Unveiling the effects of cold plasma treatment on the structural, rheological, and functional properties of rice bean protein isolate

Abstract

In the present study, the impact of cold plasma treatment (CPT) on rice bean protein isolate (RBPI) was systematically investigated to evaluate its functional and structural modifications. Unlike previous CPT studies, which primarily focused on soy, pea, or wheat proteins, this work explores rice bean protein—a nutritionally rich but underutilized legume source—with the aim of enhancing its techno-functional qualities for food applications. The untreated RBPI (sample A) was subjected to CPT under varied treatment intensities, and the optimal condition was identified based on the greatest improvement across multiple functional and structural parameters. Notably, sample F (20 kV for 10 minutes) exhibited the most significant enhancements. Among all treatments, the optimally modified sample exhibited major improvements, including increases in protein solubility from 71.95% to 88.13%, foaming capacity from 33.3% to 300%, emulsifying activity from 30% to 58%, and water-binding capacity from 2.09 g g⁻¹ to 2.94 g g⁻¹. Scanning electron microscopy (SEM) showed greater surface porosity and particle fragmentation, while Fourier transform infrared (FTIR) spectroscopy confirmed alterations in secondary structure, particularly enhanced β-sheet content. Rheological analysis demonstrated improved viscoelasticity and gel strength, and SDS-PAGE verified that CPT altered conformation without affecting molecular integrity. ANOVA and DMRT statistical analysis revealed significant improvements (p < 0.01) in both functional and structural attributes in the treated samples compared to the untreated ones. Collectively, these results underscore the potential of cold plasma treatment as a viable approach for improving the structural and functional properties of rice bean protein isolate.