Protein Quality, Secondary Structure and Effect of Physicochemical Factors on Emulsifying Properties of Irvingia gabonensis Almonds

Abstract

Background: There is a constant search of new plant proteins, with adequate nutritional and functional properties, as well as bioactive properties and low-cost for utilization in various food formulations. Objective: The aim of this work was to access the nutritional and functional potential of protein from Irvingia gabonensis, for utilization as ingredient or supplement in food. Methods: Proximate composition and amino acid were analyzed. Nutritional parameters were calculated from amino acid composition. Physicochemical properties and secondary structure of protein were determined. Finally, effect of oil to water ratio (OWR), pH and concentration on emulsifying properties was analyzed. Results: The flour contained 22.26% protein, 5.30% ash and 60% carbohydrates. Proteins contained all essential amino acids, with high content of Leu, Ile, Val, Thr and sulfur-containing amino acids. Essential amino acid index (69%), protein efficiency ratio (2.39-2.63) and biological value (79.91%) were studied. The maximum protein solubility (61%) was noticed at pH 8, while high hydrophobicity was observed at pH 2. A transition from an irregular secondary structure to a more ordered structure was found from pH 2-4 to pH 6-10. pH, OWR and concentration significantly affected emulsifying properties of Irvingia gabonensis almonds. The maximum emulsifying capacity (EC) was observed under acidic pH and high flour concentration. EC increased with increasing OWR and concentration, while decreased with increasing pH. High ES (25-35%) was observed at pH 4-8 and OWR of 1/3 to 1/2 (v/v), at flour concentration of 3-4% (w/v). Conclusion: Irvingia gabonensis showed good potential as food ingredient or supplement.