Effect of Ultrasound and Cellulase Pre-Treatment on Extractability and Properties of Taro Starch

Abstract

Ultrasound and cellulase pre-treatment was applied for the extraction of starch from taro tubers andtheir effect on yield and properties of the extracted starch was studied. Ultrasonication time was variedat three levels of 0, 10 and 20 min whereas cellulase concentration was varied at two levels of 0 and200 U/100 g tuber. It was observed that higher yield was obtained with ultrasonication as well ascellulase treatment. When both the treatments were combined, yield achieved was much higher comparedto conventional extraction. Highest yield of 19.36% was obtained when ultrasonication was carried outfor 20 min and was then treated with cellulase at concentration of 200 U/100 g tubers. The functionalproperties was comparable to conventionally extracted starch when cellulase treatment alone wascarried out. The swelling and solubility increased with ultrasonication and was time dependent. Clarityof the starch pastes improved with cellulase treatment and was negatively affected by ultrasonication.Maximum clarity was observed for starch extracted by cellulase treatment only. Freeze-thaw stability ofthe starch pastes improved for ultrasonically extracted starch and was not affected by cellulase treatment.Pasting properties were not much affected by ultrasonication for 10 min and cellulase treatment, butwhen ultrasonication time was increased to 20 min, the peak and final viscosities were found to besignificantly increased. Higher yield of starch with better properties like improved freeze-thaw stability,high paste viscosity and swelling and better clarity can be obtained from taro tubers by combined pre-treatment with ultrasound and cellulase, which will help in the commercial exploitation of this underutilizedtuber.