Behzad Kanani, Alireza Zahedi, Salman Movahedirad, Sina Tamiz
Vacuum fermentation has emerged as a promising process intensification strategy to address long-standing efficiency and sustainability challenges in industrial bioethanol production. As a widely used renewable fuel and functional processing aid, bioethanol plays an important role in the energy and food sectors. However, conventional fermentation processes face significant bottlenecks, including bioethanol and carbon dioxide inhibition, reduced yeast activity, extended fermentation time, and high energy demand for downstream separation. This review presents the first comprehensive technical analysis of vacuum fermentation, a method that enables in-situ bioethanol removal under reduced pressure conditions. This method enhances bioethanol productivity by up to 12 times, and reduces fermentation time by 30 %. By continuously extracting bioethanol, yeast concentration increases 1.5 times, and as a result sugar consumption enhances compared to conventional approach. Unlike pervaperation and gas stripping, VF avoids membrane fouling, high costs, and eliminates additional separatoin steps. Optimal operational conditions are identified as 0.067–0.1 bar pressure, 30–35 °C temperature, and pH between 4.5 and 5.5. Beyond performance improvements, vacuum fermentation contributes to sustainable production by reducing energy usage in distillation, lowering water consumption, and minimizing wastewater and vinasse generation. This review also offers a comparative evaluation of vacuum fermentation against other separation and inhibitor removal methods, providing insights for cleaner, more efficient bioethanol production systems. • Vacuum fermentation increases bioethanol productivity by up to 12 times. • Rapid bioethanol removal under vacuum reduces its inhibitory effects on the yeast. • Optimizing pressure and temperature increases the fermentation rate by up to 30 %. • Vacuum fermentation with multi-stage distillation reduces energy consumption. • Using this method can reduce bioethanol production costs by up to 24 %.