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Research Project: Improving the Quality of Animal Hides, Reducing Environmental Impacts of Hide Production, and Developing Value-Added Products from Wool


2017 Annual Report

1: Enable new commercial methods to reduce or eliminate manure contamination of hides prior to hide removal, and one or more process models will be developed to estimate the expected costs for new technologies so enabled. 2: Enable new commercial methods for curing hides and skins and that reduce salt usage, and one or more models will be developed to estimate the expected costs for new technologies so enabled. 3: Enable new commercial methods to characterize hide quality in the raw state, and one or more models will be developed to estimate the expected costs for new technologies so enabled. 4: Enable new commercial products from Keratin extracted from wool.

The cleaning of bovine hides to remove manure balls and other organic contaminants will be enhanced by incorporating a combination of enzymes, glycerol, and sanitizing agents into the traditional cleansing solution ingredients. The efficiency of manure cleansing will be assessed by monitoring the bacterial count before and after the hide washings. Low salt hide preservation will be developed by using the combination of dehydrating agent, biocide, glycerol, and sanitizing agents with a fraction of the amount of salt used in traditional hide preservation. For improved efficiency and extended bovine hide preservation, the addition of various polyethylene glycol (PEG) fractions will be evaluated with the treatments of glycerol, biocides, and sanitizing agents. Nondestructive evaluation technology will be developed for the characterization of hide quality by incorporating airborne ultrasonic (AU) technology. The through transmission mode will be applied so that more useful information can be extracted from the AU scan, particularly for hides, which are covered by hair. The amplitudes of the transmitted airborne signals at every point on the hide surface were measured, color-coded, and mapped into an image file for each hide or leather. The correlation between AU data and physical properties of hides will be examined and statistical software will be used to establish the regression equation that enables one to predict the quality of hides using AU testing. Keratin will be extracted from coarse, low grade, unmarketable wool, by environmentally benign and economical methods, functionally modified by chemo-enzymatic methods, and applied to domestic wool, yarn, or fabric, to improve its properties. Conditions for chemical and enzymatic modification of wool will be optimized at the bench scale first, then scaled up. Intact wool will be modified chemo-enzymatically to add functional groups or functionalized keratin, and evaluated for improved properties, such as softness, comfort, resistance to shrinkage or improved water repellency. Promising research begun under a previous project, that demonstrated the ability of transglutaminase to catalyze the attachment of O-phosphorylethanolamine, potentially a flame retardant, to keratin and other proteins will be adapted for the surface derivatization of wool fabric, with the aim of imparting flame resistance. Economic assessment will be performed for all objectives every 12 months to evaluate the progress toward targets with adjustment along the way as necessary. After the process model is developed with equipment sizing and unit operations, capital and operating costs are then estimated using cost analysis software.

Progress Report
Progress was made on all objectives, all of which fall under NP 306 – Quality and Utilization of Agricultural Products, Component 2, Non-Food, Problem Statement 2B: To increase or protect the market demand for [or increase the value of] existing U.S.-produced non-food biobased products derived from agricultural products and byproducts, and ii. To enhance product quality, improve process efficiencies, and reduce processing risks for existing U.S. producers of non-food biobased products derived from agricultural products and byproducts. For Objective 1, project scientists developed novel presoaking formulations that demonstrated great effectiveness on softening and decontaminating manure balls. Environmental impacts (COD, bacterial count) have also been monitored at different stages of this process. To meet the commercial interest, the current research is being focused on developing spraying method instead of soaking process to clean and decontaminate the carcass at the same time. Our previously invented oxidative formulation is being used to develop the spray method of manure removal. The presence of manure balls on animal hides is a big problem to meat packers as it induces contamination of meat and currently available mechanical method of removing tightly bound manure balls often creates holes or damage to the hide which reduces the value of the hide and resulting leather products. So, understanding the importance of decontaminating carcass, two more projects are being carried out to develop nontoxic and environmentally friendly aqueous based solutions. Research data has revealed the effectiveness of the developed formulations in reducing bacterial growth, which will allow the meat packers to avoid cross contamination of pathogenic bacteria to produce safe meat. A cost analysis indicated a small increase in production cost due to the implementation of a new process in the meat packing plant, however, it could be reduced by lower losses due to contaminated meat, and higher prices for the hides. For Objective 2, project scientists developed formulations based on a 45% saturated brine solution in combination with bactericidal antiseptics to preserve bovine hides for more than 30 days in an environmentally friendly and economic way. An invention disclosure has been filed for these new formulations, which reduces salt consumption by more than 50% from the conventional curing process, where 95% saturated brine solution is being used. The invented technology offers better results than the traditional method on the basis of environmental impacts including reduction in total solid (TS), total dissolved solid (TDS), suspended solid (SS) and microbial population in the raw hide ensuring long time preservation. There are also significant reductions in Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) for spent soaking liquors generated by the alternative hide curing method in comparison to the traditional method. The physical and mechanical properties of the crust leather made from the alternatively cured hides using this invented method are comparable or even better in quality than the leather obtained from conventionally cured hide using 95% saturated brine solution. The cost analysis showed the developed preservation technique has the potential to be a techno-economically viable alternative for traditional high salt-based preservation. For Objective 3, project scientists are developing the method using airborne ultrasonics (AU) to characterize the properties of hides and further to predict the mechanical properties of leather. The nondestructive method is based on measuring the AU waves transmitted through the hide samples. We discovered the Time of Flight (TOF) distribution value at a particular TOF range yielded the best correlation with the AU test variables. This finding enables the AU testing to be more effective and time saving. Observations showed that the tensile strength, stiffness, elongation, and toughness of leather could be predicted by TOF and Amplitude distribution (AMP) measurements for hides. The significance of this finding is profound, especially as a quality control/quality assurance method for manufacturing and the potential for being a nondestructive testing method. A newly purchased AU system enables the hides to be mounted vertically to better simulate the manufacturing process. The new scanner can move in the xyz directions, resulting in more evenly scanning in multiple directions. The recent economic analysis still indicated the new AU testing system to be comparable to the current manual grading system. For Objective 4, project scientists evaluated keratin extracted from wool by environmentally benign methods, in the previous year, for suitability as a substrate for microbial transglutaminase (TG), an enzyme widely used in the food industry, that is effective at crosslinking and adding functionality to gelatin extracted from hides. Initial studies of TG mediated phosphate attachment, as a potential flame retardant, and 4-aminobenzoic acid (PABA) as a UV-protectant were made. Factors considered for the economic evaluation were the relative costs of chemical or enzymatic derivatization, including energy input and safety factors.

