Recovery of starch from cassava bagasse for cyclodextrin production by sequential treatment with α-amylase and cyclodextrin glycosyltransferase

Abstract

Abstract This work aimed at the enzymatic recovery of starch from cassava bagasse using α-amylase and the production of cyclodextrins (CDs) by cyclodextrin glycosyltransferase (CGTase). Cassava bagasse containing 50% (w/w) starch (dry basis) was hydrolyzed by α-amylase until a maximum starch recovery as a maltooligosaccharide solution. Afterwards, this solution was used for the production of CDs using CGTase as biocatalyst. Optimal conditions for starch extraction using α-amylase were 60 °C and 0.15 mL enzyme/kg dry bagasse, with 93% starch recovery. Several operational parameters were evaluated to optimize the CD yields, such as starch dextrose equivalent (DE), temperature and CGTase loading. The starch DE did not significantly influence the production of CDs, resulting in a similar yield for all experiments (43%). The highest productivity of CDs (93.6 mg of CDs per enzyme Unit) was obtained using an enzyme loading of 2.5 U/g starch for 1 h at 60 °C and pH 6.0. After 6 h of reaction at 60 °C and pH 6.0, the CD yield reached a value of 50%. These findings did indicate that cassava bagasse is a promising feedstock for the production of CDs using this bi-enzymatic system.