Effect of High Pressure Processing on the quality of protein isolates extracted from shrimp head waste during refrigerated storage

Abstract

Effect of high pressure treatment on physico-chemical and microbiological quality of protein isolates from shrimp head waste was evaluated. Protein isolates were prepared using alkali solubilisation and isoelectric point precipitation. Protein isolates were subjected to high pressure treatment at 200 and 400 M Pa with a holding time of 10 min at 30 plus or minus 3 degree celsius and the samples were designated as S-200 and S-400. Untreated samples were designated as control. The three groups were stored at 2 plus or minus 1 degree celsius for shelf life evaluation. Biochemical analysis such as TVB-N, TBARS and TMA showed increasing trend during storage. The values obtained for biochemical quality indicators were higher than the acceptable limit for control on 21st day of storage, whereas S-200 was unacceptable by 35th day. The S-400 was within the acceptable range even after 35 days of storage as revealed by biochemical analysis. The observed changes in biochemical quality parameters were well related with the APC. The coliforms were detected in control and S-200 samples on 28th day, whereas, the coliforms were not detected in S-400 throughout the storage study period. Enterobacteriaceae count of Control and S-200 increased, whereas, S- 400 sample was free from enterobacteriaceae during the storage. Whiteness (L) values of protein isolates increased with increase in pressure level. However, L values was decreased as storage period increased in all the samples. The results revealed that the high pressure treatment at 400 MPa with a holding time of 10 min extended the shelf life of protein isolates by 14 days under refrigerated storage over the untreated sample.