Utilization of residue from cassava starch processing for production of fermentable sugar by enzymatic hydrolysis

ABSTRACT

Abstract The aim of this study was to characterize and perform enzymatic hydrolysis of cassava peeling residue (peel and inner peel), mainly composed of peels and small pieces. Residue was sanitized, dried at 55 °C for 24 hours and ground. The obtained flour showed pH of 4.85; 72.53 g 100 g-1 moisture; 5.18 mL 1M NaOH 100 g-1 acidity; 60.68 g 100 g-1 starch; 1.08 g 100 g-1 reducing sugar; 1.63 g 100g-1 ash; 0.86 g 100 g-1 lipid and 3.97 g 100 g-1 protein. Enzymatic hydrolysis was carried out by means of rotational central composite design, analyzing the effects of concentrations of α-amylase enzyme (10 to 50 U g starch-1), and the amyloglucosidase enzyme (80 to 400 U g starch-1) on variable responses: percent conversion of starch into reducing sugars (RSC) and soluble solid content (SS). Highest values of RSC (110%) and SS (12 °Brix) were observed when using the maximum concentration of amyloglucosidase and throughout the concentration range of α-amylase. Enzymatic hydrolysis of cassava peel is feasible and allows the use of hydrolysate in fermentation processes for the production of various products, such as alcoholic drinks, vinegar, among others.