| The preparation of peptides with high degree of hydrolysis (DH) from peanut protein via enzymatic hydrolysis was investigated. Selecting alcalase and bromelain, the conditions of single protease hydrolysis, compound protease hydrolysis and pretreatment were studied. It was found that although the optimization of single protease hydrolysis process could achieve a higher degree of hydrolysis (27.85%,23.40%), the hydrolysis time was long (386.25, 382.68 min) and the mass concentration of substrate was low(1.09,1.07 g/100 mL).Except the Na2SO3 pretreatment, heat pretreatment and ultrasound pretreatment had no significant effect on DH. The results showed that the optimal enzymatic hydrolysis conditions were obtained as follows：with peanut protein(mass concentration 5 g/100 mL) as raw material, pretreatment with Na2SO3 (mass concentration 0.07 g/100 mL); then the pretreated peanut protein solution was hydrolyzed by alcalase under the conditions of pH 8.0, temperature 50℃, dosage of enzyme 7 429.79 U/g and hydrolysis time 120 min. After the reaction system was adjusted to temperature 45℃ and pH 6.8, 7 642.50 U/g of bromelain was added to hydrolyze for 120 min, and the DH of protein was determined as (33.21±0.70)%. The results of spontaneously hypertensive rats(SHR) experiment indicated that after 4 h,the systolic blood pressure of rats significantly reduced with an oral administration dosage of 1 000-1 500 mg/kg (based on body weight), and the effect could last 8 h. Therefore, the enzymatic hydrolysate (peanut protein peptides) had obviously antihypertensive activity. |
