Unlocking the potential of rice bran through extrusion: a systematic review†

Rice bran (RB) is a by-product of the rice milling process and is rich in nutrients and bioactive compounds making it a valuable ingredient for extruded foods. Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) was applied that involved screening large databases (Google Scholar, PubMed, Web of Science, ScienceDirect and Scopus) and analysing the most relevant peer-reviewed forty-four journal articles. This review discusses the benefits of incorporating RB into various food product formulations, including meat analogues, biscuits, cookies, cakes, noodles, breads, and pasta. The review also examines how extrusion conditions, such as temperature, screw speed, and moisture content affect the physicochemical parameters of the expanded extrudates from the feed formulation incorporated with RB. In extrusion, 0–30% RB was used as feed in 52.27% of the studies, and 71.42% of the studies used screw speed below 250 rpm. Almost all studies had extrusion temperatures below 150 °C, and plant-based meat used a higher moisture content (60–70%) during extrusion. The extrusion of RB results in increased hardness and bulk density, and reduced expansion. However, depending on the feed's composition, moisture content, extrusion temperature, and screw speed, its addition to the feed mixture could cause variability of results for the water solubility index (WSI), water absorption index (WAI), thermal behaviour and viscosity. RB in foods processed through extrusion enhances their nutritional profiles, especially total phenolics, antioxidant activity, and functional properties and supports sustainable practices. Overall, the use of RB in food extrusion holds promise for the development of nutritious, functional, and sustainable food products.