Efficient starch recovery from cassava bagasse: Role of cellulase and pectinase

Abstract

Cassava is an important industrial crop in Vietnam for the production of cassava starch as the key raw material in biotechnology and related industries. However, the cassava starch industry discharges a large amount of wet bagasse. The bagasse, which contains 50-60% starch and 25-30% cellulose, is currently used with low value and causes severe environmental concerns. In another way, the bagasse can be a source of value-added products if starch is recovered and resulting cellulose is used to develop renewable materials. Recovery of starch and cellulose from the cassava bagasse will have a double impact: improve the total value of cassava production and reduce the risk of environmental pollution. Residue starch granules are entrapped in the cell wall matrix. Therefore, 10 recover starch from the bagasse and cellulose thereof, the cell wall matrix of bagasse should be cleaved but not be degraded. ln this paper, enzymes were used for treating the bagasse, liberating the starch and resulting cellulose materials. The samples of cassava bagasse were treated either with pectinase (Pectinex Ultra SP-l. Novozymes) and cellulase (NS22 l92, Novozymes) alone or with their mixture at various enzyme ratio. The response surface methodology was used to fit the experimental data and investigate the enzyme interaction and the influence of the enzyme loading on the starch recovery yield. The highest starch yield of 87.85 % was achieved by treatment of the bagasse with 13.5 CMCU and 7 PGU per gram of dry bagasse at 45°C and pH 4.8 for 4 hours at the solid loading 5 %.