The effect of Aspergillus sp. as a bating agent in tanned goat’s skin on bending strength, paint fade, and protein level

Bating is a process of eroding proteins carried out in the process of tanning the skin to erode protein on the skin using protease activity. Feliderm is commonly used as a bating agent. However, the disadvantages of feliderm are relatively high cost, access to purchases is quite difficult, and not being environmentally friendly. Aspergillus sp. is widely known by the public for its use in fermenting soybeans to soy sauce, which is one of the producers of protease enzymes that can be utilized. The method used was an experimental trial using a Completely Randomized Design with 5 treatments and 3 replications, if there were significant influences followed by Duncan’s Multiple Range Test Method. The results show that Aspergillus sp. can be used to replace feliderm as a bating agent on goat’s skin leather tanning. The best result is T4 with the bending strength showing Nerf and the paint not cracking, the paint not fading at the value of 4/5, and the protein content with the value of 70,91%.


Introduction
Goat skin is leather that is usually used as a raw material to make leather puppets or shoes and jackets.The leather tanning industry is an industry that processes leather raw materials (hides and skin) into leather or tanned materials using chemicals that support the tanning process.Processing raw leather into tanned materials can make the leather resistant to the effects of microorganisms, chemical and physical [1].The tanning industry uses chemical and vegetable tanning agents in the tanning process.The tanning process using chemicals will produce leather products for jackets, sofa blankets, motorbike seats, and car seats.Meanwhile, tanning using vegetable tanning materials will produce products in the form of wallets, book covers, and shoe soles [2].
Batting (protein scraping) is the most important process in tanning because in this process the collagen protein will determine the results of the tanning so that the protein scraping agent (batting agent) plays a role in eroding non-collagenous proteins on the skin to obtain finished skin that has a high suppleness.good and to remove these proteins protein decomposing enzymes are needed.The proteineroding agent commonly used in the batting process is feliderm which is made from a protease enzyme in the form of a white powder that minimizes damage to collagen.However, the disadvantages of feliderm are expensive prices, access to purchases that are quite difficult, and not being environmentally friendly [3].
Aspergillus sp. can break down complex fats into triglycerides and proteins.In addition, this fungus is also capable of producing protease enzymes and branching like a fork, smooth-walled, has a length of 150 -2000 µm and a diameter of 6 -14 µm.The protease enzyme activity in Aspergillus sp. in eroding 1302 (2024) 012077 IOP Publishing doi:10.1088/1755-1315/1302/1/012077 2 protein can produce 392.89 µ/mg protein [4].Therefore, this research focuses on the effect of the concentration of Aspergillus sp. and feliderm on the protein erosion process on goat skin.

Location and time of research
This research is located at the Yogyakarta Leather, Rubber and Plastics Center (BBKKP) and some tests were carried out at the BBKKP and the Leather Waste Development and Processing Laboratory (LP3K).

Materials
The research material used 20 pieces of goat skin which were obtained from the RPH in the city of Yogyakarta.Aspergillus sp.obtained from the Airlangga University Laboratory of Sciences.

Results and Discussion
The test results for bending strength, paint fading, and protein content can be seen in Table 1.
Table 1.Physical and chemical characteristics of tanned-goat skin using Aspergillus sp. as a batting agent (the data is processed by the authors).

Bending strength
The results showed that treatment T0 (feliderm 2%) produced Nerf and the paint did not crack, treatment T1 (Aspergillus sp.0.5%) produced Nerf and the paint did not crack, treatment T2 (Aspergillus sp.1%) produced Nerf and the paint did not crack, treatment T3 (Aspergillus sp 1.5%) produced Nerf and the paint did not crack, T4 treatment (Aspergillus sp.2%) produced Nerf and the paint did not crack.This is because the processed leather structure has a strong structure so that there are no Nerf cracks and the paint sticks tightly.The strong bending strength will affect the sewing process and product manufacturing because later the leather will be folded into bags, shoes, wallets, or other products.Skin that has a defective Nerf will hinder the process of making the product because the skin will be discarded and will harm the craftsmen, cracked paint on the skin can be detrimental because it will reduce the selling value of leather products.The bending strength of leather can be influenced by changes in the structure of skin fibers during tanning [5].

Paint fade
The results obtained from the test were that T0, T3, and T4 did not fade and got the same score of 4/5 while T1 and T2 with slightly faded results and got a score of 3/4.The results obtained show that samples of T0, T3, and T4 can survive dry conditions.Based on ISO 20433: (2012) the color fastness value is at a score between 1 to 5, a value of 1 means the color is lost dominantly and a value of 5 means no color is lost.Leather finishing is the final stage in the leather tanning process which will determine the appearance of the finished product [6].The purpose of finishing includes providing an attractive appearance.Binder or adhesive material in the leather tanning process is often used in the leather finishing/cover paint process.The paint will bond firmly to the surface of the leather so that, when tested for rubbing resistance with wet and dry cloth, it will not fade.The paint resistance of the "dyeing agent" is determined by the molecular weight, and the molecular size of the "dyeing agent".Mixing of 3 valence chrome with skin protein via hydroxyl (OH) clustering bridge [7].

Protein Content
The results of the analysis of variance showed that the effect between treatments was not significant (P>0.05).This indicates that skin batted using Aspergillus sp. can provide the same batting results as using Palkobat (batting agent).The chemical composition of raw or fresh hides is related to the levels of protein, fat, carbohydrates, minerals, and water.The composition of each chemical substance that makes up the components of the skin varies depending on the type of livestock, age, food, climate, and living habits of the livestock itself.The chemical composition of the skin includes 65% water, 33% protein, 0.5% minerals, and 2-30 % fat.The chemical composition is not constant, but it depends on the type of skin [8].The results of protein levels after batting obtained an average of 73.04% at T0, 72.14% at T1, 71.08% at T2, 70.77% at T3, and 70.91% at T4.The difference in results in batting is not influenced by enzyme concentration but also by the length of batting.The T3 treatment is the lowest and the best result compared to the others because 1.5% of Aspergillus sp. is used.Aspergillus sp. has high protease activity so it was able to erode globular proteins in the skin.Treatments T1, T2, and T3 showed results that were not too different because they both used Aspergillus sp. as batting.Aspergillus sp. has a proteolytic activity of 392.89 μ/mg protein [4].Protease activity in all batting agent concentration treatments can degrade non-collagen proteins which inhibit the penetration of tanning agents into skin tissue [9].

Conclusion
The conclusion of this research is Aspergillus sp. can be used to replace feliderm as a bating agent on goat's skin leather tanning.The bending strength had good results, but no significant difference between T0 (control) and all Aspergillus sp.concentrations.The best result is T4 with the paint not fading at the value of 4/5 and the protein content with the value of 70.91%.