High moisture twin screw extrusion of sage starch .2. Saccharification as influenced by thermomechanical history

Processing of sage starch in a co-rotating twin screw under high-moisture conditions (34-47% moisture, barrel temperatures 81-147 degrees C and screw speed 315-486 rpm) was investigated as a pre-treatment for subsequent saccharification. Product thermomechanical history was assessed for the various processing conditions. Specific mechanical energy (SME) consumption was in the range 57-131 kWh/kg. Saccharification of the extrudates was independent of the processing variables at a higher enzyme concentration of AMG (0.5 AGU/g). However, when 0.05 AGU/g AMG was used, saccharification was related to the extrusion variables. Despite a poor negative correlation between saccharification and SME (r=-0.44), a global trend was observed. Die pressure influenced saccharification (r=-0.45) suggesting that a high melt viscosity (as indicated by high die pressure) resulted in a lower percent of saccharification. Additionally water solubility index (WSI) was influenced by SME to a lesser extent. (C) 1997 Elsevier Science Ltd.