Physicochemical and chemical properties of mung bean protein isolate affected by the isolation procedure

Christina Wintersohle; Inola Kracke; Laura Melanie Ignatzy; Lara Etzbach; Ute Schweiggert-Weisz

doi:10.1016/j.crfs.2023.100582

Physicochemical and chemical properties of mung bean protein isolate affected by the isolation procedure

Curr Res Food Sci. 2023 Aug 29:7:100582. doi: 10.1016/j.crfs.2023.100582. eCollection 2023.

Authors

Christina Wintersohle¹, Inola Kracke¹, Laura Melanie Ignatzy², Lara Etzbach¹, Ute Schweiggert-Weisz^{1

2}

Affiliations

¹ Institute of Nutritional and Food Sciences, Food Sciences, University of Bonn, Meckenheimer Allee 166a, D-53115, Bonn, Germany.
² Fraunhofer Institute for Process Engineering and Packaging, Giggenhauser Straße 35, D-85354, Freising, Germany.

Abstract

The effects of different mung bean protein isolation methods on the chemical composition, the physicochemical properties, and selected antinutritional factors of mung bean protein isolates were investigated. Six protein isolates were prepared by isoelectric precipitation at different extraction pH levels (pH 8 and 9), by micellization, and by hybrid isolation at varying salt concentrations (0.25 M, 0.50 M, 0.75 M). The extraction conditions affected the amount of antinutritive compounds of the isolates. Compared to mung bean flour, micellization reduced phytic acid content by approximately 48% and trypsin inhibitor activity by around 88%. The remaining phytic acid concentration of the isolates influenced their re-solubility, particularly under acidic conditions. The protein isolates exhibited significant differences in surface hydrophobicity and thermal characteristics, indicating structural modifications caused by the extraction methods. Micellization and extraction at pH 8 were identified as mildest isolation methods, as evidenced by the highest enthalpy values. SDS-PAGE analysis demonstrated an enrichment of globulins and comparable protein profiles among the isolates, suggesting that the observed differences arise from conformational changes rather than variations in protein composition. The product yield in protein extraction from mung beans ranged from 8% to 19%, emphasizing the importance of enhancing overall extraction efficiency or exploring the utilization of by-products obtained during the protein isolation process.

Keywords: FT-IR; Isoelectric precipitation; Micellization; Phytic acid; Protein solubility; Protein yield.