Effects of Growth Period and Germination Treatment on Saponin Content of Different Bean Varieties

In order to improve the processing and utilization value of the Northeast snap beans products by clarifying the saponin content, sites and influencing factors, this study extracted saponins from the seeds and pods of seven kinds of Northeast snap beans, including Golden Crown, Green Crown, and Sheng Crown within 10~40 d after blooming using ultrasonic-assisted methods. 0.4%~1.2% sodium chloride solution was used to conduct germination treatment under salt stress on the saponin content of Golden Crown and Mantangcai seed. Finally, ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) was used to identify the saponin species in the seeds of Golden Crown. The results showed that saponin existed mainly in the seeds, and the saponin content increased firstly but then decreased with the increase of growth time. The peak period of saponin content varied with the bean varieties. Compared with the other six varieties of snap beans, the saponin content in the full hall was the highest, with the highest saponin content of Mantangcai whole pods of 23.62±0.14 mg/g at 35 d. The change of saponin content was closely related to the sprouting time of bean seeds and bean varieties. Salt stress treatment could significantly increase the saponin content of Mantangcai seeds from (7.08±0.15) mg/g to (10.15±0.55) mg/g. The UHPLC-Q-TOF-MS analysis showed that there were seven saponins in the crude saponins of the Golden Crown bean, including saikosaponin F, adzuki saponin II and astragaloside IV. This study provides data support for the in-depth development of soybean saponins in Northeast China.