Like sugar cane, sugar beet can also be used to obtain bioethanol by fermenting and distilling its juice. The beet is first cut into thin slices, then placed in contact with a medium (water or juice extracted from a previous process) and brought up to a temperature of about 70-80°C. In the case of sugar beet, temperature is a fundamental extraction parameter because it must be high enough to rupture the proteins in the cell walls containing the sugars, which has the effect of allowing the sugars to spread through the medium. Once this process has been completed, the sugar beet pulp is dried and sold as animal feed or to the pharmaceutical industry for use in the production of citric acid and its esters. The beet juice proceeds instead through the stages that convert it into bioethanol. At plants where sugar and bioethanol are both produced together, the juice can either be used directly or it can be concentrated in evaporators and stored for several months. Both the fresh and the concentrated sugar juice can be used in production processes involving cold crystallization and fermentation. The fermentation process relies on the use of yeasts (preferably Saccharomyces cerevisiae) or bacteria such as Zymomonas mobilis (Linde et al., 1998), which is only used in the case of a discontinuous fermentation. The great interest focusing on the bacteria is due to their capacity to convert the glucose into ethanol more efficiently than yeasts succeed in doing. Figure 4 shows the flow chart for the production of bioethanol and byproducts from sugar beet.

Fig. 3. Flow chart for bioethanol, energy and sugar production from sugar cane