How is ethanol produced from glucose rich fruits and grains

The process flow diagram below shows the basic steps in production of ethanol from cellulosic biomass. Note that there are a variety of options for pretreatment and other steps in the process and that several technologies combine two or all three of the hydrolysis and fermentation steps within the shaded box.

Chart courtesy of the National Renewable Energy Lab. Ethanol Consumers Producers Retailers. How is Ethanol Made? This cellulosic ethanol is considered an advanced biofuel and involves a more complicated and costly production process than fermentation.

However, there are large potential non-food crop sources of cellulosic feedstocks. Trees, grasses, and agricultural residues are potential feedstocks for cellulosic ethanol production. Trees and grasses require less energy, fertilizers, and water to grow than grains do, and they can also be grown on lands that are not suitable for growing food crops.

Scientists have developed fast-growing trees that grow to full size in 10 years. Many grasses can produce two harvests a year for many years without annual replanting. Despite the technical potential for cellulosic ethanol production, economical production has been difficult to achieve and only relatively small amounts of cellulosic fuel ethanol have been produced United States.

In the s, ethanol was a major lighting fuel. During the Civil War, a liquor tax was placed on ethanol to raise money for the war. The tax increased the price of ethanol so much that it could no longer compete with other fuels such as kerosene.

Ethanol production declined sharply because of this tax, and production levels did not begin to recover until the tax was repealed in In , Henry Ford designed his Model T, a very early automobile, to run on a mixture of gasoline and alcohol. Ford called this mixture the fuel of the future.

In , when Prohibition began, ethanol was banned because it was considered an alcoholic beverage. It could only be sold when mixed with petroleum. Ethanol was used as a fuel again after Prohibition ended in Ethanol use increased temporarily during World War II when oil and other resources were scarce.

In the s, interest in ethanol as a transportation fuel was revived as oil embargoes, rising oil prices, and growing dependence on imported oil increased interest in alternative fuels.

Since that time, ethanol use and production has been encouraged by tax benefits and by environmental regulations that require cleaner-burning fuels. Nadir et al. In addition, more time is required to complete fermentation at lower temperature though ethanol yield is the lowest.

For example, only Agitation plays important role in getting higher yield of ethanol during fermentation by increasing the permeability of nutrients from the fermentation broth to inside the cells and in the same way removing ethanol from the cell interior to the fermentation broth.

Agitation also increases the sugar consumption and reduces the inhibition of ethanol on cells. Liu and Shen [ ] reported the maximum ethanol yield Nevertheless, excess agitation rate is not suitable for smooth ethanol production due to the limited metabolic activities of cells. Initial sugar concentration is an important influencing parameter as it has the direct effect on fermentation rate and microbial cells. The actual relationship between initial sugar content and the fermentation rate is rather more complex.

Generally, fermentation rate will be increased with the increase in sugar concentration up to a certain level. But excessively high sugar concentration will exceed the uptake capacity of the microbial cells leading to a steady rate of fermentation. In batch fermentation, increased ethanol productivity and yield can be obtained at higher initial sugar concentration, but it takes longer fermentation time and subsequently increases the recovery cost.

Similarly, the optimal ratio of sugar and microorganism concentration was reported as Inoculum concentration does not have significant influence on final ethanol concentration but significantly affects sugar consumption rate and ethanol productivity [ 44 ].

Increased cell concentration within a certain range also reduces fermentation time considerably due to the rapid growth of cells in the fermentation media that immediately consumes fed sugars producing ethanol. Although current industrial fermentation for fuel ethanol production employs two types of feedstocks such as free fermentable sugars and starch, free sugars containing juice is more economic than starch feedstocks as the former can directly be used in fermentation without any prior treatment.

However, better yield also depends somewhat on the selection of microorganisms and fermentation mode and techniques as well as the influence of several factors. In addition, selection and development of different potential genetic varieties of juice producing crops will also enhance the commercial ethanol production. Several technological advances have already been investigated but most of them are still confined to the laboratory. Therefore, a comprehensive economic and process analysis is required to develop an industrially suitable production strategy that will solve our energy crisis by producing more ethanol in a stable way.

The authors declare that there is no conflict of interests regarding the publication of this paper. This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Academic Editor: L. Received 04 Oct Accepted 31 Dec Published 12 Mar Abstract Bioethanol production from renewable sources to be used in transportation is now an increasing demand worldwide due to continuous depletion of fossil fuels, economic and political crises, and growing concern on environmental safety.

