Combined effect of ultrasound and enzymatic pretreatment on yield and functional properties of taro (Colocasia esculenta) starch

摘要

A combined effect of ultrasound and enzymatic pretreatment on yield and functional properties of taro starch was investigated. A 3x2x2 factorial design was employed with three factors, i.e., sonication time (0, 10, and 20min), concentration of cellulase (0 and 100U/100g fresh tuber) and xylanase (0 and 100U/100g fresh tuber). Starch yield varied from 14.60 to 20.81%. The highest yield of 20.81% was obtained, when ultrasonication time was 20min and concentration for both cellulase and xylanase was 100U/100g taro tubers, which was an increase of 42.53% from conventional method. An increase in swelling, solubility and pasting properties of the isolated starches pretreated only with ultrasound was observed, but no such difference was observed with enzymes alone, or when ultrasound was applied in combination with enzymes. A slight decrease in clarity of the starch pastes was also observed after ultrasonication. Freeze-thaw stability of the starches was found to be better when ultrasound was used as pretreatment for extraction. Higher yield of starch with better functional properties can be achieved from taro tubers by using combination of ultrasound and enzymes.