Possibilities of the utilization of rice husk and subsequent chemical conversion of hemicellulose into xylose, followed by furfural, xylitol, xylonic acid, and ulti­mately the food yeast is explored [55]. Similarly, hydrolysis of cellulose to glucose which, then, can be converted into ethanol, sorbitol, hydroxy methyl furfural, levulinic acid, etc. is outlined. However, ethyl alcohol production would be eco­nomical only if all the by-products are recovered and processed. Mucilagenos material from cocoa waste is another source of alcohol [129]. The waste from tapioca spent pulp after concentration by centrifugation to 20% solids after hydrolysis holds promise for production of alcohol.

9.7.9 Barley

The waste from a novel, vacuum distillation procedure (30-45°C) called Mugi (Barley) contained a large number of viable yeast (7 x 106 cells/ml), with glu — coamylase (19.7 units/ml), acid protease (940 units/ml), and neutral protease (420 units/ml). The waste was mixed with mash composed of glucose as the sole source of carbon. After distillation of fermentation broth, the non-volatile residues were again used in the next ethanol fermentation and the cycle was repeated successfully ten times. The system is developed for the distillery waste which is treated as per the conventional waste water [186].