Characterization and application of dried neem leaf powder as a bio-additive for salt less animal skin preservation for tanneries.

Sodium chloride (NaCl) is commonly used as a curing/preservative agent for raw hides and skins in tanneries and is removed through a soaking process with total dissolved solids (TDS) and other organic pollutants in effluent, causing significant pollution load to the environment. Hence, the present study evaluated to apply dried neem leaf powder (DNL) as an additive to reduce the usage of salt in skin processing and preservation. To make certain of DNL antimicrobial properties, solvent extracts were performed against proteolytic bacteria isolated from raw skins. Initial characterization of DNL revealed the presence of bioactive compounds nimbolide and dehydro salannol and acetone extract with 16.9-mm, 10-mm and 8-mm zone of inhibition against Salmonella sp., E. coli sp. and Bacillus sp. identified using phenotypic conventional biochemical screening method. Further, skin curing experiments were carried out using four different treatments of DNL (10% 15%, 20% and 25% w/w) along with 15% w/w of conventional salt to obtain an optimum concentration for pilot-scale studies. Thus, the application of optimal DNL (15%) and salt (15%) resulted in no physical changes such as smell and hair slip and was taken for further studies for hydroxyproline activity, pollution load and organoleptic properties along compared with control 40% salt. DNL-aided salt less preservation of freshly flayed goat skins at ambient condition showed no hair slip or putrefaction during the preservation period with significant reduction of TDS (86%) and chloride (71%) in soak liquors compared to conventional salt preservation and enhanced organic load requiring additional treatment. However, the application of the organoleptic, physical and hydrothermal properties of resulting leathers produced from the DNL applied skins was on par with results of leather obtained from conventional salt. Thus, our results demonstrate DNL-aided salt less preservation method is able to reduce the amount of salt for preservation of goat skins significantly, leading to reduced salinity issues during leather processing.

Studies on the use of sodium polyacrylate (SPA) for low-salt animal skin preservation.

Salt-based preservation is practiced for decades in the leather industry because of its versatility, cost-effectiveness, and availability. The salt removed from the soaking process causes significant pollution including organic and elevated total dissolved solids (TDS). Hence, a low-salt skin preservation method using commercial sodium polyacrylate with a reduced quantity of sodium chloride aiming to retain leather properties and pollution reduction was the principal focus of the study. Commercial sodium polyacrylate initially characterized for water absorption capacity along with structural and functional properties is confirmed by NMR and IR spectroscopic techniques. In preliminary experiments, the process parameters attained optimized conditions of sodium polyacrylate (SPA) quantity (5%), a minimal amount of salt (15%), and contact time (4 h) required for skin preservation. Besides, reusability studies after SPA recovery (95%) were applied to skins with an optimized quantity of SPA and salt subsequently stored for 15 days along with control (40% salt). The results revealed that SPA with low salt aided an adequate curing efficiency with a substantial reduction (> 65%) of TDS and comparable physical and organoleptic properties on par with the conventional method. Overall, SPA supported low-salt skin preservation reduces pollutant load (TDS) caused due to using of 40% sodium chloride in the conventional curing process.