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An Innovative New Application of Hydrogen Peroxide to Accelerate Chamois Leather Tanning. Part II: The Effect of Oxidation Times on the Quality of Chamois Leather 
by O. Suparno, E. Gumbira-Sa'id, I. Kartika, Muslich and S. Amwaliya
Volume: 108      Number: 5     Page: 180-188     Year: 2013
The use of oxidizing agent, such as hydrogen peroxide, was reported to shorten the oxidation process time of chamois tanning. Appropriate conditions for this tanning are needed in order to improve its process efficiency, and to obtain a satisfactory leather quality. The objectives of our study were to investigate the effects of oxidation times in chamois tanning on the quality of the resulting leather, and to determine the best condition of the oxidation time. The experiments were conducted by tanning pickled goatskin for 4, 6, and 8 hours oxidation times inside a rotary drum, and 1, 2, and 3 days of oxidation times outside the drum. The physical, chemical, and organoleptic properties of the leathers were then tested. This study showed that they fulfilled the quality requirements for chamois leather. The best conditions for oxidation were oxidation times of eight hours inside, and one day outside a rotary drum. Therefore, the use of hydrogen peroxide oxidizing agent shortened the oxidation process outside the rotary drum in chamois leather production from nine to two days.
An Examination of Inactivation Efficacy of NaCl and Boric Acid on Bacteria Isolated from Salted Hides 
by M. Birbir, R. Cicek, P. Caglayan and E. Aslan
Volume: 108      Number: 5     Page: 171-179     Year: 2013
Due to isolation of bacteria in high number on the salt-pack cured hides in our recent studies, the inactivation efficacy of different concentrations of NaCl and Boric acid, used as curing agents, on Gram-positive (Staphylococcus epidermidis and Enterococcus faecium), Gram-positive endospore forming bacteria (Bacillus pumilus and Bacillus licheniformis), Gram-negative bacteria (Pseudomonas aeruginosa and Pseudomonas fluorescens) and the mixed culture of these isolates was investigated. These proteolytic and lipolytic bacteria were isolated from the salted hides. Inactivation efficacy of NaCl and Boric acid on the bacteria was examined in Nutrient Broth and Nutrient Agar media containing 5%, 10%, 15%, 20%, 25%, 30% NaCl; 1%, 2%, 3%, 4%, 5%, 7% Boric acid; and both 5%, 10%, 15% NaCl and 1% Boric acid. In addition, the test bacteria were inoculated in Nutrient Broth containing 20%, 25%, 30% NaCl and 2%, 3%, 4%, 5%, 7% Boric acid and incubated for 24 hours at 35oC. Afterwards, viable bacterial cell counts were determined on NaCl-free Nutrient Agar and boric acid-free Nutrient Agar. The data obtained from this study showed that bacterial growth was prevented by high concentrations of NaCl and boric acid, but the bacteria were still alive and complete destruction of the test bacteria was not accomplished. When NaCl and Boric acid were removed from the hides with the first soaking process, bacteria on the hides may damage the hides during a long main soaking process. As a conclusion, more effective antibacterial treatments should be applied to fresh hides to completely destroy proteolytic and lipolytic bacteria on hides.
A Novel Technique for Getting Leather Section Image Based on Metallographic Sample Preparation 
by Huayong Zhang, Yongmei Xia, Jinyong Cheng, Lei Shi and Tianduo Li
Volume: 108      Number: 5     Page: 166-170     Year: 2013
In this paper, the procedure of improved metallographic sample preparation used to reveal the true structure of the chrome tanned crust leather was described for the first time. E-51 epoxy resin was selected as leather embedding medium. The surface of the prepared samples was examined on an optical Microscope (Olympus BX51) using light reflection model, and the micrographs illustrating the shape and the directions of fiber bundles were obtained. This novel technique offers significant advantages over conventional one.
