During cane milling, the soluble fraction is separated from the rest of the plant achieving up to 97% efficiencies for industrial milling and 50% efficiencies for traditional milling (Gonzalez and Gonzalez, 2004). Cane juice is a viscous, greenish liquid. For South American cane varieties, the juice contains 15 to 16% soluble solids, from which 85% is sucrose yielding an approximate content of this sugar in the fresh juice of 12 to 13% (Lindeman and Rocchiccioli, 1979). The average composition of raw cane juice (before its clarification) is presented in Table 3.5. As in the case of the whole sugarcane, an example of the specifica­tion corresponding to the average composition of cane juice is shown in this table using data from India, Venezuela, Colombia, and South Africa (Bhattacharya et al., 2001; Gonzalez and Gonzalez, 2004; Sanchez and Cardona, 2008a; Seebaluck et al., 2008). This average composition was used during most simulations con­ducted for process synthesis purposes.

The clear beet juice obtained in sugar production plants can be used for etha­nol production as well. In general, the beet juice is used during the harvest season when there is a high availability of beets. Out of season, the distilleries produce ethanol mostly from beet molasses or beet syrup (Decloux et al., 2002). The com­position of beet juice does not differ substantially from the composition of cane juice, as reported by Ogbonna et al. (2001).