LAUSR

Abstract This work evaluated two different ages (6 and 12 months) of Opuntia ficus indica cladodes using chemical and biological methods for hydrolysis. The sugars released were analyzed by HPLC, and the hydrolyzates were subjected to fermentation with Candida intermedia, a yeast isolated during the cladode collection process. The results indicated that up to 30 g/L of sugars are released during acid hydrolysis; mucilage is the compound that is fully hydrolyzed. Enzymatic hydrolysis increases the yield of sugars by 73 %, significantly increasing glucose release for 12-month cladodes, indicating that enzymatic hydrolysis favors the release of glucose and that more fiber in the 12-month cladodes increases the presence of cellulose. The hydrolysate fermentation generated up to 7.6 g ethanol/L, and carbohydrate analyses indicated the total glucose consumption followed by fructose, arabinose, galactose, and xylose. The stoichiometric balance showed a real ethanol yield very close to the theoretical one, with no inhibition processes observed due to other sugars' presence. The results obtained indicate that hydrolyzate as a basis for yeast growth is viable; however, specialized microorganisms are necessary to increase ethanol yields.