Enzymes in the Leather Industry, a special review paper 
by A. Dettmer, P. Schacker Dos Anjos and M. Gutterres
Volume: 108      Number: 4     Page: 146-158     Year: 2013
The leather industry has been facing new challenges including the need to improve and optimize processes to achieve the required quality in their final articles and meet the requirements of environmental legislation. The enzymatic treatment of leather is a promising technology. Enzymes are organic substances, generally proteins, known as biocatalysts for multiplex chemical reactions. They have been explored commercially in the detergent, food, pharmaceutical, diagnostic, fine chemical and other industries. Commonly, the most promising enzyme sources are microorganisms. Several studies have reported enzyme use in different stages of leather production, describing a decrease in the use of chemicals for the depilation and liming steps, and some have also reported the complete replacement of chemicals with enzymes. Some authors use enzymes to increase the exhaustion of dyes in dye baths and to increase the effectiveness of tanning in the tanning step. The identification of a new enzyme is a long process, requiring screening for specific criteria, isolation and selection of new bacteria, and the investigation of the nutrients and conditions necessary for growth and enzyme production by the selected microorganism. Finally, issues such as pH, temperature and product inhibition of the enzyme during its application in the processing of skins/hides should be studied.
Effects of Level ad Length of Supplementation on Leather Characteristics of Yearling Boer and Spanish Wethers 
by R. Merkel, C.-K. Liu, N. Latona, Anton El Amma and A. Goetsch
Volume: 108      Number: 4     Page: 139-145     Year: 2013
Thirty Boer × Spanish and 29 Spanish wethers were used in a trial to determine the effects of goat breed, supplementation level, and age on the mechanical properties of chrome-tanned and glutaraldehyde-tanned goat skin. Six Boer and five Spanish wethers were harvested at the beginning of the trial with the remaining animals assigned to four groups, having equal breed numbers, receiving either a high or low supplement amount daily. Two groups were harvested after 110 days and the remaining groups after an additional 108 days. Skins were removed by hand, split down the dorsal midline, and salted. The left half of each skin was chrome-tanned and the right half was tanned using a glutaraldehyde based tannage. Tanning goat skins using chromium resulted in stronger leather than that produced using glutaraldehyde. Increasing age led to decreased % elongation and increased leather stiffness. The effects of supplementation level were of lesser importance than tannage or age upon the strength characteristics of leather produced. Boer goat leather was thicker than Spanish goat leather; although tensile strength was unaffected by breed. Goat skins were not shaved to an equal thickness during the tanning process, perhaps leading to some of the breed differences seen, notably in % elongation and fracture energy. Therefore, further research is needed to evaluate characteristics of shaved skins.
Evaluation of Hides, Wet Blue and Leather Using Airborne Ultrasonics 
by C.-K. Liu, N. Latona and S.-C. Yoon
Volume: 108      Number: 4     Page: 128-138     Year: 2013
Animal hides are important agricultural commodities closely associated with rural economics and the well being of rural farmers in the United States. Approximately 90% of the hides produced in the United States are being exported; the remaining 10% are mostly tanned into leather. At the present time hides and leather are visually inspected and ranked for quality, usable area, and sale price. However, visual inspection is not reliable for detecting defects, which are usually hidden inside the material or under the hair in fresh hides. This manual assessment is not uniform among operators, and often leads to disputes over fair price. Development of a non-contact nondestructive method to accurately evaluate the quality of hides and leather is urgently needed. We previously reported the research results for airborne ultrasonic (AU) testing using non-contact transducers to evaluate the quality of hides and leather. We demonstrated the ability of AU to reveal defects in hides and leather that are difficult to be found during visual inspection. In this paper, we present new results on AU inspection, particularly using a statistical data/cluster analysis technique, in which leather and hide defects are depicted as color-coded amplitude maps, or “C-scans
Removal of Calcium from Pelt During Bating Process: An Effective Approach for Non-ammonia Bating 
by Ya-nan Want, Yunhang Zeng, Xuepin Liao, Wenhua Zhang and Bi Shi
Volume: 108      Number: 4     Page: 120-127     Year: 2013
Ammonium salts can improve the performance of bating by trypsin. But it is one of the main origins of ammonia nitrogen (NH3-N) in tannery wastewater. In this study, the action mechanism of ammonium sulfate (AS) on trypsin bating was investigated. It was found that the activity of trypsin was actually not influenced by AS (1~30 g/L) or pH variation caused by the addition of AS. In fact, the activity of trypsin was partially inhibited by calcium remained in pelts, particularly those concentrated in the grain layer. The main function of AS in bating is to remove calcium so as to maintain the proteolysis activity of trypsin. Based on these findings, several calcium chelating agents, including sodium hexametaphosphate and the composite of sodium citrate and citric acid, were employed in the trypsin bating process. The extents of calcium removal from pelts by using these chelating agents were higher than AS, and the bating performances were better in terms of protein and hydroxyproline contents in bating liquor.
