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Impact of Typical Surfactants on the Collagenolytic and Elastinolytic Activities of Proteases 
by Yanhong Li, Fenfxiang Luo, Biyu Peng and Bingbin Xu
Volume: 110      Number: 7     Page: 227-237     Year: 2015
Most proteases exhibit broad-spectrum activities to all of the protein components of skins, thus, the indiscriminate application of proteases will bring out undue and non-selective loss of skin structural proteins, especially collagen and elastin, and lead to loose and damaged grain. Finding the effective ways to control proteases’ activities against collagen and elastin in leather processes is very important. In this work, the influence of typical surfactants on the collagenolytic and elastinolytic activities of frequently used proteases was investigated, and the mechanism was also discussed. The results indicated that the nonionic surfactants had slight effects and anionic surfactants exhibited quite different behaviors on the collagenolytic and elastinolytic activities of selected proteases. Both collagenolytic and elastinolytic activities of trypsin preparations were obviously inhibited by all selected anionic surfactants, especially SDS and SDBS. For the bacteria proteases, their elastinolytic activities were significantly activated and their collagenolytic activities were inhibited to a variable extent by anionic surfactants. Tanners may effectively control the selective action of proteases to collagen and elastin to achieve different requirements through correctly utilizing surfactants.
 
 
Suitability of Different Oils for Chamois Leather Manufacture 
by K. Sandhya, N. Vedaraman, V. Sundar, R. Mohan, K. Velappan and C. Muralidharan
Volume: 110      Number: 7     Page: 221-226     Year: 2015
Chamois leather, conventionally made using fish oil finds wide industrial application. The major advantage with fish oils is that they contain significant amount of pentadienoic fatty acid in addition to higher iodine value. But the main problem with fish oil is its strong odor and high cost. The objective of the present work is to study the suitability of oils such as linseed oil, castor oil, sunflower oil, animal tallow for chamois leather manufacture in comparision with fish oil. The chamois leather, thus obtained was tested for properties such as sink test, water absorption and strength characteristics. Experimental results show that among different oils, linseed oil based chamois leather posseses higher water absorption and strength properties. It also has mild odour. This study shows that acceptable quality chamois leather can be made using linseed oil as tanning agent instead of fish oil.
 
 
Molecular Identification of Moderately Halophilic Bacteria and Extremely Halophilic Archaea Isolated from Salted Sheep Skins Containing Red and Yellow Discolorations 
by C. Akpolat, A. Ventosa, M. Birbir, C. Sanchez-Porro and P. Caglayan
Volume: 110      Number: 7     Page: 211-226     Year: 2015
Salted hides or skins containing red and yellow discolorations have been examined for many years, but much less information is available about the isolation and molecular techniques for identifying moderately halophilic bacteria and extremely halophilic archaea on the salted sheep skins exhibiting these blotches. The deteriorated salted sheep skins were collected from a warehouse in Spain. Moderately halophilic bacteria and extremely halophilic archaea were isolated from these samples and molecular identification of these microorganisms were performed using 16S rRNA gene sequence analysis. Total cell counts of moderately halophilic bacteria and extremely halophilic archaea were found as 105-108 CFU/g and 105-107 CFU/g, respectively. According to comparative partial 16S rRNA gene sequence analysis, Alkalibacillus halophilus, Pseudomonas halophila, Acinetobacter johnsonii, Alkalibacillus salilacus, Salimicrobium salexigens, Marinococcus luteus and Staphylococcus equorum subsp. equorum belonging to moderately halophilic bacteria; and Halorubrum tebenquichense, Halorubrum saccharovorum, Halococcus dombrowskii, Halococcus qingdaonensis, Natrinema pellirubrum, Halococcus morrhuae, Halorubrum kocurii, Halorubrum terrestre, Halorubrum lipolyticum, Halostagnicola larsenii, Haloterrigena saccharevitans and Natrinema versiforme belonging to extremely halophilic archaea were isolated from these sheep skins. Alkalibacillus halophilus belonging to moderately halophilic bacteria and Halorubrum tebenquichense belonging to extremely halophilic archaea were found as the most common species on the skins. Among the moderately halophilic bacterial isolates, Acinetobacter johnsonii showed lipolytic activities. Among the extremely halophilic archaeal isolates, Halococcus dombrowskii, Halococcus morrhuae, Natrinema pellirubrum, Halorubrum lipolyticum showed proteolytic activity and Halococcus dombrowskii, Halorubrum lipolyticum, Haloterrigena saccharevitans, Natrinema versiforme showed lipolytic activity. Hair slip, red and yellow discolorations, slimy layers and bad odor were detected on the skin samples examined. This study confirmed that salted sheep skins were contaminated by preservation salt containing different proteolytic or lipolytic species of mostly extremely halophilic archaea. Therefore, antimicrobial applications during brine curing of skins should be applied to overcome halophilic microbial damage on the salted skins.
 
