Abstract:

In this study, the process conditions for extracting polysaccharides from yacon fruits with the assistance of ultrasound were optimized by single factor and orthogonal array design methods. The optimal extraction process conditions were determined as follows: ultrasound power, 80 W; extraction temperature, 50 ℃; and material/liquid ratio, 1:30 (g/mL) for an extraction duration of 15 min. Under these conditions, the extraction yield of polysaccharides from yacon fruits was 53.3%. The decreasing order of importance of the four process conditions affecting polysaccharide extraction was extraction duration, extraction temperature, ultrasound power and material/liquid ratio. The crude polysaccharides obtained had strong hydroxyl free radical scavenging effect, with an IC50 of 1.82 mg/mL, which was more than 20-fold increased after protein removal, revealing an IC50 of 0.085 mg/mL.

Key words: yacon, ultrasound, polysaccharide, extraction process, hydroxyl free radicals