Salt-pack curing is the most widely used method to preserve hides. However, inadequately applied salt-pack curing method supports the growth of proteolytic and lipolytic bacterial and archaeal flora which may reduce the quality of leather. Therefore, to examine the efficacy of salt-pack curing method applied to hides and to determine harmful microorganisms of the hides, Gram-negative bacteria on the salt-pack cured hides were isolated and identified and their proteolytic and lipolytic activities were investigated in the present study. Salt-pack cured hides examined were collected from different tanneries in Leather Organized Tannery Region, Tuzla-Istanbul, Turkey and 40% of the hides were imported from abroad. A total of 256 Gram-negative bacterial isolates containing 21 different genera (Acinetobacter, Aeromonas, Alcaligenes, Burkholderia, Citrobacter, Comamonas, Edwardsiella, Enterobacter, Escherichia, Hafnia, Klebsiella, Mannheimia, Pasteurella, Proteus, Pseudomonas, Salmonella, Serratia, Sphingomonas, Stenotrophomonas, Vibrio and Yersinia) and 46 different bacterial species were isolated and identified from the hide samples. The percentage of proteolytic, lipolytic and both proteolytic and lipolytic Gram-negative isolates on the hides were found as 68%, 52% and 43%, respectively. The most common Gram-negative genera on the salt-pack cured hides were Enterobacter (66), Pseudomonas (59) and Vibrio (32). These isolates showed both proteolytic and lipolytic activities in the highest number on the hides. As a conclusion, the hides contained a wide variety of destructive Gram-negative bacterial species originating from different environmental sources and traditional salt-pack curing method was not sufficient to inactivate these Gram-negative bacteria.
This work presents the results of a Gas Chromatography methodology used to characterize and quantify the major fatty acids of bovine tallow. Tallow is a byproduct from processing waste meat in slaughterhouses and from tannery waste. Tallow has a high commercial value, especially when fractionated to olein that is predominantly composed of unsaturated fatty acids. Olein is used as a raw material for the production of leather fatliquoring emulsions or biodiesel production. The fatty acids of tallow and its products of fractionation were first converted to methyl esters, and these esters were then analyzed by Gas Chromatography. The results showed the major fatty acids and their weight distribution. This analytical methodology will allow a quality assessment of tallow by the end user industry. It is also a reliable quantitative tool to evaluate the efficiency and optimization of the tallow fractionation processes.
Alkyl phenol ethoxylates (APEO) in general, nonyl phenol ethoxylates (NPEO) and octyl phenol ethoxylates (OPEO) in particular, are nonionic surfactants, which are widely used as components of a range of leather chemicals. APEO have a low biodegradable rate, reported as 0-9% per year, and are known to generate most persistent and toxic metabolites. In this study, APEO containing wetting agents and fatliquors have been chosen and treated with leather separately at various concentrations. The amount of APEO present in the treated leather was mapped based on their concentration of application. The results show that the APEO content in the leather increases with the increase in the concentration of fatliquor or wetting agent containing APEO. An attempt has also been made to adopt some special treatment methods in post tanning process such as treating with formic acid at elevated temperature and use of specific enzymes to reduce APEO content in the final leather. Formic acid treatment led to poor APEO reduction as well as unsatisfactory leather quality. Out of the different oxidizing enzymes employed, horseradish peroxidase treatment on APEO containing leathers resulted in 60% APEO removal. It has also been observed that the physical and bulk properties of the leathers treated with enzymes are satisfactory compared to the control leathers. This study shows, for the first time, a way for an efficient eco-friendly treatment method for removing APEO from leathers.
A change of molecular structure improves the surface active efficiency of new generation gemini surfactants. As a result, it was confirmed that the dosage could be reduced considerably in industrial applications as performance chemicals, leading to economically quantifiable benefits. The performance of newly synthesized gemini surfactant based sulfonated dimeric malenised soya fatty acid bridged with butane diol was evaluated as a leather fatliquor. The chemical parameters of the fatliquors were analysed and tested on leather. The properties imparted by the fatliquor to leather were studied qualitatively and quantitatively. SEM studies of the treated leathers revealed better penetration of the gemini surfactant based fatliquor compared to the control. Results were correlated in terms of emulsification power, zeta potential and particle size of the surfactants, found to be better than the conventional surfactant. The surface energy was calculated for the fatliquors and found to be equal.