 
Determination of Soluble Hexavalent Chromium in Dyed Consumer Goods Improvised by a Simple On-line Color Removal 
by R. Ganeshjeevan, S. Suresh, C. Muralidharan, S. Raja and A. Mandal
Volume: 110      Number: 7     Page: 204-210     Year: 2015
Hexavalent chromium detection in consumer articles is a statutory requirement and screening it in dyes and dyed leather is a challenge. Although many new improvised procedures were put forward, the lack of simplicity and automation leaves the void. The present study addresses these issues and offers a procedure that is closer to automated approach leading to finding that without the requirement of any special device the regular liquid chromatographic instrument can support a quick, simple and efficient method for hexavalent chromium detection in strongly colored leathers. The method was found to be effective in the removal of wide range of dyes and serving the detection of hexavalent chromium in ppb levels with %RSD of max. 3.5.
 
 
Studies on Solubilized Sulfur Dyes for Coloring Leather 
by R. Venba, M. Jawahar, G. Jothi, D. Dakshinamoorthy, A. Deepika, N. Chandra Babu, and K. Ramesh
Volume: 110      Number: 6     Page: 177-185     Year: 2015
Cow wet blue stock was colored with solubilized sulfur dyes in a systematic study to unravel the color yield quality of dyeing and fastness of the dyes. These dyes penetrated the leather cross-section well and this performance resulted in a beneficial tone-in-tone dyeing, which means that the color of the grain, flesh and cross section of leather was almost the same tone. The levelness and uniformity of dyeing were excellent. Their fastness performance was generally very good. The resultant shades suggested that the sulfur dyes were best suited for light, pastel and medium shades, which require a high degree of levelness, penetration and fastness properties. An intense shade resulted from offering the sulfur dyes ahead of the retanning and fatliquoring process steps with a trivial reduction in penetration through the leather cross section for all the ten dyes studied. These findings favor the profitable production of light, medium to dark dye shades on leathers.
 
 
An Assessment of Differences between Butt and Belly Regions of Indian Sheep Skin 
by N. Dagnew, V. Punitha, K. J. Sreeram, J. Raghava Rao and B. U. Nair
Volume: 110      Number: 6     Page: 165-176     Year: 2015
Skins and hides undergo changes in biochemical and biophysical properties during the leather processing. Biochemical composition varies with respect to different portions of the skin like butt, belly, shank, and neck. Belly part looseness is the main problem in leather making from sheepskin. To address this issue, the present work focuses on analysis of histology and biochemical properties of butt and belly portion of sheepskin from the southern part of India. Globular proteins are relatively higher in the butt portion than the belly, whereas it is reverse in the case of fibrous proteins except collagen. Interestingly, the presence of proteoglycans content in butt regions is significantly high compared to belly and in case of fat content it is reverse. Acid soluble collagen contribution is higher in butt region than belly and vice-versa in the case of pepsin soluble collagen. In general, collagen content is significantly higher in butt than belly, which may be the major cause for the higher strength characteristics of butt regions. Cr2O3 content is higher in butt region than belly, which corroborates with protein content and its interaction with tanning agents. Distribution of pore size influences the breathability property of leather, which has been altered in all the unit operations. Scanning electron microscopy study reveals the morphology of the grain and cross-section of the skin changes during leather processing. Thus, this study aids in better understanding of the butt and belly regions of Indian sheepskin.
 
