Emulsifying properties of some legume proteins

Protein concentrates of some Nigerian underused legume seed flours, lima bean ( Phaseolus lunatus L.) and pigeon pea ( Cajanus cajan ), were prepared by alkaline extraction followed by acid precipitation, whereas that of African yam bean ( Sphenotilis sternocarpa ) was prepared by acid extraction followed by alkaline precipitation. Simple and objective means that allowed precise determination of the inversion point were used in investigating the capacity of the protein concentrates to emulsify fat. Their relative efficiencies as emulsion stabilizers were also investigated. The results revealed that the emulsifying capacities of these protein concentrates decreased with increasing protein concentration and emulsifying speed. However, emulsifying capacities increased with increasing initial aliquot size, whereas variation of speed of oil addition did not have any significant influence. The capacity of the protein concentrates to emulsify fat decreased in the order pigeon pea protein concentrate > lima bean protein concentrate > African yam bean protein concentrate. But for emulsion stability, the protein concentrates were in the opposite rank order.