author(s)
KG Baraiya, CV Raju, Vijay Kumar Reddy Surasani, IP Lakshmisha and P Arun Kumar

abstract
Pacu processing waste was used to recuperate proteins from it using pH shift process, followed by the quantification and detailed characterization of recovered Pacu protein isolates. Maximum protein solubility was recorded at pH 2.0 (16.13 ± 0.30 mg/ml) and pH 12.0 (14.67 ± 0.26 mg/ml), with a total process recovery of 63.49 ± 0.36 and 53.53 ± 0.21%, respectively. Process variables showed significant effect of protein solubility and recovery yields (p<0.05). Maximum solubility was reported with the extraction time of 60 min at 50^oC, weight to extractant volume ratio of 1:3, centrifugation speed of 8000 rpm and continuous stirring condition. Alkaline processed isolate had higher protein content (22.87 ± 0.74%) than acidic processed isolates (21.01 ± 0.88%). The protein isolate obtained through acidic/alkaline aided processing had a reduced level of total lipid, myoglobin and pigments as compared to the raw material. Foaming capacity was higher in acidic aided protein isolate than in alkaline based protein isolate, whereas foaming stability, water holding capacity and emulsion capacity were higher in alkaline processed isolate than acid processed isolates (p<0.05). Proteins recovered from Pacu fish by acid/alkali solubilisation method showed good yields and functional properties. The alkaline aided protein isolation was proved to be better in terms of protein yield as well as quality of isolates. The recovered proteins showed higher protein concentrate, gelling and texture properties as well as good amino acid profile.