1. Preserving hide using less salt and low concentration of antiseptics. ARS researchers at Wyndmoor, Pennsylvania have developed a technique combining 45% saturated brine solution with a low concentration of antiseptic to preserve bovine hides for more than 30 days. This invention cuts salt usages by more than 50% from the traditional method. Observations showed the new formulation cured hides better and produced a better quality of leather. Due to the usage of less salt in the new method, a significant reduction in overall pollution has been monitored during hide processing, which will reduce the operating cost and protects environment. U.S. Hides, Skin and Leather Association showed enormous interest in stakeholder meeting in April, 2017 and is helping to push this technology to it’s member packing plants and hide producers.

2. High performance composite derived from tannery collagen wastes. ARS researchers at Wyndmoor, Pennsylvania collaborated with a foreign visiting scientist to develop natural proteinaceous materials from wastes generated in a tannery. This work combined gelatin and vegetable-tanned collagen fibers (VCF), using a non-toxic and naturally occurring compound, genipin, as cross-linking agent. The resultant composites showed high tensile strength, toughness, improved mechanical strength, and higher water resistance than the native gelatin film. Research results indicate that VCF can be useful to develop new green materials with better properties for the biomedical and packaging applications.

3. Hide decontamination treatment to improve beef safety and preserve hide quality. Bacterial cross-contamination from the haired outer surface of the hide to the meat during slaughter is recognized as a hygienic problem for commercial beef facilities. Treatments known to decontaminate the hide may erode the hide surface, decreasing its value to the leather industry. ARS researchers at Wyndmoor, Pennsylvania collaborating with Safe Foods, Inc., investigated the efficacy of a spray treatment with two antimicrobials on three regions (head, belly and butt) of the haired cattle hide. Both antimicrobial independently, effectively reduced bacterial concentrations on freshly procured cattle hides. Physical and mechanical tests revealed no damaging effects on crust leather produced from the treated hides with either formulation. The results from this study demonstrated that antimicrobial spray washing with the two antimicrobial solutions can effectively reduce harmful bacteria on cattle hides to the benefit of the beef and leather industries.

Review Publications
Brown, E.M., Pandya, K., Taylor, M.M., Liu, C. 2016. Comparison of methods for extraction of keratin from waste wool. Agricultural Sciences. 7:670-679. doi: 10.4236/as.2016.710063.
Liu, C., Latona, N.P., Brady, B. 2017. The prediction of leather mechanical properties from airborne ultrasonic testing of hides. Journal of American Leather Chemists Association. 112(3):94-101.
Marsico, R., Liu, C. 2017. A method for removing adobe-type manure from hides using an oxidizing agent. Journal of American Leather Chemists Association. 112(3):88-93.
Taylor, M.M., Bumanlag, L.P., Latona, N.P., Brown, E.M., Liu, C. 2017. Reaction of gelatin and chitosan with water soluble carbodiimides. Journal of American Leather Chemists Association. 112(2):52-58.