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Histological Analysis of the Skin Dermal Components in Bovine Hides Stored under Different Conditions 
by S. Montelli, L. Corain, B. Cozzi and A. Peruffo
Volume: 110      Number: 2     Page: 54-61     Year: 2015
 
 
Waterborne Dimethylolpropionic Acid-diisocyanate Adducts with Alkali-deblockable Isocyanate Groups as Pretanning Agent for Chrome Tanning 
by Jie Liu, Zhou Xu, Yi Chen and Haojun Fan
Volume: 110      Number: 2     Page: 43-53     Year: 2015
 
 
Determination of Hydrolytic Enzyme Capabilities of Halophilic Archaea Isolated from Hides and Skins and Their Phenotypic and Phylogenetic Identification 
by S.T. Bilgi, B. Mericli Ya and Ismail Karaboz
Volume: 110      Number: 2     Page: 33-42     Year: 2015
 
 
Biobased Films Prepared from Collagen Solutions Derived from Un-tanned Hides 
by C.K. Liu, N. Latona, M. Taylor and M. Aldema-Ramos
Volume: 110      Number: 2     Page: 25-32     Year: 2015
 
 
Rapid Fiber Opening Process for Skins: An Approach for Fail-Safe Chemical-Free Process 
by J. Durga, A. Ranjithkumar, R. Ramesh, C. Rose and C. Muralidharan
Volume: 110      Number: 1     Page: 7-12     Year: 2015
Conventional beam house operations adopted by the global tanning industry are coming under the close scrutiny of the environmentalists on account of the possible adverse effect on human health and environment. Lime, which is used to the tune of about 10% on the weight of the raw hides and skins, in re-liming stage contribute to generation of large quantities of sludge, the disposal of which is a serious concern. Also the process duration to achieve the required fiber opening in the re-liming process is very long, ranging from 24-72 hrs for different substrates and end products. Enzyme based beam house processes are being advocated to overcome the problems associated with the conventional processes. However, enzyme based methods need greater control over process parameters to achieve satisfactory results in leather processing and avoid damage to the pelt. To overcome the problems associated with the conventional re-liming process, an attempt has been made in the present investigation to utilize cocktail of carbohydrases for fiber opening of hides and skins. Fiber opening at optimized concentration of the above enzyme has been studied for its efficiency on goatskins. A process using optimum quantity of enzyme led to fiber opening in 30 minutes. The efficacy of enzyme on rapid fiber opening of dehaired skin was studied at different experimental conditions of pH, time and enzyme concentration. The performance of the enzyme in the given experimental conditions was assessed by quantifying the removal of carbohydrate and proteoglycan and examining the fiber opening by scanning electron microscopic studies. Effect of enzyme on the final quality of the leather was evaluated by changes in chemical characteristics, physical properties and visual examination.
 
 
Powdered Hide Model for Vegetable Tanning II: Hydrolyzable Tanni 
by E. Brown, M. Taylor ad L. Bumanlag
Volume: 110      Number: 1     Page: 19-22     Year: 2015
Vegetable tannages employ both condensed and hydrolyzable tannins. As part of our exploration of tanning mechanisms, we reported previously on interactions of the condensed tannin, quebracho, with powdered hide. In this study, the interactions of chestnut extract, a hydrolyzable tannin, with powdered hide samples are reported and compared with those of the condensed tannin. Hydrothermal stability of powdered hide treated with the hydrolyzable tannin reached a maximum of 75 C at a 40% offer, compared with 84 C for a similar offer of condensed tannin. The hydrolyzable tannin was much more effective at improving collagenase resistance, with nearly complete protection at <10% offer.
 
 
Color Forming Property of Derivative and Modification Products of Natural Iridoids with Methylamine 
by Xue Shao, Keyi Ding ad Jun Liu
Volume: 110      Number: 1     Page: 1-6     Year: 2015
Derivatives and modified products of five natural iridoids(geniposide, gentiopicroside, swertiamarin, loganin and morroniside) were obtained by derivatization or modification. Compounds before and after derivatization or modification were adopted to react with methylamine to investigate their color-forming property. The relationship between the color of the pigments and the structure was analyzed using ultravioletvisible(UV-vis) spectroscopy. The results indicated that: (1) when the backbone of the iridoids was the same, the position of the modified substituent groups had the greatest effect on the color of the pigments formed. For example, methygentiopicroside aglycone and methylswertimarin aglycone have a similar skeleton structure, differing only at positions C-5 and C-6, and the pigments obtained from their reaction with methylamine were also similar i.e. bright yellow. However, geniposidic acid aglycone and genipin, which also have a similar skeleton structure, differing only in the substituent at position C-4, produce pigments of different color upon reaction with methylamine, one being dark blue and the other purple red. (2) In different buffer systems, i.e., phosphate buffered saline (PBS, pH=8.0) and acetate buffer (ACE,pH=5.0), the same iridoid formed pigments with different colors. (3) After the - conjugation of benzoyl was introduced to the skeleton of loganin, genipin and morronin as a substituent group, the characteristic absorption wavelength of pigments changed. Taking loganin as an example, the characteristic absorption wavelength of pigments changed from 430 nm and 650, to 465 nm and 670 nm when reacted in PBS, and from 560 nm to 610 nm when reacted in ACE. The reason might be that the conjugation system became longer and the molecular structure became more stable.
 