Introduction Energy crisis is a growing global concern nowadays because of the dependence on petroleum-based fossil fuel which is exhausted very fast to meet the continuously increasing demands.

Potential Juices Used as Feedstocks Bioethanol can be produced directly from the free sugar containing juices of some crops, converting sucrose or monosaccharides, especially, glucose, into ethanol via fermentation with microorganisms [ 23 , 24 ]. Name of the crops Major investigation Major achievements Reference Sugarcane Saccharum officinarum Juices were studied i without adding supplement, ii with addition of 0.

Table 1. Different sugar crops investigated for ethanol production using sugar juices as feedstocks. Table 2. Chemical composition of feedstocks derived from different crops. Table 3. Growth condition of microorganisms involved in ethanol fermentation. Table 4. Fermentation process employed in ethanol production from different feedstocks. References S. Prasad, A. Singh, and H. Naik, V. Goud, P. Rout, and A. Ogbonna, H. Mashima, and H. Nagashima, M. Azuma, S. Noguchi, K. Inuzuka, and H.

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Among the fuels, bioethanol stands out for having great potential to boost regional economy. Ethanol can be produced from any polysaccharide that contains sugars or starches, even when structured in larger molecules. Sugar-based raw materials, such as sugar cane, are commonly used in Brazil and in other countries and represent the biomass most widely used for the production of ethanol Teetor et al. Starchy materials such as corn, cassava, sweet potato, potato, wheat and rice can also be raw materials used to produce ethanol in high yield Shanavas et al.

In this scenario, Brazil contributes with 13,,t 2. The largest consumption of rice is as food in the form of grains that can be cooked or fried, sake and extruded snack foods Juliano, Rice is an excellent source of energy. Due to its high concentration of starch, rice is suitable for the production of bioethanol Kennedy, ; Chu-Ky et al.

Typically, ethanol production is an exothermic reaction in which New varieties of rice have been studied as energy sources. Some of these varieties have characteristics different from those required for human consumption, such as that known as giant rice, which is hardy but adaptable to the soil and climatic conditions in southern Brazil.

Another source is broken rice or grits, which comes from industrial waste processing of grains Carvalho et al. The use of this waste, which is rich in starch, is mainly as animal feed and may contain contaminants such as rice husks, barnyard-grass seeds Equinocloa spp.

Irineo et al. This study aims to analyze an alternative for the production of bioethanol fuel in the state of Rio Grande do Sul, through the use of broken rice and waste from the rice production system not intended for human consumption.

The rice used in the experiments consisted of 50kg of polished white broken rice grains, types 3 and 4. The samples were ground in a hammer mill to form a flour. Particle size was determined through the use of a sieve shaker with intermittent beats APBIH7 - PHD equipment using sieves of 28, 32, 48, 60, and mesh.

Starch content was determined by mass difference after the removal of proteins. To remove the proteins 15g of the sample were mixed with 6 volumes of NaOH 0.

The remaining solid was collected and mixed again with the same basic solution. The procedure was repeated until the biuret test 1ml of the supernatant over 4ml of biuret solution showed no positive signs for the presence of proteins Zaia et al.

The reduction of proteins in the supernatant was observed after about six washes, when the color the solution changed from the initial purple to blue. The methodology followed the basic instructions provided by the product manufacturer, which contained information on the temperature optimization and enzyme concentration to be applied in the hydrolysis Novozymes, Initially, the sample was pretreated by boiling for 0.

Afterwards, the pH was adjusted to 4. The second stage was also conducted for 2h in a water bath under stirring. Samples were taken at regular time intervals for sugar analysis using high performance liquid chromatography HPLC.

After saccharification of the samples, the hydrolyzate was fermented with Saccharomyces cerevisiae Angel Thermal Resistance Alcohol Yeast with the purpose of producing bioethanol, according to the methodology of Vancov et al. Fermentation was performed in ml autoclaved bottles, to which 50ml of the filtered hydrolyzate, 0.

After cooling, 0. Samples were taken at regular time intervals for sugars and bioethanol determination by HPLC. The samples were previously centrifuged at 14,rpm in a centrifuge Mini Spin - Eppendorf and filtered through a 0. Statistical analysis of the data was performed using the Kruskal-Wallis test and Assistat Software version 7.