When chymosin was extracted by ultrasound curd tension and syneresis were significantly lower for Berridge substrate coagulated by the ultrasound-treated chymosin than by the control. Experimental chymosin had a shorter induction period and was more heat-sensitive than the control. Activation energy of chymosin obtained by ultrasound treatment was significantly lower than that of the control. Ultrasound treatment did not significantly change the chromatographic patterns of chymosin. Only two distinct enzymatically active proteins were observed with DEAE-cellulose chromatography. Electrophoretic properties were similar for chymosins obtained by ultrasound and control methods.

The effects of ultrasound treatment on the properties of chymosin and the ultrastructure of abomasum during chymosin extraction were investigated. U1trasound treatment at 36 Wlcm2 for 80 min did not decrease chymosin activity and its proteolytic activity. However, high intensity ultrasound (157 Wlcm2) and the prolonged exposure to high intensity signifzcantly decreased chymosin activity and its proteolytic activity. Ultrasound treatment changed amino acid composition of chymosin. There were signijcant changes in the mole percent of histidine. proline, tyrosine, methionine, valine, and lysine at the lower specijic intensity. Ultrastructure of abomasal tissue was not affected by ultrasound treatment at specifzc intensity 36 Wlcm2 for 80 min. However, some mitochondria cristae were damaged and secretory granules were more compact even though their numbers remained the same.