 
Utilization of Agricultural By-products to Partially Replace Gelatin in Preparation of Products for Leather 
by M.Taylor, L. Bumanlag J. Lee, N. Latona, E. Brown and C.-K Liu
Volume: 110      Number: 1     Page: 13-18     Year: 2015
When polyphenolic-modified gelatin-products were used as fillers, improvements were seen in the subjective properties of the leather. When the treated samples were compared to control samples, there were no significant changes in mechanical properties. At the present time, gelatin is in short supply, costs are increasing, and there is an urgent need to find a substitute that could be combined with the gelatin, thereby, partially replacing and reducing the amount of gelatin required, with the goal that the new products would retain the desired characteristics of gelatin products. We have evaluated the potential of producing biopolymers from the reaction of polyphenols with gelatin in combination with other proteins (e.g. whey) or with carbohydrates (e.g. chitosan and pectin). Several researchers have recently demonstrated the feasibility of these reactions. These combinations would take advantage of the distinctive properties of both species and at the same time create products with improved functional properties. Recently, the preparation of polyphenolic-modified gelatin/ whey biopolymer products was investigated, and the results of product characterization using physicochemical analyses indicated optimal products that could be used as fillers. In this continuing study, these products were applied to wet white, that was then finished, and subjective and mechanical properties were evaluated. At the same time a method was developed to determine the rate of uptake of the product. Results of the studies will be presented. These findings could further add to the knowledge of using renewable resources in production of unique products that may have leather processing application.
 
 
Microbial Kerainase and its Potential Application in the Management of Tannery Hair Waste 
by A. Onyuka, M. Bates, A. Covington and P. Antunes
Volume: 109      Number: 12     Page: 425-430     Year: 2014
Up to 40 tons of solid hair waste can be generated during the industrial leather manufacturing process posing disposal problems. Composting is considered a viable technology to recycle the hair waste for application in agriculture. However, due to its constituent protein, keratin hair is remarkably resistant to degradation under natural conditions. The aim of this study was to isolate keratin degrading bacteria and evaluate their ability to degrade hair as a preliminary study towards developing a biocatalyst to improve hair degradation during composting. Subsequently, a keratinolytic microorganism was isolated from a nutrient alkaline culture (pH 11) with bovine hair as the source of carbon and nitrogen. The microorganism, identified as belonging to the Bacillus species grew optimally in the temperature range of 40 50C. The partially purified microbial keratinase exhibited broad substrate specificity at pH range 7.5 10. The pH and temperature of optimum activity was determined at 9.0 and 50C, respectively. Scanning electron microscopy assessment of the hair samples showed complete fragmentation of the structure after incubation with the microbial keratinase. Hence, the microbial keratinase has greater potential application as inoculant to enhance biodegradation of tannery solid hair waste during the composting process.
 
 
Elucidation of Probable Mechansm for Biocidal Resistane in Skin-borne Bacillus subtilis 
by S. Kavitha, B. Swarnakuari, N. Chandra Babu, M. Vahini and C. Vandhana
Volume: 109      Number: 12     Page: 418-424     Year: 2014
An attempt has been made in the present investigation to determine the probable mechanism through which a skin-borne bacterium Bacillus subtilis might develop resistance against a dithiocarbamate based biocide. Changes occurring in the cell wall constituents and morphology in the cells grown at sub-optimal level concentrations of biocide were studied based on which the probable mechanism of buildup of biocidal resistance has been proposed. There has been considerable change/reduction in cell wall constituents, peptidoglycan, diaminopimelic acid and teichoic acid due to the presence of biocides. By propidium iodide staining technique, the cell wall permeability has also been found to be reduced. The morphology of the cells as studied using scanning electron microscopy reveals that there is a shortening of rod shape of the cells due to the action of the biocide. Based on the results of the study, it is proposed that the skin-borne Bacillus subtilis encountered in leather processing might develop resistance through changes in the cell wall constituents and reduction in the cell wall permeability.