Recovery of Gelatin from Bovine Skin with the Aid of Pepsin and Its Effects on the Characteristics of the Extracted Gelatin.

Tanbir Ahmad,Elmutaz Atta Awad,Muhammad Tayyab Akhtar,Amin Ismail,Awis Qurni Sazili,Khalilah Abdul Khalil,Siti Aqlima Ahmad

doi:10.3390/polym13101554

Abstract

Pepsin enzyme was used to pretreat the bovine skin at the rate of 5, 15, and 25 units of enzyme/g of skin to recover gelatin, and the recovered gelatins were referred to as Pe5, Pe15, and Pe25, respectively. The gelatin yield increased significantly (p < 0.05) from 18.17% for Pe5 to 24.67% for Pe25 as the level of pepsin increased, but the corresponding gel strength and viscosity decreased significantly (p < 0.05) from 215.49 to 56.06 g and 9.17 to 8.17 mPa·s for Pe5 and Pe25, respectively. β- and α1- and α2-chains were degraded entirely in all the gelatins samples as observed in protein pattern elaborated by gel electrophoresis. 1H nuclear magnetic resonance (1H NMR) analysis indicated the coiled structure of gelatin protein chains. The lowest amide III amplitude of Pe25 as found by Fourier transform infrared (FTIR) spectroscopy indicated that α-helix structure of protein chains were lost to more irregular coiled structure. Thus, it could be summarized that pepsin might be used at the lower level (5 units/g of wet skin) to extract gelatin from bovine skin with good functional properties and at higher level (15/25 units/g of wet skin) to obtain gelatin of industrial grade with high yield.

Highlights

Chomarat et al [7] reported that treatment of collagen with pepsin under non-denaturing conditions had little effect on the native triple helical structure of collagen and proteolytic pepsin acts on the intraand intermolecular cross links present at the non-collagenous terminal ends and thereby convert the non-soluble collagen into a soluble form [17]
Increasing level of pepsin from 5 to 25 units per gram of wet bovine skin led to increase in gelatin recovery from 18.17 to 24.67%
The gel strength and viscosity decreased, and turbidity increased as the pepsin level was enhanced

Summary

Introduction

Gelatin is animal source biopolymer [1] protein extracted from collagen by partially hydrolyzing it. Collagen is made up of tightly wound triple α helix protein polypeptide chains with molecular weight around 330 kDa, whereas gelatin is a mixture of denatured shorter polypeptide chains exhibiting approximate molecular weight of more than 30 kDa [2]. Various intra- and intermolecular bonds present in collagen make it resistant to acid and heat for conversion into gelatin [3], leading to low gelatin extraction yield [4]. Proteolytic enzymes could aid in the better recovery of gelatin from collagen [4,5,6]. Research has reported gelatin with higher yield with desired rheological and functional properties could be obtained by utilizing proteolytic enzymes

Methods

Results

Conclusion