Valorization of Brewer’s Spent Grain Liquid Fraction for the Development of a Pasteurized Strawberry-Based Blend Juice

Brewer's spent grain (BSG) is a high-moisture (70-80%) by-product of the brewing industry. During dewatering, it yields a liquid fraction that can be combined with strawberry pulp (SP) to create a new food product. This study evaluated the use of BSG liquid fraction as a dilution medium for SP to develop a novel blend juice (BJ) and assess its shelf-life after pasteurization. The optimal formulation consisted of 70% BSG liquid fraction and 30% SP, pasteurized at 95 °C for 5 min (BJ5) and 10 min (BJ10), and stored for 8 weeks at 25 °C. Compared to BJ, pasteurization (BJ5 and BJ10) caused significant (<i>p</i> < 0.05) changes in moisture, color (Δ<i>E</i>), soluble solids, and aerobic mesophilic bacteria. Both BJ5 and BJ10 showed sensory attributes, overall acceptance, and purchase intent comparable to two commercial Chilean blend juices. During the 8-week storage, both pasteurization conditions ensured microbiological stability, while color and other chemical parameters remained stable. Nonetheless, moisture, soluble solids, pH, and total polyphenol content were significantly affected (<i>p</i> < 0.05). Overall, the BSG liquid fraction can be successfully repurposed to create a microbiologically stable, sensorially appealing strawberry blend juice with strong potential for the food and gastronomy industries.