STRUCTURAL MODIFICATIONS IN COMMON BEAN (PHASEOLUS VULGARIS L.) PROTEINS INDUCED BY LOW-PRESSURE OZONE TREATMENT

The growing demand for economically viable plant-based proteins with suitable structural and techno-functional properties has intensified research into alternative protein sources. This trend is driven by global population growth and the increasing adoption of diets free from animal-derived ingredients. In this context, non-conventional technologies such as ozone treatment have emerged as promising strategies to modify and enhance the properties of legume proteins, particularly those from common bean (Phaseolus vulgaris L.). This study aimed to evaluate the structural properties of bean protein concentrate subjected to low-pressure ozone treatment. For the experiments, 5.0 kg of beans were exposed to ozone in a hypobaric chamber (70 L) until the internal pressure reached 100,000 Pa. Ozone was applied at a concentration of 61.37 mg L⁻¹ and a flow rate of 1.0 L min⁻¹ across ten injection cycles. Untreated sample served as the control. The grains were ground using an industrial blender (18,000 rpm/5 min) and subjected to alkaline extraction (1:10 flour-to-water ratio, w/w, pH 10), followed by isoelectric precipitation (pH 4.5) and freeze-drying. Protein samples were dispersed in sodium phosphate buffer (0.1 N, pH 7) and analyzed for zeta potential, particle size, polydispersity index, and intrinsic fluorescence. No significant differences were observed in zeta potential (~81.50 mV) and polydispersity index (~0.50) between treated and untreated samples (p>0.05). However, ozone treatment increased particle size by 11.60% (p<0.05), likely due to the partial protein denaturation and subsequent aggregation of hydrophobic regions, driven by minimization of Gibbs free energy. This structural modification was supported by a significant increase in fluorescence intensity (2063.50 ± 43.23) compared to the control (1684.87 ± 260.54),attributed to the greater exposure of tryptophan residues and oxidative changes induced by ozone. These findings indicate that low-pressure ozone treatment can induce relevant conformational changes in bean proteins, potentially enhancingtheir techno-functional properties and broadening their applications in the food industry.