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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


2019 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 under NP 306 – Quality and Utilization of Agricultural Products, Component 2, Non-Food, Problem Statement 2A: Maintain/increase/enhance non-food product (fiber including hides) quality by developing new or improved postharvest technologies/process efficiencies and reducing processing risk. For Objective 1, project scientists previously developed and tested the effectiveness of spray hide washing formulations consisting of natural compounds such as cinnamaldehyde and lactic acid to ensure meat safety and byproduct quality. Treatment with the novel formulation significantly reduced the bacterial concentration on the haired surface of bovine hides in 1 to 5 minutes. In FY 2019, the application of cinnamaldehyde/lactic acid formulation was evaluated to ensure there was no negative impact on the leather made from the treated hides. In a separate experiment, the scientists also evaluated two commercially available antimicrobials alkyltrimethylammonium-bromide (ATMB) and chlorhexidine-digluconate (CDG), which are considered non-toxic chemicals for their use in human consumption, for their ability to reduce the bacteria from the haired surface of bovine hides. These two antimicrobials, ATMB and CDG, showed promising results in significantly reducing the bacteria on inoculated fresh bovine hides. These carcass/hide decontamination formulations could be used for improving meat safety and byproduct quality. Significant progress was made on removing mud/manure balls from the hide surface. The developed formulation and application protocol was experimentally proven to remove adobe type mud/manure balls from the haired surface of hides within 5 to 8 minutes. Both spraying and soaking methods for dispensing the formulation on the hide surface can be adopted. Two industry partners have been identified in establishing a Material Transfer Research Agreement (MTRA) with ARS. For Objective 2, in a continuous effort to reduce salt usage in bovine hide preservation, project scientists reduced the saturated brine solution to 35% incorporated with a low concentration (0.25%) of selected fungicide/bactericide to preserve bovine hides for more than 30 days. This progress represents a total of 15% and 65% reduction of salt usage compared to our previously developed and the traditional method of hide preservation, respectively. In FY 2019, the adoptability of this alternative hide curing system was assessed by monitoring the leather processing effluents. Total dissolved solid (TDS), chloride content (Cl-), total solids (TS), total aerobic bacterial counts, bio-chemical oxygen demand (BOD) and chemical oxygen demand (COD) tests were performed on the soaking liquor of preserved hides to evaluate the environmental impact of the alternative hide curing process. To check the impact of the newly developed hide curing formulation on the final leather product, leather produced from the treated hide samples were evaluated for grain pattern analysis, microscopic screening, mechanical properties, and organoleptic testing. In this study, research results suggest that the developed technique has the potential to be a viable alternative for traditional high salt-based curing. For Objective 3, project scientists established the relationship between the quality of bovine hides and airborne ultrasonic (AU) quantities. Hides were scanned using the AU system per the experimental procedure previously established. The AU test system consisted of two ultrasonic transducers, a transmitter and a receiver with a preamplifier mounted on a computer-controlled 3-D scanner that allowed the transducer/receiver array to be moved over the entire surface of the hide sample. We correlated the quality characteristics of the resultant leather, such as handle, softness, and grain pattern with the physical quantities such as time of flight and amplitude obtained from AU testing. Project scientists also established the AU test method for wool fabrics and investigated the effects of UV protectant treatments on the AU physical quantities on the resultant wool fabrics. For Objective 4, project scientists have identified a suitable solvent capable of dissolving wool fibers into keratin solutions. Aminobenzoic acid, UV protectant, was added to a keratin solution with microbial transglutaminase (TG), a natural catalyst, enabling the UV resistant functional group to be bonded with the keratin molecules. The wool fabric was treated with the resultant keratin solution and the UV resistance was evaluated using a Fadeometer. Dissolution capacity was scaled up from 100 mL to 500mL. To predict the environmental impact of this process, we used the tests developed under hide preservation (Objective 2) to measure the quality of the water effluent. In addition, protein characterization for the extracted keratin protein was performed. Thermal stability and degradation kinetics of collagen fiber. During the processing of animal hides into leather, a large amount of collagen fibrous waste is generated. Various leather fiber reinforced/filled polymer composites have been developed to convert collagen waste into valuable products. Because collagen fibers degrade while heating and reduce their physical properties, it is very important to improve the thermal stability of collagen fibers and have an in-depth understanding of the thermal decomposition kinetics and mechanism. In a collaborative research with a foreign visiting scientist for the thermal stability and degradation kinetics of collagen fiber, we have demonstrated that both the thermal stability and decomposition kinetics are greatly influenced by the incorporation of calcium carbonate. This study provides a useful method for fabricating high-performance polymer composites based on collagen fibers. The research results were presented at the 2019 American Leather Chemists Association Annual Meeting and stirred a great interest in the utilization of collagen waste.

