Abstract

A new ultrasound-assisted lactic acid-pepsin hydrolysis method was used to extract yak hide collagen. In the extraction process, a strong mechanical vibration wave and cavitation destroyed the interaction between collagen and its matrix. Lactic acid made collagen fibres loose enough and shortened the extraction time. Lactic acid had also a certain antiseptic and bactericidal effect. Pepsin could remove the non-helical structure of yak hide collagen and reduce the risk of immune rejection of yak hide collagen. The optimum conditions of ultrasound-assisted lactic acid-pepsin hydrolysis method were as follows: At first, degreased yak hide was soaked in lactic acid solution with pH2.0 for 24 hours and control the liquor ratio of 15. Then, acid treated yak hide was soaked in 2.0% (dry hide) pepsin solution with pH2.0 for 24 hours and control the liquor ratio of 15 under pulsating ultrasound treated with 20KHz ultrasonic power 200W for 20 minutes. UPYC had the characteristics of type I collagen. The new ultrasound-assisted lactic acid-pepsin hydrolysis method shortened the extraction time of UPYC, which was economical and clean.