ultrasonic treatment of SPG. the ultrasonic treatment proces of SPG sample was performed in an ultrasonic cell disintegrator (JY92-II, Xinzhi bio technoogy and science Inc. Ningbo, Zhejiang Province, China). A 20 mL. amount of the SPG solution (5.0% w/v) was placed into a reaction vessel ( a 50 mL glass breaker) , then the breaker was held in the ultrasonic intensity. Ice bathing was used to ensure the temperatre of solution was below 60 C in the whole extraction processing. the ultrasonic intensity was predicted according to the following formular.