Pretreatment evaluation of gallic acid tuned nanosilver for short-term preservation of goat skins in leather processing

Leather is the transformed product obtained from processing of raw skins and hides flayed from animals. Proteins, being the main constituent of the raw materials with about 70% moisture, are prone to microbial attack. Preservation of the raw materials is quintessential to retain the protein matrix for successful leather production. Common salt to the extent of 40–50% w/w is a widely practised method of preservation. Although effective, this approach generates huge amount of pollutants in the form of total dissolved solids (TDS) and chlorides demanding alternative curing systems. In this view, gallic acid–capped silver nanoparticles (GA@AgNPs) were evolved to serve as an alternative curing system for broad-spectrum antimicrobial and pollution abatement under optimized conditions. Nanocharacteristics were studied using UV–vis spectroscopy, X-ray diffraction (XRD), and electron microscopic (EM) analysis. Antimicrobial susceptibility testing was performed using an array of microbes isolated (n = 15) from flayed goat skin, and minimum inhibitory concentration/minimum bactericidal concentration (MIC/MBC) was determined. The preservation efficacy of GA@AgNPs and salt (40%) challenged against goat skin was demonstrated and the leather characteristics validated after 30 days of treatment. Possible mechanism involved in curing process was deciphered using EM studies. GA@AgNPs were prepared under optimized conditions in a rapid fashion that typically revealed surface plasmon resonance with λmax 406 nm, crystalline phase, and spherical and anisotropic particles of size < 40 nm. Significant antimicrobial activity was exhibited upon exposing individual microbe and consortia at 1 mg/mL of GA@AgNPs. Antimicrobial mechanism via membrane damage was clearly elucidated using EM studies. The preservative efficacy of GA@AgNPs at 10% (v/w) was well-established from its water repelling efficacy and broad-spectrum antimicrobial activity owing to their strong zeta potential (− 31.4 mV) conferred by gallic acid. Therefore, GA@AgNPs might find its application in leather industry as an alternative curing system prior to trials and challenging adverse environmental conditions.