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High pressure processing at different hydration levels as a tool to enhance rice bran stability and techno-functionality

Abstract:

High-pressure processing (HPP) enhances food safety and shelf life by inactivating microorganisms and preserving food quality, yet its effectiveness in low-humidity environments has not been evaluated. This study investigated the effects of HPP at 500 MPa for 15 min across varying hydration levels (15, 30, 60, 77 %) on rice bran (RB), aiming to identify microbial effectiveness, besides techno-functional and physicochemical properties. HPP effectively reduced mesophilic bacteria, molds and yeast of RB at > 15 % hydration level, achieving reductions of up to 4 logarithmic cycles in the latter, nearing the detection limit of the method. However, it did not significantly impact spore inactivation. HPP treatment of ≥ 30 % hydrated RB induced particles aggregation and a honeycomb formation. The interaction between hydration and HPP treatment significantly affected the distribution of total dietary fibers, with an increase in soluble dietary fiber from 8.73 g/100 g to 11.03 g/100 g after HPP treatment at 15 % hydration level. Protein solubility was enhanced by hydration (15, 30 and 60 %), and peroxide values decreased after HPP treatment at low hydration (≤30 %) but increased when applied to high hydrated (>30 %) RB. Emulsifying activity decreased upon HPP treatment of highly hydrated RB (≥60 %), but more stable emulsions were achieved after HPP, regardless of the hydration level. Therefore, this study highlights the potential of HPP as a sustainable approach to enhance the utilization of rice bran in food applications, addressing existing knowledge gaps regarding its processing under different moisture conditions.