Biodeterioration of chrome-tanned leather and its prevention strategies

Preventing biodeterioration of chrome-tanned leather due to mold growth during storage is critical in the leather industry. In this paper, Differential Scanning Calorimeter (DSC), Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), Liquid Chromatography-Mass Spectrometry (LC-MS) and characteristic components analysis were used to analyze the biodeterioration process and mechanism of the chrome-tanned leather. Feasible strategies to improve the biodeterioration prevention effect were explored in detail from the aspect of tanning-basification processes and the selection of fungicides. The results showed that molds grow and reproduce by using the available proteins, fats and carbohydrates in the chrome-tanned leather as nutrient resources, metabolizing and secreting alkaline substances such as histamine and spermine, and proteases, simultaneously. The macromolecular organic matter was hydrolyzed into small molecular substances and provided nutrients for microorganisms, meanwhile, the increase of environmental pH caused the dechroming of tanned collagen fiber, accelerating the degradation of collagen fiber, making tanned leather more easily destroyed. Furthermore, the use of a proper amount of MgO for basification was not likely to cause a continuous increase in the pH of the chrome-tanned leather during storage, and the pH of the leather eventually stabilized at about 4.0 during long-term storage. Additionally, the use of 100 mg/L of fungicides MIT, CMIT, IPBC and OIT can effectively kill molds and continuously inhibit the development of mold spores during the storage procedure, which is an effective way to solve biodeterioration of chrome-tanned leather. Hence, this study provides theoretical support for effectively solving the problem of biodegradation of chrome-tanned leather caused by mold growth and reproduction, which could reduce the hazard to the environment while reducing the production cost of tanneries and improving the economic benefits.