The Influence of Technological Conditions of Co-Fermentation of Lignocellulosic and Starch Raw Materials on the Amount of Volatile By-Products Formed and the Quality of Obtained Bioethanol

This study investigated the effect of co-fermentation of starch (1G) and lignocellulosic (2G) feedstocks on ethanol production and the profile of volatile by-products. Experiments were conducted using an integrated SHF/SSF method with separate pretreatment of each raw material. After 72 h, the ethanol concentration in the starch–lignocellulosic mash reached 49.39 g/L, which is 77% higher compared to the ethanol concentration from the lignocellulosic biomass alone (27.93 g/L). The ethanol yields were 31.32 and 17.72 L/100 kg of raw material, respectively. Co-fermentation significantly changed the profile of volatile compounds. In the starch–lignocellulosic mash, the content of aldehydes was 51.20 mg/L (43% lower vs. lignocellulose alone), higher alcohols was 2018.17 mg/L (64% lower), esters was 8.70 mg/L (73% lower), and methanol was 1.33 mg/L (98% lower). These results demonstrate that integrating 1G and 2G feedstocks reduces the formation of by-products during the fermentation process, while maintaining ethanol concentrations at an industrial profitability threshold (above 40 g/L). The findings provide important insights for optimizing integrated bioethanol production from whole corn plants, which is essential for improving the economic feasibility.