1. Development of new washing solution to decontaminate cattle hides for meat safety and quality. Decontamination of cattle carcass prior to hide removal is important to avoid pathogen transfer from hide-haired surface to underlying meat during meat processing, which can pose a threat to public safety. ARS researchers at Wyndmoor, Pennsylvania, have developed a formulation using non/less toxic aqueous soluble chemicals which can be applied by spraying on the surface of a cattle hide to significantly reduce microbial contamination, including pathogens in a short time of 1-5 minutes. Also a soaking method has been developed in FY19 using the recently developed mud/manure removing formulation to clean the external debris from the hide surface in 5 minutes, which also reduces the bacterial contamination therefore, the inventive formulation can potentially be used in both meat and hide processing facilities. A patent application has been submitted to U.S. Patent Office and two Material Transfer Research Agreements (MTRAs) have been established with two commercial companies.

2. Limiting microbial activity as an alternative approach of cattle hide preservation. Traditional salt curing for preservation of bovine hides generates significant effluent pollution that is an environmental issue for the industry. ARS researchers at Wyndmoor, Pennsylvania, have recently developed a hide curing formulation containing a low concentration of bactericide that is more effective in limiting microbial growth and reduces salt usage by 65% from traditional processes. In addition, the effluent pollution load was reduced by more than 50% and leather produced was comparable to that made from traditionally cured hides. A Cooperative Research and Development Agreement (CRADA) is being established with a hide processor.

Review Publications
Huang, J., Liu, J., Tang, K., Yang, P., Fan, X., Wang, F., Du, J., Liu, C. 2018. Effect of cyclic stress while being dried on the mechanical properties and thermostability of leathers. Journal of American Leather Chemists Association. 113(11):318-325.
Long III, W., Sarker, M.I., Liu, C. 2018. Cinnamayldehyde/lactic acid spray wash treatment for meat safety and byproduct quality assurance. Journal of Food Science and Technology. 6(6):280-289.
Long III, W., Sarker, M.I., Annous, B.A., Paoli, G. 2019. Decontamination of bovine hide surfaces for enhancing food safety: Use of alkyltrimethylammonium bromide and chlorhexidine digluconate. LWT - Food Science and Technology. 109:255-260.
Liu, J., Brown, E.M., Uknalis, J., Liu, C., Luo, L., Tang, K. 2018. Thermal stability and degradation kinetics of vegetable-tanned collagen fiber with in-situ precipitated calcium carbonate. Journal of American Leather Chemists Association. 113(11):358-370.
Sarker, M.I., Long III, W., Piazza, G.J., Latona, N.P., Liu, C. 2018. Preservation of bovine hide using less salt with low concentration of antiseptic, part II: Impact of developed formulations on leather quality And environment. Journal of American Leather Chemists Association. 113:335-342.
Wyatt, V.T., Boakye, P.G., Jones, K.C., Latona, N.P., Liu, C., Strahan, G.D., Zhang, J., Besong, S.A., Lumor, S.E. 2019. Synthesis of absorbent polymer films made from fatty acid methyl esters, glycerol, and glutaric acid: thermal, mechanical, and porosity analysis. Journal of Applied Polymer Science. 1-15.