The Odor of Leather 
by M.Schröpfer, M.Czerny, H.Schulz and P.Schieberle
Volume: 108      Number: 3     Page: 94-107     Year: 2013
Leather has a typical odor that varies depending on the type of leather. Whereas many other materials should preferably be odorless, a typical leather odor is desired. It is an important quality feature. So far the compounds causing the leather odor could not be clearly defined. For this research work, different leathers from different application areas were chosen. Depending on the manufacturing technology the leathers showed different nuances of leather odor. Published herein are the results from analysis of leathers by Gaschromatography-Odorimetry (GC-O), Aroma-extract-dilution analysis (AEDA), Gaschromatography-Mass-Spektrometry (GC-MS) and Stable-Isotope-Dilution-Analysis (SIDA) for identifying and quantifying substances accountable for certain leather odors. Furthermore, it points out from which stages of leather manufacturing the leather odor originates and if it can be influenced. Alternative methods for identification and quantification of substances relevant to odor are discussed regarding their significance. RESUMEN El cuero tiene un olor típico que varía en función del tipo de cuero. Mientras que muchos otros materiales preferentemente deberían ser inodoros, un típico olor a cuero es deseable. Es una característica importante de calidad. Hasta ahora, los compuestos que provocan el olor de cuero no pudo ser claramente definido. Para este trabajo de investigación, distintos cueros de diferentes áreas de aplicación fueron elegidos. Dependiendo de la tecnología de fabricación, los cueros mostraron diferentes matices de olor a cuero. Publicado en este documento se presentan los resultados del análisis de los cueros mediante Cromatografía de gases-Odorimetría (GC-O), Análisis de dilución de extracto de aroma (AEDA),Cromatografía de gases y Espectrografía de Masas (GC-MS) y Análisis de dilución de isótopos estables (SIDA) para identificar y cuantificar las sustancias responsables de ciertos olores de cuero. Por otra parte, señala a partir de qué etapas de fabricación del cuero se origina el olor y si pueden ser influenciados. Métodos alternativos para la identificación y cuantificación de sustancias relevantes para el olor se discuten con respecto a su significado.
