High Hydrostatic Pressure Treatment of Whole Rice Grains to Enhance the Value of Gluten-Free Flours: Effects on Nutritional, Functional, and Antioxidant Properties

Abstract Refined rice flour is widely used in gluten-free (GF) food formulations due to its suitable sensory attributes. However, its limited techno-functional and nutritional properties make it advisable to implement various technological solutions to improve the quality of the final products. Non-thermal processing technologies, such as high hydrostatic pressure (HHP), are promising strategies to functionalise flours, enhancing their suitability for GF applications. To date, studies aimed at investigating the application of HHP to promote modifications in the functional properties of cereals and cereal products have been scarce and mainly focussed on HHP direct application on basic matrices, such as starches and refined flours. Alternatively, the present study investigated the effects of the combined treatment of pre-soaking and HHP (600 MPa/5, 15, and 30 min of holding time) on whole rice grains to optimise the techno-functional and nutritional properties of the resulting brown rice flours. Flours obtained from the combined treatments exhibited a significant ( p < 0.05) increase in water absorption capacity, while emulsifying activity decreased as holding time increased. The levels of bioactive compounds, particularly thiamine and total phenolic content, were significantly ( p < 0.05) increased in flours treated with the combined pre-soaking and HHP process. Furthermore, flours produced through pre-soaking followed by extended HHP treatment (15 and 30 min) demonstrated significantly higher ( p < 0.05) antioxidant capacity compared with untreated flour and the remaining samples analysed. The findings of the present study suggest that HHP treatment on a whole-grain matrix is an efficient strategy for the production of gluten-free whole-grain flour, resulting in an ingredient with favourable techno-functional properties and enhanced nutritional characteristics.