Application of acidic protease in the pickling to simplify the pelt bating process

Abstract

Traditionally, universally used pelt bating technologies rely on the application of trypsin, neutral and alkaline microbial proteases but suffer from complicated operation, limited bating efficiency and unsatisfactory leather performance. Therefore, devising a new pelt bating approach to achieve high bating efficiency and excellent leather performance has always been wished for by the leather industry. To pursue this goal, years of persistent research work enabled us to develop a novel approach for pelt bating by means of acidic proteases in pickling process. Initially, basic enzymatic characteristics and bating effectiveness of several typical acidic proteases in pelt pickling medium were investigated; then, the bating effectiveness through the quantitative characterization of protease activity of the optimal acidic protease was compared with that of the conventional bating enzyme. The results indicated that all of the selected acidic proteases had good salt-tolerance and exhibited optimum activity at pH 3.0–4.0. The novel pickling-bating method based on microbial origin acidic protease L80A led to an outstanding performance on pelt bating at the dosage of 150 U/mL of collagenolytic activity. The bating effectiveness of acidic protease L80A was comparable to and even better than that of trypsin BEM due to its moderate proteolytic ability. Moreover, the deep and even penetration of acidic protease in the pelt permitted it to produce soft, organoleptically stable and overall better quality crust leather than that of the conventional trypsin bating method. Additionally, pelt bating was performed along with the pickling process without extra inactivation and washing operation, making the bating operation more efficient, economical, and environment friendly. Results had made us to conclude that this cutting-edge acidic proteases based pickling-bating method could be the first step/ way forward to replace the decades-old traditional pelt bating technology.

Osmanthus fragrance polyurethane/silkfibroin‐based double‐shellmicrocapsules for aromatic leather with sustained release fragrance

“…Leather is an important material for upholstery, apparel and automotive interiors 1 . However, the usage of many chemical agents in the complex manufacturing process of the leather produced the undesirable odour and reduced the value of leather products 2–6 . Hence, the direct addition of fragrances in leather is critical to cover the unpleasant smell and prepare aromatic leather commodities 7 .…”

“…1 However, the usage of many chemical agents in the complex manufacturing process of the leather produced the undesirable odour and reduced the value of leather products. [2][3][4][5][6] Hence, the direct addition of fragrances in leather is critical to cover the unpleasant smell and prepare aromatic leather commodities. 7 Fragrances including terpenes, esters, phenols and other compounds were prone to volatilize, lose and degrade when exposed to the surroundings of light, heat and oxygen, hindering the sustained release of the aromatic leathers during storage and usage.…”

Wet Blue Enzymatic Treatment and Its Effect on Leather Properties and Post-Tanning Processes

“…Furthermore, non-collagenous proteins remaining in hide can cause a lack of flexibility and firmness in dried leather [ 4 ]. For interfibrillar substances, the removal of alkaline or neutral proteases is carried out; nevertheless, new studies show the possibility of acid protease application in bating [ 7 , 8 , 9 , 10 ]. Currently, proteases used in bating are derived from non-hazardous microorganisms.…”

“…Širvaitytė et al, used acidic enzymes in pelt bating after de-liming with peracetic acid; the process results indicating the suitability of acidic protease in bating [ 10 ]. Other researchers have reported promising results in pickling–bating processes [ 7 , 14 , 15 ], where enzymes were used in a pickling solution after bating, or two processes were combined together.…”

“…Although re-bating can improve the finished product, the process requires a higher enzyme concentration and a longer operating time [ 7 ]. As a result, it is important to determine the properties of the leather after re-bating, as well as the effect on the following processes, such as re-tanning, dyeing, and fat-liquoring.…”