**8. The treatment of wastes of food industries**

Reports have described the use of SCFs for the treatment of lignocellulosic materials, which are the major group of wastes of food industries e.g. straw and bran of corn and cereal, leaf and pomace of sugar cane, fruitwaste, etc. SCF treatment allows further utilization of lignocellulosic materials as a resource for chemicals, pulp, and energy (Puri, 1983). Pretreatment methods have been sought to remove lignin and to permit further utilization of carbohydrates contained in lignocellulosic materials. Several SCFs (e.g. SC-methanol, SCacetone, and SC-ammonia) an alternative to chemical pretreatments, which use strong acids or bases. Ammonia-treated lignocellulosic materials were neutralized and buffered to a pH value of 4.8 before being incubated at 50°C with a fractionated and partially purified commercial crude cellulose preparation from *Trichoderma reesei*. Aliquots taken at various times were filtered before being analyzed for sugars by HPLC. Two long-term experiments were made with diets consisting of preparations of spent hops and a sample of apple pomace, incubated in the Rumen Simulation Technique (RuSiTech). A significant increase in the total volatile fatty acids and methane production was observed when the preparations of spent hops were incubated in separate bags rather than in mixtures with other components (Cansell et al., 1997). Lignin, cellulose, and their mixture were gasified with a nickel catalyst in SC-water at 673 K and 25 MPa. The gasification efficiency was low, but increased with the amount of the catalyst when softwood lignin was included in the feedstock. One possible mechanism is the catalyst being deactivated by tarry products from the reaction between cellulose and softwood lignin. Sawdust and rice straw were gasified under the same condition (Yoshida et al., 2004).
