Fermentation bioethanol production

Metabolite profiling under very high gravity ethanol fermentation Bioethanol production [352]... 

The compactness and complexity of (ligno)cellulose makes it much more difficult to attack by enzymes with respect to starch. Therefore, the cost of bioethanol production is higher [23], To be cost competitive with grain-derived ethanol, the enzymes used for biomass hydrolysis must become more efficient and far less expensive. In addition, the presence of non-glucose sugars in the feedstock complicates the fermentation process, because conversion of pentose sugars into ethanol is less efficient than conversion of the hexose sugars. 

Bioethanol production by yeasts is widely used for biodegradation of potato. However, yeasts cannot ferment starch directly, and a two-step enzymatic reaction to glucose is necessary. Different potato wastes such as industrial residues, low-grade potatoes, and spoiled potatoes can be used for acetone/ethanol production (Nimcevic et al., 1998). They used whole potato media... 

The simultaneous bioconversion of mixed sugar syrups is one of the most ambitious challenges in the field of bioethanol production. Different productivities and ethanol-tolerance of the yeasts used in the fermentation of glucose and xylose (the most abundant biomass sugars) have led... 

The use of recombinant microorganisms for cofermentation is one of the most promising approaches in the field of bioethanol production, though their use for large-scale industrial processes still requires fine-tuning of the reliability of the entire process (2). The technical hurdles of cofermentation increase when real biomass hydrolysates have to be fermented. In fact, whatever the biomass pretreatment, the formation of degradation byproducts that could inhibit the fermentation usually requires the addition of a further detoxification step. Therefore, the production of ethanol from hydrolysates should be considered in its entirety, from the optimal pretreatment to the choice of the proper fermentation process. 

Metabolite profiling under saccharification and fermentation of lab/industrial strains Bioethanol production [351]... 

Bioethanol produced from biomass resources by fermentation is the most promising biofuel and the starting material of various chemicals. Starch is a cheap, clean, nontoxic, renewable Ccirbon source for bioethanol production [1]. In the process currently employed for industrial-scale ethanol production from starchy materials, starch is first hydrolyzed by adding a liquefying enzyme, a-amylase (EC 3.2.1.1), to avoid gelatinization and then... 

High concentrations of ethanol inhibit the fermentation process, ptirticularly when a fermentative medium with high suhstrate concentration is used, as is the case in the majority of the industrial processes. Considering this, Silva et al. [1] studied a process of fermentation combined with a flash vessel, which selectively extracts ethanol firom the medium as soon as it is produced. These authors have shown that this scheme presents many positive features and better performance than conventional industrial processes [2]. Cardona and Sanchez [3] point out that the reaction-separation integration is a particularly attractive alternative for the intensification of bioethanol production. When bioethanol is removed fiom the culture broth, its inhibition effect on the growth rate is diminished or neutralized. However, the performance of the whole process is significantly influenced by separation unit, and that means that thermod)mamic knowledge of the mixture is required. 

The extractive fermentation process for bioethanol production proposed by Silva et al. [1] is shown in Fig. 1. TTie process is composed of four interlinked units feimentor (ethanol... 

The most commonly produced biofuel is bioe taiiol, which is ethanol (C2H5OH) made from fermentation of plant carbohydrates. The fuel value of ethanol is about two-thirds that of gasoline and is therefore comparable to that of coal (Table 5.5). The United States and Brazil dominate bioethanol production, together supplying 85% of the world s total. 

Worldwide, ethanol is mostly produced by fermentation, accoimt-ing for up to 90% of ethanol produced globally. In Brazil, most bioethanol is produced from sugarcane or molasses and in the United States from com. However, other starch materials such as wheat, barley and rye are also suitable as raw material. The starch-containing grains have to be converted into sugar. Thus, in Europe, starch grains, e.g., wheat and sugar beet are the major source of bioethanol production (15). 

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