Characterisation of pH-shift-produced protein isolates from sago palm weevil (Rhynchophorus ferrugineus) larvae

Abstract

Farm-raised sago palm weevil (Rhynchophorus ferrugineus) larvae (SPWL) can be used as a protein source for food sustainability. This study aimed to investigate the potential of pH-shift processing as a cold refinery approach to produce protein isolate from SPWL. Maximum solubility of SPWL protein was observed at pH 2.0 (acid-aided process) and pH 11.5 (alkaline-aided process). The zeta-potential of the protein solution was close to zero with the lowest solubility at pH 4.5. So, the protein precipitation was performed at this pH. Although both acid and alkaline methods yielded roughly 66% protein, their nutritional and techno-functional features differed based on the pH-shifting process. The alkaline-produced protein isolate had higher essential amino acid (EAA) content and EAA index but it was darker in colour. The acid-produced protein isolate had larger levels of umami-taste-active and functional amino acids, as well as a higher emulsifying capability.