Functional properties and nutritional quality of acetylated and succinylated mung bean protein isolate

Mung bean protein isolate was acylated to various degrees by acetic and succinic anhydrides. Changes in functional properties (protein solubility index in different solutions, water and oil absorption capacities, emulsification properties, foam capacity and stability), antinutritional factors (tannins, phytic acid and trypsin inhibitor) and in-vitro protein digestibility of acylated protein isolate were determined. The modification rate with acetic anhydride was greater than with succinic anhydride. Succinylation significantly increased the protein solubility index in water and 1 M NaCl whereas acetylation decreased it in water. Acetylation and succinylation caused significant increases in water and oil absorption capacities. Foam capacity and foam stability (up to 0.4 g anhydrides/g protein) were significantly increased due to acylation. Significant increase was observed in emulsification capacity and emulsification stability (up to 0.8 g acetic and 0.6 g succinic anhydrides/g protein) by acylation; however, emulsification activity was significantly decreased over 0.6 g anhydrides/g protein. Acetylation is more effective for reduction of antinutritional factors than succinylation. Also, acetylation is more effective in improving the in-vitro protein digestibility than is succinylation.