Valorization of brewer's spent grains through Ganoderma lucidum cultivation: Functional food ingredients and bread prototypes

Brewer spent grain (BSG) is the primary by-product of beer production, representing 85% of total waste in this industry. This study aimed to valorize BSG by incorporating it into the cultivation medium for Ganoderma lucidum to develop functional food ingredients with enhanced techno-functional and nutritional properties, particularly focusing on fiber and protein content. The following four samples were analyzed: (1) 100% BSG, (2) 50% BSG and 50% commercial fungal medium (Mix), (3) lyophilized biomass of G. lucidum, and (4) oven-dried biomass of G. lucidum (OGB). BSG had the highest fat (6.17 +/- 0.26 g center dot 100 g(-1)db), protein (19.66 +/- 0.80 g center dot 100g(-1)db), soluble dietary fiber (15.87 +/- 0.76 g center dot 100g(-1)db) and carbohydrate levels (29.99 +/- 0.60g center dot 100 g(-1)db). The Mix demonstrated the highest total fiber content (70.02 +/- 0.62 g center dot 100 g(-1)db) and insoluble dietary fiber (63.15 +/- 0.71 g center dot 100 g(-1)db). Four prototypes were created by partially substituting wheat flour with different percentages of BSG and OGB in traditional bread recipes. A 7-point hedonic scale assessed appearance, odor, texture, and taste, and a 5-point Likert scale rated overall acceptance. Samples A1 and B2 had the highest scores across hedonic attributes (>6). B2 excelled in overall acceptance (4.36), while D2 scored the lowest (2.89) due to its bitter taste, most likely derived from the presence of fungal triterpenoids.