Protein Extractability and Thermally Induced Gelation Properties of African Locust Bean Proteins (Parkia biglobosa Jacq. R.Br)

Abstract

African locust bean (AfLB) protein isolates could be an interesting alternative to the use of soy as an ingredient for the development of new protein-rich products. From AfLB seed flour, the protein extractability yields by aqueous extraction were determined as a function of pH and ionic strength. Then thermally induced gelation of various protein suspensions relating to protein concentration was studied. The most critical factors affecting extractability were the pH and the presence of fat. As a function of the extraction process, the extraction yield of protein from AfLB flour ranged from 30 to 65%. Two major fractions of proteins detected in AfLB seeds were albumins and globulins, comprising four families: legume-like protein, vicilin-like proteins, convicilin, and albumins. The globulin isolate had the lowest solubility at pH 3.5-4 and the highest at pH 8-10. The solubility of albumin isolate was lightly affected by pH and ionic strength. At pH 7, the minimum protein concentration for thermal gel formation ranged from 55 to 120 g/L as function purified state of proteins. The less purified extract with a simpler process made it possible to obtain a gel needing a lower protein concentration. This last way seems promising to the development of new foods based on African locust bean flour.