Abstract:With the aim to improve the ACE-inhibitory activity of hydrolysates from silkworm pupae protein, a pretreatment method of the coupled ultrasound-ionic liquids was used. Taking ACE-inhibitory activity as index, the technology conditions of silkworm pupae protein pretreatment by the coupled ultrasound-ionic liquids were determined with single factor experiments and response surface methodology. In addition, the molecular weight changes of silkworm pupae protein and its hydrolysate after pretreatment were studied by Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE). The results indicated that the effect sequence of three main factors for ACE-inhibitory activity from big to small was as follows: liquid-solid ratio, ultrasonic power, pretreatment time. The optimal pretreatment conditions were as follows: liquid-solid ratio 27.2 mL/g, pretreatment time 31.9 min, ultrasonic power 406.8 W. Under the optimal pretreatment conditions, the average ACE-inhibitory rate of silkworm pupae protein hydrolysate was 75.7% (IC50=0.071 mg/mL). Compared with the un-pretreatment and ultrasound pretreatment, the pretreatment of the coupled ultrasound-ionic liquids has obvious advantages in increasing ACE-inhibitory activity of silkworm pupae protein hydrolysate. After the coupled ultrasound-ionic liquids pretreatment, the molecular weight of silkworm pupae protein has no significant change, while the molecular weight of its hydrolysate(<1.43 ku) becomes smaller.
