Optimization of cassava starch saccharification by ultrasound assisted composite enzymatic hydrolysis

The cassava starch from cassavastarch were saccharified with complex enzymatic methodafter the ultrasonic treatment. Based on the screening of single-factor(ultrasonic time,ultrasonic power,saccharifying time,saccharifying temperature,glucoamylase amount,pH and solid-liquid ratio)experiment design,four experimental factors were selected for the Box-Behnken experimental design using response surface methodology,which gave the optimal extraction conditions:Ultrasonic time of 15 min,ultrasonic power of 900 W,saccharifying time of 100 min,saccharifying temperature of 65 ℃,glucoamylase amount of 5 g/L,pH4.7 and solid-liquid ratio of 9:20 (g/mL).Under these conditions,the saccharification rate(DE value)of cassava starch was 98.98%,which was matched closely to the predicted value. In addition,FT-IR and GC-MS analysis showed that treated samples showed characteristic peaks for cassava starch. SEM analyses indicated that the surface structure of cassava starch before ultrasonic treatment was different from that of cassava starch after ultrasonic treatment. This study provides strong evidence that complex enzymatic saccharification after ultrasound-assisted was an excellent saccharification method for cassava starch from cassavastarch.