| Abstract [eng] |
Featured Application: The bioprocessed wheat bran obtained via combined extrusion and microbial fermentation can be directly utilised as a functional, nutrient-dense ingredient in the food industry. Specifically, it can be incorporated into baked goods, such as high-fibre breads and biscuits, at substitution levels of 5–15% (w/w) for refined flour, or up to 20% in functional snacks and meat analogues. At these levels, the ingredient enhances the nutritional profile by increasing soluble dietary fibre content and improving the in vitro digestibility of the gluten protein fractions. Concurrently, it may optimise processing and techno-functional properties: the disrupted cellular structure and thermo-responsive thickening behaviour of the modified bran have been shown to enhance water-binding capacity and gas retention in doughs, thereby potentially mitigating the typical loaf volume reduction associated with raw bran, while supporting a stable viscosity matrix during thermal food processing. This study aimed to investigate the effects of thermo-mechanical treatment and solid-state fermentation (SSF) on the structural, physicochemical, and techno-functional characteristics of wheat bran (WB), with a particular emphasis on specific isolated protein fractions, starch, and dietary fibre. WB was subjected to extrusion at different temperatures (90, 115, and 130 °C) and screw speeds (16 and 25 rpm), followed by a 24-h SSF with Liquorilactobacillus uvarum. Changes in chemical composition, hydration properties (water absorption, solubility, swelling capacity), temperature-dependent (30–80 °C) extract viscosity, as well as protein extraction yields and in vitro protein digestibility of isolated protein fractions were systematically evaluated. Extrusion reduced insoluble dietary fibre (IDF) content by 15.7–33.9%, while increasing soluble dietary fibre (SDF) content by 59.1–94.2%, and SSF with L. uvarum additionally increased the SDF fraction by 6.5–7.9%. Regarding technological properties, extrusion increased WB water solubility (WS) up to 14.6%, and 24-h fermentation further enhanced WS, reaching up to 16.3%. Extrusion increased the degree of starch gelatinisation up to 49.1%, whereas fermentation reduced it to 40.7% and decreased the WB extract viscosity by 18.3–24.6%. Furthermore, 24-h SSF enhanced the in vitro digestibility of globulin, gliadin, and glutenin fractions from initial values of 71.3–78.8%, 70.6–75.2%, and 70.2–73.0% to 82.0–85.6%, 83.3–88.6%, and 79.4–89.0%, respectively. The observed thermo-induced thickening and enhanced digestibility suggest that modified wheat bran has potential as a functional bio-ingredient for future application in novel food formulations. |
