Recovery of emulsifying and gelling protein from waste chicken exudate by using a sustainable pH-shifting treatment

The inevitably generated chicken exudate was usually unconsciously discarded, leading to protein waste and environmental pollution. The study is performed to reveal the loss and constitute of different sourced exudate (purge exudate/defrozen exudate, PE/DE), investigate the efficiency of various pH-shifting strategies (Method I: NaOH-HCl, Method II: Ca(OH)2-Critric acid, and Method III: Ca(OH)2-Glucono δ-lactone) in recovering selected exudate, and evaluate the functionality of these recovered protein isolates. Accordingly, PE and DE shared greatly similar (P > 0.05) lipid and ash content. Despite sarcoplasmic protein, there are a small amount of functional myofibrillar protein in the exudate samples. During extraction, Method III had higher recovery yield (85.5%) than other two groups, but the isolates contained higher level of moisture. The protein isolates treated with Method II exhibited highest emulsion ability, while the Method III treated group obtained best gelation properties. Overall, pH-shifting could recover functional protein from chicken exudate for industrial application.