chitosan gels were transient as their strength (i.e. elastic modulus) peaked at about 5h after which the gels broke spontaneously over the course of 2 days. The strength of both transglutaminase-catalyzed and tyrosinase-catalyzed gels could be adjusted by altering the gelatin and chitosan compositions. Potential applications of these gels for in situ applications are discussed.Biomaterials 09/2003; 24(17):2831-41. · 7.40 Impact Factor -
Article: Effect of fillers prepared from enzymatically modified proteins on mechanical properties of leather.
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Article: Tanning effects of aluminum -genipin or -vegetable tannin combinations.
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Article: Powdered hide for research on tanning mechanisms.
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ABSTRACT: The conversion of animal hides into leather, the most valuable coproduct of the US meat industry, is a multistep process that has evolved more as art form than as science. A variety of dehairing and other hide preparation processes have been adopted without an understanding of how they affect the chemical and physical properties of the resulting leather. To develop a basis for designing or selecting effective sustainable tanning agents, a suitable model system must include an evaluation of the effects of pretanning steps. A protocol for the production of powdered hide is described. Moisture, ash, total protein as collagen, hydrothermal stability, collagenase resistance, proteoglycan content and molecular weight distribution were compared for powdered hide prepared from bated and not-bated hide. This research provides a basis for assessing the effects of different process steps, and represents an initial step in the development of well-characterized model systems for comparing research from different laboratories on tanning mechanisms. -
Article: Treatment of Low-quality Hides with Fillers Produced from Sustainable Resources: Effect on Properties of Leather.
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ABSTRACT: Prior research from this laboratory reported on the use of gelatin, alone or in combination with dairy byproducts (casein or whey), as a filler for leather. It was found that all these treatments had fully penetrated the blue stock, were not removed during washing, and had no significant effect on mechanical properties when compared to untreated controls, but did show improvements in the subjective evaluations over the controls with respect to handle, break, dye uptake, and fullness. In this present study we applied these treatments to hides that had grain properties that were characterized as being loose, more commonly known as having spring break, to see if a reduction in these undesirable properties could be realized. The treatments were applied to the butt, belly and neck areas of the hide, and these samples were subsequently retanned, colored and fatliquored (RCF). There were no significant differences between the untreated controls and treated samples with respect to mechanical properties. Importantly, however, it was determined from subjective evaluations, that those commonly inferior areas, such as belly and neck, showed improved cutting area when treated. At the same time, Scanning Electron Microscopy (SEM) was used to compare the blue stock of both poor quality hides and hides evaluated to be of better quality before and after RCF; distinct differences in fiber structure were observed, most dramatically in the belly area. Applying these treatments to low quality hides makes economic sense. Firstly, leathers are produced that present more quality cutting area, and, secondly, these renewable resources have the potential to replace petroleum feedstuffs that are increasingly becoming scarce as well as expensive. -
Article: Properties of biopolymers produced by transglutaminase treatment of whey protein isolate and gelatin
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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 °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 h. Similar treatment of dilute gelatin solutions (0.5–3%) 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.Bioresource Technology. -
Article: Whey protein isolate: a potential filler for the leather industry.
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ABSTRACT: The upgrading of leather that presents loose areas and poor grain break is one of the most value adding opportunities for a tanner. Typically, petroleum-based products are used to improve the final appearance and feel of crust leather. In this study, we demonstrate that blends composed of whey protein isolate (WPI), a byproduct of the cheese industry, and small amounts of gelatin, a byproduct of the leather industry, could be effectively used as filling agents for both shoe upper and upholstery leather. Wet blue leather from three different areas in the hide (butt, belly and neck) was treated with the WPI-gelatin blend, retanned, colored and fatliquored, and their subjective and mechanical properties evaluated. The effect of pretreatment of the wet blue samples with various concentrations of the enzyme microbial transglutaminase (mTGase) was also examined. It was found that the rate of uptake of the WPI-gelatin blend by upholstery wet blue increased four-fold when it was pretreated with a 2.5% mTGase solution. Conversely, this rate was decreased when shoe upper was pretreated with increasing amounts of mTGase. The subjective properties (e.g. handle, fullness, color and grain break) of both shoe upper and upholstery leather that were treated with the WPI-gelatin blend were significantly improved over the controls. Importantly, the grain break of the belly area of samples that were pretreated with enzyme (both upholstery and shoe upper) was remarkably improved. Hence, fillers mainly composed by the less expensive WPI were demonstrated to be effective filling agents for both upholstery and shoe upper leather.
