Energy source, alcohol

The elemental and vitamin compositions of some representative yeasts are Hsted in Table 1. The principal carbon and energy sources for yeasts are carbohydrates (usually sugars), alcohols, and organic acids, as weU as a few other specific hydrocarbons. Nitrogen is usually suppHed as ammonia, urea, amino acids or oligopeptides. The main essential mineral elements are phosphoms (suppHed as phosphoric acid), and potassium, with smaller amounts of magnesium and trace amounts of copper, zinc, and iron. These requirements are characteristic of all yeasts. The vitamin requirements, however, differ among species. Eor laboratory and many industrial cultures, a commercial yeast extract contains all the required nutrients (see also Mineral nutrients). 

Solubility/miscibility One gram soluble in 5 ml water slightly soluble in alcohol Biological considerations White powder. Energy source Chemical compatibility/Stability considerations None... 

Alcohol is a clean energy source that can be produced by the fermentation of biomass. However, it needs to be highly concentrated. In general, aqueous alcohol solutions are concentrated by distillation, but an azeotrope (96.5 wt% ethanol) prevents further separated by distillation. Pervaporation, a membrane separation technique, can be used for separation of these azeotropes pervaporation is a promising membrane technique for the separation of organic liquid mixtures such as azeotropic mixtures [34] or close-boiling point mixtures. 

Y Naoshima, J Maeda, Y Munakata, T Nishiyama, M Kamezawa, H Tachibana. Bioreduction with immobilized baker s yeast in hexane using alcohols as an energy source. J Chem Soc Chem Commun 964-965, 1990. 

Goldemberg, J., Monaco, L., and Macedo, I., The Brazilian fuel-alcohol program. In Renewable Energy Sources for Fuels and Electricity, Johansson, T., Kelly, H., Reddy, A., and Williams, R., Eds., Island Press Washington, DC, 1993. 

THE MAIN POWERHOUSE is the key energy source of Biochemistryland and, in fact, is key-shaped. Its Main Hallway (fig. 1.2) leads to a ferris wheel (Krebs cycle) run by a powerful Generator (oxidative phosphorylation). There is an Energy Hall of Fame (HOF). The Main Powerhouse is situated near a Saloon (alcohol metabolism). 

Production of Oleochemicals Fatty acid esters, which have traditionally been used as flavors, plasticizers, food preservatives, emulsifiers, and lubricants, are receiving renewed interest as an alternative energy source as biodiesel. They can be produced by the esterification of fatty acids and alcohols or by the alcoholysis of vegetable oils/triacylglycerols. 

Source of energy. Alcohol may be useful as an energy source (rather than a food) in debilitated patients. It is rapidly absorbed from the alimentary tract without requiring digestion and it supplies 7 calories per gram as compared with 9 from fat and 4 from carbohydrate and protein. Heavy doses cause hyperlipidaemia in some people. 

See alcohol, denatured alcohol, industrial biomass. Note Ethanol from fermentation of biomass and hydrolysis of cellulose is a significant alternate energy source, especially as an automotive fuel. Its use in gasoline will continue to increase. 

Goldemberg J, Monaco LC, Macedo IC (1993) The Brazilian fuel-alcohol program. In Johansson TB, Kelly H, Reddy AKN, Williams RH (eds) Renewable energy sources for fuels and electricity. Island Press, Washington, DC, p 841... 

---