 
Thermochromism for Smart Leathers 
by V. Tamilmani, D. Kanadasan, R. Muthazhagan, K.J. Sreeram, J. Raghava Rao and B. U. Nair
Volume: 110      Number: 6     Page: 161-164     Year: 2015
The Leather industry globally is poised for enhancing the unit value realization. With availability of raw material remaining more or less constant, conferring customer desired smart properties to leather enhances the value of leather. It is also quite possible that such new features would enable leather to enter unexplored territories such as those envisaged for smarter textiles. An innovation in visual stimulus creates immediate appeal and utility, leading to consumer perception of owning it. A survey of such stimulus-based innovations of immediate appeal to people indicated a preference to thermochromism – a reversible color change influenced by temperature. While such applications are predominantly associated with sensor applications, the same as a concept for leather has not yet emerged. This paper reports synthesis of a rare earth doped transition metal complex that had a color shift from pale pink to dark green in the temperature range of 200 – 210oC. This colorant could be applied through conventional finishing techniques on leather and is envisaged to have applications in safety products such as heat resistant gloves.
 
 
A Molecular Level Investigation of Dialdehyde Starch Interaction with Collagen for Eco-friendly Stabilization 
by G. Jayakumar, S. Kanth, J. Ragava Rao and B. Unni Nair
Volume: 110      Number: 5     Page: 145-151     Year: 2015
The current study investigates Dialdehyde Starch (DAS) as a stabilizing agent for collagen. DAS is a well established crosslinking agent for protein; however, molecular interaction with collagen was not elucidated. Dialdehyde involves in the formation of inter and intra crosslinking with protein which renders higher stability against heat and enzyme. Crosslinking efficiency of DAS with collagen was found to increase with increase in the concentration. DAS interacted collagen membrane exhibited an increase in the thermal stability of about 35oC at pH 8. Swelling degree of collage-DAS membranes were found to decrease with increase in the concentration of DAS owing to the shift in the nucleation behavior in collagen fibrillogenesis. DAS treated collagen membrane shows 90% resistance to collagenase due to the unavailability of cleaving sites in collagen-DAS fibres. Reconstittued collage-DAS collagen membranes showed increase in cell proliferation which signifies its non-toxic characteristics. Therefore, DAS can be a new class of green tanning agent for skin stabilization and also finds applications in scaffold preparation.
 
 
Damage of Pickled Hides, Wet-blue Leather and Vegetable Tanned Leather Due to Biodeteriation 
by J. Fontoura and M. Gutterres
Volume: 110      Number: 5     Page: 138-144     Year: 2015
Fungi and bacteria can be responsible for undesirable changes in hides and leather. This study identifies some of the defects caused by fungal growth on pickled hides, wet blue leather and vegetable-tanned leather, such as stains, protein material loss, deterioration of grain layer, and modification of the physical and mechanical properties of resistance. The assessment of the samples exposed to microbiological attack was carried out through visual observation, scanning electron microscopy (SEM), tensile strength test and determination of mass loss. Leather without preservation or treated with insufficient of antimicrobial agent to prevent fungal contamination showed changes in the structure, loss of protein material, a reduction in physical and mechanical properties as well as the presence of stains that may compromise the quality of the final product.
 
 
Carbon Footprint and Toxicity Indicators of Alternative Chromium Free Tanning in China 
by Xiaoying Xu, Grau Baquero, Rita Puig, Jiabo Shi, Jun Sang and Wei Lin
Volume: 110      Number: 5     Page: 130-137     Year: 2015
This paper analyzes, from a life cycle perspective, the environmental performance of a newly developed chromiumfree tanning process compared to the conventional one, in China. Both processes were evaluated by using carbon footprint, energy consumption and toxicity indicators. Chromium-free tanning process has been found to significantly reduce the considered impact categories compared to conventional tanning. The impact contribution of each process step was calculated, with the tanning step being the major contributor. Results show that the production of chemicals used in the tanning process, have a significant effect on the impacts evaluated. Some of these chemicals have been substituted with similar ones (used as proxies) when no manufacturing-data was available in the databases. Thus, it is important for future and more precise LCA studies to develop databases on the specific chemicals used. This study is a first estimation of the impacts and will help on the decision of expending time and efforts on developing and optimizing the new technology. The results show that it is interesting to use this LCA methodology to environmentally evaluate new research processes and products, before industrial scaling and implementing them, to optimize research time and efforts towards the most environmentally promising products and processes.