Recovery and characterization of Balanites aegyptiaca Del. kernel proteins. Effect of defatting, air classification, wet sieving and aqueous ethanol treatment on solubility, digestibility, amino acid composition and sapogenin content

In order to find alternative protein sources in African regions where prote in deficiency in nutrition is prevailing, solubility, in-vitro digestibilit y, amino acid composition and chemical score of Balanites aegyptiaca Del. k ernel proteins were investigated as a function of different processing step s including defatting, air classification, wet sieving and aqueous ethanol treatment. Air classification delivered a fine fraction of 58.1% of the tot al protein. Applying a wet sieving process, a protein concentrate of 72.9% protein content was achieved but the recovery was very low (35.6%). However , in case of isoelectric precipitation followed by aqueous ethanol treatmen t both protein content (78.2%) and recovery (53.7%) were high. Data concern ing the chemical score revealed, that lysine content of the defatted kernel flour amounted to 74.2% of the recommended FAO/WHO standard level. In-vitr o protein digestibility was found to be higher than of legume proteins. The digestible protein of the full fat flour, defatted flour, air classified a nd wet sieved fine fractions and protein concentrate were 91.9, 93.7, 82.0, 86.4 and 94.2%, respectively. The sapogenin content per 100 g protein of t he investigated protein preparations was significantly lower (46% to 62%) t han of the initial material (oilcake).