Physicochemical and functional properties of Flavourzyme-extracted protein hydrolysate from oil palm leaves

Oil palm industries produce large quantity of wastes, and their limited usage causes major disposal problem in the mills and environmental pollution. Nevertheless, the oil palm leaves (OPL) contain numerous nutritional components especially protein that is applicable to food as a functional ingredient. Thus, this study aimed to extract protein hydrolysate from OPL using Flavourzyme, which is an endo and exopeptidase enzyme derived from Aspergillus oryzae and determine their physicochemical and functional properties including thermal stability, solubility, and emulsifying properties (EP). The FTIR spectral portrayed that the functional groups of OPL were altered after the enzymatic hydrolysis with the presence of a secondary amine. The protein hydrolysate (769-1167 J/g) showed lower enthalpy heat than OPL (7854 J/g). The protein hydrolysate extracted using 0 and 2% Flavourzyme resulted in a high degree of hydrolysis (74-96%) and absolute zeta potential. The hydrolysate also exhibited good solubility (77-97%) and EP in pH 7 and 10 resuspension solutions, showing that it has wide application in food systems. The results signified that the hydrolysis at pH 7 is optimum for the endogenous enzymes present in OPL to hydrolyze peptides with good functional properties, comparable to other plant protein hydrolysate. In summary, the protein hydrolysate extracted from OPL without using enzyme at pH 7 for 2 h of hydrolysis has high protein content, good solubility, and EP, which serves as a potential functional food to improve nutritional value and food properties. Further study on its biological activities recommended for wider application as a functional food.