Volume: 108      Number: 3     Page: 86-93     Year: 2013
The use of ¦Á-amylase preparations (AP) in sulfide and lime free unhairing systems has recently received renewed interest. However, the mechanism of AP action on hides or skins remains unclear. AP is generally a mixture of ¦Á-amylase and concomitant protease(s), and it is not yet known which components of AP are effective in unhairing. To investigate whether ¡°pure¡± ¦Á-amylase or concomitant protease(s) are mainly responsible for unhairing, a protease-free ¦Á-amylase preparation (PFAP) and an amylase-free ¦Á-amylase preparation (AFAP) were prepared by selective inactivation of protease(s) and ¦Á-amylase in AP respectively. AP, PFAP and AFAP were employed for unhairing of cattle hide for 4 h at 25 oC, and their effectiveness of unhairing was evaluated by analyzing the extent of removal of hair, epidermis and protein from hide. The results indicated that rather than ¡°pure¡± ¦Á-amylase, the concomitant protease(s) in AP were the effective components for unhairing. This suggests that the mechanism of AP action on hides should be consistent with the mechanism of enzymatic unhairing with proteases. RESUMEN El uso de preparados ¦Á-amilasa (AP) en sistemas de pelambre libres de sulfuro y cal ha recibido recientemente un renovado inter¨¦s. Sin embargo, el mecanismo de acci¨®n de AP en las pieles sigue siendo poco clara. AP es generalmente una mezcla de ¦Á-amilasa y proteasa(s) concomitantes, y todav¨ªa no se conoce cu¨¢l de los componentes de AP son eficaces en el depilado. Para investigar si la ¦Á-amilasa "pura" o proteasa(s) concomitantes son responsables principalmente del depilado, una preparaci¨®n de ¦Á-amilasa libre de proteasa (PFAP) y una preparaci¨®n libre de ¦Á-amilasa (AFAP) fueron preparados mediante la inactivaci¨®n selectiva de las proteasa(s) y ¦Á-amilasa en AP, respectivamente. AP, PFAP y AFAP fueron empleados en el depilado de cuero vacuno durante 4 horas a 25oC, y su eficacia en el depilado se evalu¨® analizando el grado de eliminaci¨®n de pelo, epidermis y prote¨ªnas de la piel. Los resultados indicaron que en lugar de la ¦Á-amilasa "pura", la proteasa(s) concomitantes en AP fueron los componentes eficaces en el depilado. Esto sugiere que el mecanismo de acci¨®n de AP en pieles debe ser consistente con el mecanismo de depilado enzim¨¢tico con proteasas.
by C.K. Liu, N. Latona, M. Taylor and R. Latona
Volume: 108      Number: 3     Page: 79-85     Year: 2013
The U.S. hides and leather industries are facing many challenges today, such as overcoming relatively high U.S. energy and labor costs; meeting environmental imperatives; quantifying, maintaining, and improving current hides and leather product quality; developing new processes and products; and improving utilization of waste. One of our efforts to address these new challenges is to develop new uses and novel biobased products from hides to improve prospective markets and to secure a viable future for the hides and leather industries. We hypothesize collagen fiber networks derived from un-tanned hides can be utilized to prepare high performance green composites and air filters, of which both have a great market potential. This study focused on understanding the effects of processing steps such as bating, pickling and crosslinking treatments on the morphology and physical properties of the fiber networks derived from un-tanned hides, which will be the starting material for constructing air filters and green composites. Results showed that glutaraldehyde treatment yielded a highly open structure, in which the fibers are well separated from each other. This could be attributed to the action of acids during the pickling step. RESUMEN Las industrias de las pieles y los cueros de Estados Unidos se enfrentan a muchos retos hoy en día, tales como los abrumantes altos costos relativos de energía y mano de obra en los Estados Unidos; satisfacer los imperativos medioambientales; cuantificar, mantener y mejorar la calidad de las pieles y los actuales productos de cuero, desarrollar nuevos procesos y productos, y mejorar la utilización de los residuos. Uno de nuestros esfuerzos para hacer frente a estos nuevos desafíos es el desarrollo de nuevos usos y nuevos productos de base biológica de las pieles para mejorar los mercados de futuros y para asegurar un futuro viable para la industria de pieles y cueros. Se plantea la hipótesis que redes de fibra de colágeno derivadas de pieles no curtidas se pueden utilizar para preparar compuestos ecológicos y filtros de aire de alto rendimiento, de los cuales ambos tienen un gran potencial de mercado. Este estudio se enfoca en la comprensión de los efectos de las etapas de procesamiento tales como rendido, pickelado y tratamientos de reticulación sobre la morfología y las propiedades físicas de las redes de fibra derivadas de pieles no curtidas, que serán el material de partida para la construcción de filtros de aire y compuestos ecológicos. Los resultados mostraron que el tratamiento con glutaraldehído produjo una estructura muy abierta, en la que las fibras están bien separados unas de otras. Esto podría atribuirse a la acción de los ácidos durante la etapa de pickelado.