Statistical optimization of hydrolysis process for banana peels using cellulolytic and pectinolytic enzymes

Dried and ground banana peels (BP) were pretreated and hydrolyzed using a combination of cellulolytic and pectinolytic enzymes. Central composite design (CCD) was used to optimize cellulase, p-glucosidase and pectinase concentrations and hydrolysis time for production of glucose and reducing sugars. Design expert software was used to analyze and evaluate the data. The interactions between filter paper cellulase and R-glucosidase concentrations were statistically significant at a 95% confidence level in production of glucose and reducing sugars from BP. The validation experiment was carried out with cellulase, p-glucosidase and pectinase at 8 FPU/g cellulose, 15 IU/g cellulose and 66 IU/g pectin, respectively, for 15 h in a laboratory fermenter. The glucose and reducing sugars concentrations of 28.2 and 48 g/l, respectively, obtained through the validation experiment were higher than the theoretical values for glucose and reducing sugars predicted by the software. Glucose, galactose, arabinose, xylose and galacturonic acid concentrations increased with time, but a significant increase in fructose concentration was not observed. Process optimization also led to about 40% savings in hydrolysis time, indicating scale-up potential for the process. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.