Sustainable valorization of grape pomace via cellulose extraction and cultivation of Tetradesmus obliquus: a biorefinery approach
Grape pomace is a promising agro-industrial residue with significant potential for sustainable biorefinery applications due to its high content of bioactive compounds and nutrients. This study evaluated its use as a substrate for Tetradesmus obliquus cultivation in photobioreactors and its effects on biomass growth and biochemical composition. Three photobioreactors were operated using Bold’s Basal Medium (BBM): one supplemented with grape pomace extract obtained by acid hydrolysis (E1), another with grape pomace extract obtained by microwave-assisted ethanol extraction (E2), and a control containing only BBM. Microalgal cultivation was monitored for 30 days by measuring cell density, growth kinetics, and pH. After cultivation, lipid profile, protein content, mineral accumulation, antioxidant activity, and cellulose crystallinity were analyzed. All treatments exhibited typical growth kinetics, with an exponential growth phase between days 5 and 10 and maximum cell density on day 26. E2 promoted the highest biomass growth, reaching 1.34 × 10 7 cells mL −1 and a specific growth rate of 0.083 day −1 . In contrast, E1 improved biomass quality by increasing protein content, antioxidant activity, and cellulose crystallinity, while reducing the proportion of saturated fatty acids. Grape pomace extracts effectively modulated the growth and metabolism of Tetradesmus obliquus. While E2 favored biomass productivity, E1 enhanced the biochemical characteristics of the biomass, demonstrating the potential of grape pomace as a sustainable substrate for microalgal cultivation and supporting its application in integrated biorefinery processes.