Physicochemical and Functional Properties of Protein Isolate from Ackee (Blighia sapida) Seed

Abstract

Ackee seeds are a major waste of the ackee canning industry. The seeds bio-accumulate the toxin hypoglycin but are also a potential source of protein. The objective of this study was to produce a protein isolate from the ackee seed and determine the chemical and functional properties of the isolate. Proteins were extracted from the defatted ackee seed flour using sodium borate buffer (pH 10.0, 50 mM) and aqueous ethanol (75% v/v). The protein isolate was then dried under vacuum and milled into a powder. The ackee seed protein isolate contained low molecular weight proteins comprising principally glutamic acid, arginine, glycine and aspartic acid with hypoglycin content within regulatory limits. Ackee seed protein powder, in comparison to soy protein isolate, demonstrated high solubility, formed stable emulsions and demonstrated good foaming properties, particularly at acidic pH values, making it suitable for use in acidic foods such as fruit juices, beverages and yoghurts. The purity (g protein/100 g isolate) of the ackee seed protein isolate was found to be lower than that of the commercial soybean protein isolate while higher quantities of fat and ash were present in the soybean protein isolate. The water and oil absorption capacities (g/g isolate) of ackee seed protein were lower than those of the commercial soybean protein isolate. Hypoglycin content in the ackee seed protein isolate was determined to be below the commercial standard for ackee products.