Valorization of sugarcane bagasse and sugar beet molasses using Kluyveromyces marxianus for producing value-added aroma compounds via solid-state fermentation

Abstract

The growing demand for natural products has favored the development of bioprocesses for obtaining value-added products in the fragrance and flavor sector. Solid-state fermentation (SSF) of agro-industrial residues together with generally recognized as safe (GRAS) strains like Kluyveromyces marxianus appears as a remarkable alternative for producing aroma compounds. In this study, a continuous air supplied system was used for optimizing the production of fruit-like compounds via SSF of a mixture of sugarcane bagasse/sugar beet molasses employing K. marxianus. The main operational parameters were evaluated to identify the best conditions for their biosynthesis. Maximum cumulative volatile production was achieved at 40 °C, 35% molasses (dry basis) and specific air flow rate (SAFR) 0.14 L h−1g−1ITS reaching 161 mgTVOL per gram of initial total solids content (ITS). The main components of the produced volatiles were alcohols (43%) while ester species constituted only 18%. Selectivity to ester species was enhanced working at 30 °C, 25% molasses and SAFR 0.11 L h−1g−1ITS, maximizing the ester content to 47.6 mgEster g−1ITS. In this case, a pleasant fruity odor was perceived thanks to the higher ester content (35%). Stressing conditions for K. marxianus like high temperatures and limiting nitrogen availability seem to be key factors for promoting the production of the volatile compounds.