- An emerging strategy to reducing food waste is converting food processing byproducts to nutritious and inexpensive food ingredients. A relevant food processing waste stream is brewers’ spent grain (BSG), the primary byproduct of beer production. BSG is a promising candidate as a food ingredient because of its high protein and fiber content, but it must be stored properly and dried sufficiently to prevent microbial spoilage. In this study, the effects of four storage conditions (Never Stored, Frozen (-20°C), Fridge (2°C), 16°C) and two drying conditions (HT: High Temperature, 65°C, 20% RH and LT: Low Temperature, 40°C, 50% RH) on the drying and hydration of BSG were analyzed through the determination of moisture sorption isotherms (MSIs). MSIs were determined by the climate box method and produced type-II sigmoidal curves. The MSIs for the Never-Stored BSG was similar for HT and LT drying, but for the three stored samples, LT-dried BSG absorbed more water in the aw = 0.2-0.5 region. This implies that LT drying affected the capturing tendency of the BSG in terms of porosity and/or surface chemistry. These results provide insight on the hydration properties of oven-dried high-fiber food byproducts and discuss important experimental considerations of MSI determination.