Optimization of acid hydrolysis conditions of delimed tannery fleshings by response surface method

摘要

An ecofriendly method, involving mild organic acids to hydrolyse del med tannery fleshings (TF), has been developed. Combination of formic acid and propionic acid (1:1) was employed to obtain hydrolysates with higher degree of hydrolysis (DH). Better antioxidant properties were obtained by response surface method (RSM) using a factorial design. Effect of pretreatment involving steam cooking (80℃ for 15 min) indicated that cooked delimed TF on acid treatment had significantly (P<0.5) higher protein extractability than uncooked delimed TF. Optimized levels of factors for obtaining highest DH (>51 %) at room temperature for cooked delimed TF were acid mixture (20%) and incubation time (9 days). Liquid hydrolysate from TFs exhibited antioxidant activity (125.56 μg ascorbic acid equivalents /ml extract) and diphenyl picrylhydrazyl (DPPH) radical scavanging activity (46.42%). Chemical score of hydrolysate revealed an excess amount of essential amino acids (arginine, leucine and lysine) as compared to reference protein. This indicates its potential for use in livestock/aquaculture feeds.