Effect of Enzymatic Hydrolysis of Brewer’s Spent Grain on Bioactivity, Techno-Functional Properties, and Nutritional Value When Added to a Bread Formulation

The interesting nutritional value and abundance of brewer’s spent grain (BSG) may be adequate for its use as a sustainable functional ingredient. The aim of the present work was to enhance the BSG bioactive properties, along with studying the BSG bread technological feasibility through rheological properties evaluation. To optimize the release of BSG bioactive compounds, enzymatic hydrolysis was carried out using a composite central design, varying the alcalase and cellulase percentage. Multiple regression (MR) and response surface methodology (RSM) were performed, evaluating the total polyphenol content (TPC), ABTS, and ORAC as response variables, showing a positive effect for alcalase % and non-significant effect for cellulase %. Optimal conditions (0.1% alcalase) were used for BSG flour (FBSG) for the development of the functional bread (FBSG bread), substituting 20% w/w wheat flour. The nutritional and bioactive characterization of the breads showed that the FBSG bread presented a higher fiber content (>6%), TPC, and antioxidant activity than the control bread (CB). The breads’ physicochemical characteristics were analyzed by measuring the parameters of volume, color, and texture. Regarding volume, the FBSG bread presented a significant decrease (p < 0.05) (1890.4 ± 6.9 cm3) with respect to CB (2359.5 ± 106.5 cm3), and also presented a significant increase (p < 0.05) in the development of brown/reddish tones in the crumb, which were reflected in the “L” and “a” parameters (53.62 and 6.10, respectively) compared to CB (75.70 and −0.16, respectively). The texture analysis showed that FBSG bread chewiness (6.85 ± 0.13 Kg) and cohesiveness (0.608 ± 0.027) did not present significant differences (p < 0.05) with CB. On the other hand, the FBSG bread parameters of resilience (27.5 ± 2.3), and rubberiness (7.63 ± 0.16 Kg·m·s−2) were increased, while elasticity (89.81 ± 0.067) decreased. In conclusion, a sustainable “high fiber content” and antioxidant bread was obtained presenting suitable rheological properties as that of wheat flour bread. Further studies on the sensory profile and acceptability of the novel food should be addressed to evaluate the consumers’ perception of the rheological parameters