Enhanced Glucan–Chitin Complex Extraction from Deoiled Yeast Biomass for Sustainable Biorefinery Applications

Spent microbial biomass is a major type of carbon and nitrogen-rich by-product generated by bioprocess industries. These spent biomasses, rich in valuable carbohydrates, has remained underutilized due to a limited understanding of their conversion to value products. One such solid by-product stream is carbohydrate-rich (64.56 wt %) de-oiled yeast biomass, a type of spent microbial biomass originating from the oleaginous fermentation process. The present study deals with the enrichment and extraction of the glucan–chitin complex from DYB focusing on scalability with minimal release of chemical load to the environment. The complex obtained through sequential fractionation and hypochlorite-assisted extraction was assessed for its quality and structural characteristics. A glucan–chitin complex enrichment from 4 to 49.22 wt % glucan with a 17.07 wt % chitin was obtained, exhibiting a helical arrangement of β-(1 → 3) and β-(1 → 6) glucan chains linked to chitin via β-(1 → 4) linkage. The results showed that the investigated process could be integrated with the yeast lipid production chain to obtain these quality compounds from its by-product stream. The green chemistry metrics, viz., PMI, atom economy, and optimum efficiency of 23.34 kg/kg, 1.41, and 8.36, indicated the need for recovery of compounds from the secondary discharge stream of the investigated method to further minimize the carbon and nitrogen loss as a resource.