Enzymatic and microbial valorization of lignocellulosic biomass for food applications

Abstract

Meeting the increasing global food demand requires innovative production strategies using sustainable technologies, including biocatalysis and microbial technology. The long-term viability of any such strategy, however, depends on access to affordable and renewable feedstocks. The sustainable production of novel foods and food ingredients from lignocellulosic biomass (LCB), particularly from agrifood side streams, offers an attractive strategy to enhance both waste management and food security, simultaneously. LCB, the most abundant renewable material on earth, represents a promising sugar-rich feedstock. Regardless of origin, LCB are composed of three main components: cellulose, hemicellulose, and lignin, though their proportions vary depending on the source. Due to its high sugar content, LCB is widely regarded as a promising renewable carbon source for microbial fermentation, with potential applications in food industries. However, polysaccharides in LCB are not readily hydrolysable to supply fermentable sugars essential for microbial growth, as they form a complex, interconnected network with lignin. In addition to physical and chemical methods, enzymes and microorganisms are extensively used in LCB valorization processes, for biomass pre-treatment, hydrolysis, and fermentation. The production of several important food ingredients, such as single-cell proteins, microbial oils, dietary fibers, vitamins, and organic acids, has been demonstrated through the biological conversion of LCB. Isolated ligninolytic and polysaccharolytic enzymes, enzyme cocktails, microbial secretomes, isolated bacteria and fungi, and natural and synthetic microbial consortia have been studied for this purpose. This review discusses recent advances in microbial and enzymatic valorization of agrifood-derived LCB for food-related applications. We specifically highlight the composition of major lignocellulosic sidestreams and biobased tools and techniques used for their conversion into food ingredients, with a special reference to enzymatic and microbial technologies. Furthermore, we discussed current challenges and prospects of LCB valorization for food applications via biological routes.