ABSTRACT Research on the processing of organic solid waste has expanded considerably in recent years. Brewer's spent grain (BSG) is the main by‐product of the brewing industry, representing around 85% of the total by‐products generated. Although it has traditionally been used as animal feed, spent grain is increasingly incorporated into various food products due to its high nutritional value, making it a promising protein and energy source for human nutrition. For such use, it must be dried to reduce its mass and increase its shelf life. In this study, BSG samples were dried by using different drying methods (hot air (tray) drying, microwave drying, infrared drying, and freeze drying) and drying kinetics were investigated. Moreover, the utilization of BSG powder as a functional ingredient in bread and cake formulations was evaluated according to the physical and sensorial properties of these bakery products. Drying kinetics fitted best to the Midilli et al. model ( R 2 > 0.99). Microwave drying achieved the shortest drying time (25 min), the highest total phenolic content retention (2.17 mg GAE/g dm), and produced bakery products with the highest specific volume and porosity, along with superior sensory scores. Freeze‐dried BSG showed the highest protein content (19%) and water‐holding capacity (6.40 g/g), while microwave‐ and infrared‐dried samples also exhibited similarly high protein levels; in contrast, hot air drying resulted in the lowest protein content and the greatest color change. Incorporation of BSG flour increased protein (up to 8.75% in bread), dietary fiber (up to 13.30% in bread), and fat content compared to controls, improving nutritional value without compromising consumer acceptability. The results emphasize that drying, as a pre‐handling step, significantly influences the quality attributes of BSG and its performance in food systems, independent of variations in raw material composition.
Yılmaz et al. (Fri,) studied this question.