초록
This research examines the acid hydrolysis of Curcuma longa waste, to obtain the hydrolysate containing lactic acid and ethanol fermentative sugars. A central composite design for describing regression equations of variables was used. The selected optimum condition was 4.91% sulphuric acid, 122.68<SUP>o</SUP>C and 50min using the desirability function under the following conditions: the maximum reducing sugar (RS) yield is within the limited range of the 5-hydroxymethylfurfural (HMF) and furfural concentrations. Under the condition, the obtained solution contained 144g RS/L, 0.79g furfural/L and 2.59g HMF/L and was directly fermented without a detoxification step. The maximum product concentration, average productivity, RS conversion and product yield were 115.36g/L, 2.88g/L/h, 89.43% and 64% for l-lactic acid; 113.92g/L, 2.59g/L/h, 88.31% and 63.29% for d-lactic acid; and 55.03g/L, 1.38g/L/h, 42.66 and 30.57%, respectively, for ethanol using a 7-L jar fermenter.