Journal of Energy Bioscience 2024, Vol.15, No.3, 208-220 http://bioscipublisher.com/index.php/jeb 211 Figure 1 Corn vs. Cassava: Comparative Analysis in Ethanol Production Process (Adapted from Pradyawong et al., 2018) 3.3 Pretreatment methods Pretreatment is a critical step in ethanol production as it helps to break down the complex structure of the corn kernel, making the starches more accessible for enzymatic hydrolysis. Common pretreatment methods include physical, chemical, and thermal treatments. For instance, dilute acid pretreatment has been shown to be effective in breaking down lignocellulosic biomass, such as cassava stems, making the starches more accessible for subsequent enzymatic hydrolysis (Han et al., 2011; Ibeto et al., 2014; Rawaengsungnoen et al., 2018). 3.4 Enzymatic hydrolysis and fermentation Enzymatic hydrolysis involves the use of enzymes like cellulase and β-glucosidase to convert the pretreated starches into fermentable sugars. The efficiency of this process can be influenced by factors such as enzyme loading and reaction conditions. For example, studies have shown that using 20 FPU/g cellulose of cellulase and 30 CbU/g of β-glucosidase can lead to a saccharification yield of 70% (Han et al., 2011). The resulting sugars are then fermented using yeast, typically Saccharomyces cerevisiae, to produce ethanol. The fermentation process can be optimized by controlling parameters such as temperature, pH, and yeast concentration (Han et al., 2011; Martinez et al., 2018; Aziz et al., 2020). 3.5 Distillation and dehydration processes The final steps in ethanol production are distillation and dehydration. Distillation is used to separate ethanol from the fermentation broth, typically resulting in an ethanol concentration of around 10-12 vol%. This ethanol is then further purified using molecular sieves to remove any remaining water, achieving fuel-grade ethanol concentrations of 99.5% or higher. Energy-efficient distillation techniques, such as Very High Gravity (VHG) fermentation, can significantly reduce steam consumption and overall energy costs (Kang et al., 2014). 4 Technological Innovations in Ethanol Production 4.1 Advances in biocatalysts and fermentation technology Recent advancements in biocatalysts and fermentation technology have significantly enhanced the efficiency and yield of ethanol production. The discovery and application of new enzymes have played a crucial role in this progress. For instance, the introduction of proteases and cellulases has improved the starch-to-ethanol conversion process, leading to higher ethanol yields and better downstream processing (Harris et al., 2014). Additionally, the use of solid-state fermentation technology to produce a biocatalyst containing a complex mix of enzymes has shown to significantly improve ethanol production performance, increasing the final ethanol concentration by 6.8% and accelerating the kinetics by 14 hours (Guillaume et al., 2019).
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