Use of tropical maize for bioethanol production

Abstract

Tropical maize is an alternative energy crop being considered as a feedstock for bioethanol production in the North Central and Midwest United States. Tropical maize is advantageous because it produces large amounts of soluble sugars in its stalks, creates a large amount of biomass, and requires lower inputs (e.g. nitrogen) than grain corn. Soluble sugars, including sucrose, glucose and fructose were extracted by pressing the stalks at dough stage (R4). The initial extracted syrup fermented faster than the control culture grown on a yeast extract/phosphate/sucrose medium. The syrup was subsequently concentrated 1.25-2.25 times, supplemented with urea, and fermented using Saccharomyces cerevisiae for up to 96 h. The final ethanol concentrations obtained were 8.1 % (v/v) to 15.6 % (v/v), equivalent to 90.3-92.2 % of the theoretical yields. However, fermentation productivity decreased with sugar concentration, suggesting that the yeast might be osmotically stressed at the increased sugar concentrations. These results provide in-depth information for utilizing tropical maize syrup for bioethanol production that will help in tropical maize breeding and development for use as another feedstock for the biofuel industry.

Phenology and Biomass Production of Adapted and Non‐Adapted Tropical Corn Populations in Central Iowa

“…The features of tropical germplasm produced in temperate environments are well known to be unacceptable from a grain yield perspective. However, taller and more vigorous plants with thick stems and longer leaves, as found in tropical corn, could be attractive from a biomass yield standpoint (Chen et al, 2013). Several studies positively relate morphometric measurements such as height and stalk diameter to vegetative growth and forage biomass (Freeman et al, 2007;Pordesimo et al, 2004).…”

“…Therefore, tropical corn accumulates more sugar during grain filling because kernel set is poor and barrenness often occurs. Furthermore, corn germplasm with delayed flowering, as found in tropical corn, would compensate for the reduction of grain with more vegetative biomass (King et al, 1972;Pulam, 2011;Chen et al, 2013). The source greatly exceeds the sink, especially when grown at longer days.…”

“…Reported results show that delayed flowering, such as found in non-adapted tropical corn, was antagonistic to grain production (King et al, 1972;Pulam, 2011;White et al, 2011;Chen et al, 2013). However, even if corn has been historically cultivated mainly for grain, and all fertilization and water recommendations have been calculated for this purpose, biomass accumulation in tropical corn may be useful for bioenergy, meaning studying corn's overall potential beyond grain, remains relevant (White et al, 2011;Chen et al, 2013;).…”

“…However, even if corn has been historically cultivated mainly for grain, and all fertilization and water recommendations have been calculated for this purpose, biomass accumulation in tropical corn may be useful for bioenergy, meaning studying corn's overall potential beyond grain, remains relevant (White et al, 2011;Chen et al, 2013;). This potential can be better understood through further refined study of phenology and vegetative development of tropical populations.…”

Optimizing Dilute-acid Hydrolysis (DACH) of Distillers Grains and Ethanol Fermentation

“…The various processes involved during the conversion of lignocellulose biomass to bioethanol include pretreatment, saccharification hydrolysis, fermentation and separation [1]. Hydrolysis refers to the processes that convert the polysaccharides into monosaccharide, including of acid or enzymatic hydrolysis processes [2].…”