Valorization of pulp and viscera from hybrid sorubim and pacu by production of protein concentrate using alkaline solubilization

Abstract

Fish protein concentration (FPC) by alkaline solubilization has proven to be an alternative method in adding value to muscle-based materials. The aim of this work was to evaluate the influence of different processes (decanting/sieving or centrifugation), reagents (sodium bicarbonate or sodium hydroxide) and washing cycles (1–4) on the quality of protein concentrates obtained from mechanically separated meat (MSM) and viscera of hybrid sorubim (Pseudoplatystoma reticulatum × P. corruscans) and pacu (Piaractus mesopotamicus) fishes. The protein concentrate was obtained by washing the viscera or MSM during up to four cycles (4:1 solution:meat ratio). In each cycle, the liquid waste and fat were removed by decanting/sieving or centrifugation. Moisture, crude protein, crude fat and crude ash contents were determined after each washing cycle. The moisture and protein contents increased immediately after the first washing up to 77.88% (dry basis). The lipid content decreased with the cycles down to 2.99% (dry basis). Higher FPC yield was obtained for MSM during the centrifugation process compared to the decantation/sieving process. Two weight yields above 100% were found in procedures with NaHCO₃ and MSM of hybrid sorubim and pacu, probably due to the larger capacity of gel formation during protein concentration. Differences related to the fish species were more evident than the processes and utilized reagents.