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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


2020 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 carried out further experiments on previously developed technology of removing mud/manure balls from the haired hide surface of cattle to make this technology commercially viable. Novel formulations and methods were developed to remove adobe type mud/manure balls from the cattle hide in 5 to 8 minutes, which ensured meat safety and by product quality. In FY 2020, three more mud/manure removing formulations were prepared using the similar (not same) chemicals, and side by side comparison was evaluated along with the previously developed formulation in terms of efficacy, cost, and post-application impacts. Under two separate Materials Transfer Research Agreements (MTRAs) with a meat packing company (No. 58-8072-9-015) and a chemicals producer (no. 58-8072-9-017), the ARS formulation has been tested at each company's location in an industrial setting and proved effective as expected. Based on industrial trials, a new MTRA is under preparation with Tyson Foods, Inc. where, a small issue of slipperiness of the formulation is expected to be solved through additional research. For Objective 2- In continuous efforts of developing hide preservation method with less environmental impact, project scientists investigated the preservation of hides with the treatment of chlorine dioxide. Chlorine dioxide is an antimicrobial gas and kills bacteria and spores to limit bacterial degradation and thus preserves hides from putrefaction. Instead of treating with neutral chlorine dioxide gas (ClO2), the hides were treated with an aqueous solution of sodium chlorite (NaClO2) because sodium chlorite was inexpensive and chlorite ions (ClO2-) penetrated deeper into the hides than the neutral chlorine dioxide. The chlorite ions trapped inside hides were then converted into chlorine dioxide when the hides were subsequently treated with dilute hydrochloric acid (HCl). In developing this two-steps process technology, concentration levels of sodium chlorite and HCl were optimized to obtain the best performance in terms of preserving hides. The research revealed that, this technology was effective in preserving bovine hides for more than 30 days while maintaining its quality. A full-scale evaluation of impacts on the leather produced from the preserved hides and environment are being carried out. From this research, a green method of hide preservation is expected to replace the traditional salt curing method, thereby protecting our natural resources. Moreover, the quality of hides was examined before and after being cured with the previously developed formulation using the airborne ultrasonic (AU) scanning method developed from Objective 3. For Objective 3- Project scientists continued to work on a nondestructive method using airborne ultrasonic (AU) scanning to characterize the hides and further to estimate the quality and physical properties of corresponding leather. The developed nondestructive AU method is based on measuring the ultrasound waves transmitted through the hide samples. Project scientists have discovered that the fullness and overall quality of leather could be estimated by the ultrasound quantities tested from corresponding hides. The results derived from this research are instrumental in establishing a quality control/quality assurance method for manufacturing. This research result has been submitted and published in a leather journal to stir stakeholders’ interests in adapting this new nondestructive evaluation method. Filed tests were done on the hides cured and preserved by a developed new method (developed through the research associated with objective 2) using less salt in a pilot plant tannery. Observations showed AU detects no detrimental impact on hides preserved by the new preservation method. For Objective 4- In order to improve the stability of wool products under sun exposure, project scientists developed a novel, environment-friendly method to treat wool. In this method, project scientists successfully introduced a relatively safe, ultraviolet-absorbing molecule to wool fabrics through an enzyme-mediated reaction. The reaction could create a strong binding between molecules and fabrics, so prolonged protection of fabrics was achieved. After treatment, the yellowing of wool fabrics was effectively slowed down, and the penetration of harmful ultraviolet light could be primarily blocked. The cost analysis of production was completed and it showed that the treatment cost is inexpensive. Project scientists also observed the slower degradation trend through scanning electron microscope images and mechanical property comparisons. The proposed treatment using bio-based enzymes may pave a new road for improving the photo-stability of wool products, which will further enhance their marketability.

1. Salt-loving bacteria can damage the animal hide. A strain of bacteria can survive and reproduce in salt or salt solution. A bacteria strain can grow on salt-cured animal hide or skin, creating red stains on the surface and eventually damaging the commercial value of cured hide used for making leather. ARS scientists in Wyndmoor, Pennsylvania, found that the aqueous solution of alkyltrimethylammonium bromide (ATMB) is effective in inhibiting the salt-loving bacterial strains that cause red heat/pink stain. Using ATMB in a small amount in hide curing solution will stop the growth of the bacteria and will prevent the losses of leather the industry caused by red heat or pink stains.

2. How to stop the yellowing of wool. Wool is a major textile fiber obtained from agricultural animals. However, the long-term exposure of wool to sunlight could cause yellowing and reduce its commercial value. ARS scientists at Wyndmoor, Pennsylvania, have developed a simple treatment by using a vitamin-like substance para-aminobenzoic acid (PABA), with high absorbance UV-light. The PABA and UV-light treated wool fabrics slows down yellowing rate caused by sunlight. An invention disclosure patent has been submitted and ARS scientists are seeking is an industrial partner to commercialize this new process to preserve wool.

Review Publications
Liu, C., Chen, N., Latona, N.P. 2019. The quality of leather estimated from airborne ultrasonic testing of hides. Journal of American Leather Chemists Association. 115(2):63-70.
Luo, L., Liu, J., Liu, C., Brown, E.M., Wang, F., Hu, Y., Tang, K. 2020. Thermogravimetric analysis and pyrolysis kinetics of tannery wastes in an inert atmosphere. Journal of American Leather Chemists Association. 115(4):123-131.
Sarker, M.I., Long, W., Liu, C. 2019. Limiting microbial activity as an alternative approach of bovine hide preservation, Part 1: Efficacy of Developed Formulations. Journal of American Leather Chemists Association. 114:271-278.
Sarker, M.I., Yosief, H.O., Liu, C., Latona, N.P. 2020. Limiting microbial activity as an alternative approach of bovine hide preservation Part II: impact of developed formulations on leather quality and the environment. Journal of American Leather Chemists Association. 115:54-62.
Hussain, S., Sarker, M.I., Yosief, H.O. 2020. Efficacy of alkyltrimethylammonium bromide for decontaminating salt-cured hides from the red heat causing moderatley halophilic bacteria. Letters in Applied Microbiology. 70:159-164.
Hussain, S.A., Xu, A., Sommers, C.H., Sarker, M.I. 2020. Draft genome sequence of red heat-causing halomonas eurihalina MS1, a moderately halophilic bacterium isolated from saline soil in Alicante, Spain. Microbiology Resource Announcements.