Ultrasonic extraction technology of saponins and its antioxidant activity in quinoa from Qinghai

Extraction conditions of quinoa saponins from Qinghai were investigated by single factor and orthogonal test on ultrasonic assisted solvents, the content of saponins and antioxidant capacity of different quinoas in Qinghai were analyzed.The results showed that: the volume fraction of ethanol was 90%, solid-liquid ratio was 1∶ 15 ( g/m L) , extraction time was 20 min, ultrasonic power was 400 W and extraction temperature was 45 ℃.Under these conditions, the saponins content of quinoa was115.74 mg/100 g. The average content of saponins in 119 quinoa was ( 93.66 ± 18.34) mg/100 g, saponins content and antioxidant activities among different quinoas were great different. Among different grain colors, the content of saponins in red quinoas was the highest and the antioxidant activities was the strongest, the saponins content of white quinoas was the lowest and the antioxidant activities was the worst.119 quinoas were divided into three classes by Ward connection ( square European distance) method based on DPPH· scavenging ability, iron ion reduction ability ( FRAP) and ABTS+·scavenging ability. ClassⅠ ( inciuding 69 quinoas) showed relatively higher saponins content and antioxidant activities, while class Ⅱ ( inciuding 33quinoas) were midium, class Ⅲ ( inciuding 17 quinoas) showed relatively low saponins content and antioxidant activities.Saponins content and antioxidant activities among the three classes were significant different ( p < 0.05) .