Swedish Centre for Resource Recovery, University of Borås, 50190 Borås, Sweden.
Swedish Centre for Resource Recovery, University of Borås, 50190 Borås, Sweden.
Waste Manag. 2023 Sep 1;169:382-391. doi: 10.1016/j.wasman.2023.07.021. Epub 2023 Jul 31.
Brewer's spent grain (BSG) is a clean byproduct from the food sector, comprising 85% of the brewing process solid byproducts. BSG is mainly used as low-quality animal feed and often ends up in landfills due to its short shelf life. However, considering its abundant availability and high nutritional content, BSG holds the potential for biorefineries to produce valuable products. The recalcitrant nature of BSG poses a challenge, requiring pretreatment steps. Therefore, this study focused on valorizing BSG obtained from organosolv pretreatment by producing food- and feed-grade single-cell protein (SCP). The BSG was subject to organosolv pretreatment at 180C for 2 h with 50% v/v ethanol as solvent. Filamentous fungi N. intermedia and A. oryzae were cultivated on as-received and different fractions of organosolv-treated BSG to evaluate the effect of factors such as pretreatment, fungal strain, pretreated fraction content, and substrate loading on fungal biomass yield, biomass composition (protein content), and metabolite production. A. oryzae cultivation on all tested substrates yielded 7%-40% more biomass than N. intermedia. Cultivating A. oryzae on organosolv liquor resulted in the highest biomass protein content (44.8% ± 0.7%) with a fungal biomass concentration of 5.1 g/L. A three-fold increase in the substrate loading increased the ethanol-to-substrate yield by 50%, while protein content was decreased by 23%. Finally, a biorefinery concept was proposed to integrate the organosolv pretreatment of BSG with fungal cultivation for maximum yield of SCP while obtaining other products such as lignin and ethanol, providing a sustainable rout for managing BSG.
啤酒糟（BSG）是食品行业的一种清洁副产物，占酿造过程固体副产物的 85%。BSG 主要用作低质量的动物饲料，由于保质期短，往往最终被填埋。然而，考虑到其丰富的可用性和高营养价值，BSG 为生物精炼厂生产有价值的产品提供了潜力。BSG 的顽固性构成了挑战，需要进行预处理步骤。因此，本研究专注于通过生产食品和饲料级单细胞蛋白（SCP）来利用从有机溶剂预处理中获得的 BSG。BSG 在 180°C 下用 50%（v/v）乙醇作为溶剂进行有机溶剂预处理 2 小时。丝状真菌 N. intermedia 和 A. oryzae 在收到的和不同部分的有机溶剂处理的 BSG 上进行培养，以评估预处理、真菌菌株、预处理部分含量和基质负荷等因素对真菌生物量产量、生物质组成（蛋白质含量）和代谢产物产生的影响。与 N. intermedia 相比，A. oryzae 在所有测试的基质上培养可产生 7%-40%更多的生物量。在所有测试的基质上培养 A. oryzae 可获得最高的生物质蛋白含量（44.8%±0.7%），真菌生物量浓度为 5.1 g/L。基质负荷增加三倍可使乙醇对基质的产率提高 50%，而蛋白质含量降低 23%。最后，提出了一种生物精炼厂概念，将 BSG 的有机溶剂预处理与真菌培养相结合，以在获得木质素和乙醇等其他产品的同时最大程度地提高 SCP 的产量，为管理 BSG 提供了可持续的途径。
