Nutritional composition and techno-functional properties of sago palm weevil (Rhynchophorus ferrugineus) larvae protein extract

Abstract

The present study investigated nutritional composition and techno-functional properties of Rhynchophorus ferrugineus larvae (sago grubs) protein extract (SGPE). The fat, carbohydrate, and protein contents of sago grubs were 58.79 %, 18.67 %, and 15.65 %, respectively. SGPE exhibited an isoelectric pH of ∼ 4 based on alkaline solubilisation and pH precipitation. Total essential amino acid (EAA) content and essential amino acid index (EAAI) of SGPE were 223.2 mg/g protein and 0.84 respectively. SDS-PAGE of SGPE displayed proteins in the 10–110 kDa molecular weight range, with substantial protein bands < 20 kDa. As expected for a protein extract, FTIR analysis of SGPE indicated five distinct regions (amides I, II, III, and amide A and B peaks). Techno-functional analysis of SGPE indicated a high foaming capacity (87.3 %) and emulsion stability (96.8 % after 60 min). Heat coagulation of SGPE was higher at pH 7.0 (19.5 %) than that at the pI of 4.0 (4.83 %), corroborating the pH-solubility profile, and relatively high surface hydrophobicity (294.5). The heat enthalpy of the SGPE (59.8 J/g) was lower than that reported for H. illucens and A. cordifera. These findings demonstrate the suitability of SGPE for food technology applications in relation to to the reported techno-functional properties and amino acid profiles.