Effect of Different Papain Concentrations on the Properties of Chicken Skin Protein Hydrolysates

Abstract

Chicken skin is a source of animal protein hydrolysate, which has a potential as an antioxidant. This study aimed to determine the effect of different concentrations of the enzyme papain on the degree of hydrolysis, antioxidant capacity, percentage of reducing power (%RP) and amino acid composition of chicken skin protein hydrolysate. Hydrolysis was carried out using papain with various concentrations (3%, 4% and 5%, w/w protein substrate) at pH 7 and 50℃ for 6 h. The degree of hydrolysis was determined by spectrophotometry. Antioxidant capacity and %RP was determined by ferric reducing antioxidant power method and expressed in milligram of ascorbic acid equivalent per gram of sample, and amino acid composition were determined using high-performance liquid chromatography. The results showed that variations in papain concentration had a significant effect (P<0.05) on the degree of hydrolysis, antioxidant capacity and %RP of chicken skin hydrolysate. The papain concentration of 4% resulted in the optimum protein hydrolysate with a degree of hydrolysis of 61.68%±0.64%, an antioxidant capacity of 8.72±0.30 mg AA/g sample and a %RP of 54.12%±1.78%. The protein hydrolysates of the treated chicken skin showed a high content of amino acids, namely, glycine, glutamate, proline, arginine and aspartate.