| Prickly ash(Zanthoxylum bungeanum) seed is the main by-product of prickly ash which is riched in protein, it’s amino acid composition are complete and has high levels, which is a high quality and ono-toxic novel plant protein resource. But few reports on the further development of the use on prickly ash seed protein, which only focuses on the extraction of prickly ash seed protein and seed oil. In this paper, prickly ash seed proein as material was applied to prepare angiotensin peptides by response surface methodology which was used to optimize the process conditions. Meanwhile, its isolating and purifying was carried out,and the main process properties were investgated. The main results are as follows:1. Prickly ash seed protein was enzymolysised by trypsin, papain, neutral protease, alcalase and protamex to prepare angiotensin peptides. Papain was found to be the best enzyme for the enzymatic preparation of antihypertensive peptides with angiotensin converting enzyme (ACE) inhibitory activity. The ACE inhibitory activity of enzymatic hydrolysates of Sichuan prickly ash seed protein was investigated as variables of hydrolysis time, enzyme dosage, temperature and pH. The results indicated that the obtained regression model represented the functional relationship well, and the optimal hydrolysis conditions were found as follows:substrate concentration,3 g/100 mL; hydrolysis time,4.9 h; enzyme dosage,10 200 U/g; hydrolysis temperature,37 ℃; and pH,6.9, resulting in an ACE inhibitory rate of 68.00%.2. The hydrolusate was filtrated through ultra-filtration membranes with weight cutoff (MWCO) 5 kDa and had remarkable ACE inhibitory activity, reaching up to 78.75% (p<0.05). The method of Sephadex G-25 gel chromatography was used to purify the solution first. Flow rate, initial volume and sample concentration were analyzed. The filter solution was isolated four peaks when eluted with ultrapure water at a flow rate of 0.6 mL/min, initial volume at 2.0 mL and sample concentration was 30 mg/mL.The second peak had the strongest inhibitory to ACE (85%), IC50 was 0.021 mg/mL. Its molecular weight was below 3 kDa by Tricinne-SDS-PAGE.3. The amino acid composition of angiotensin peptides from prickly ash seed protein was determinated. The processing adaptability and stability of 5 kDa retentate were aslo investigated. The results showed that the amino acid composition of hydrolysates, retentates, permeates and chromatographic fractions was complete, and the content of glutamic acid was the highest. It was 6.96%、6.58%、4.15% and 0.69%, respectively. The solubility of retentate was good more than 80% in a wide range of pH (2.0～10.0). Its oil absorbency was high, the average value was 4.0 mL/g at a temperature of 30～70℃. With pH rising from 2.0 to 10.0, the foaming property of retentate first reduced then increased, While the foam stability was opposite. The emulsifying ability of retentate improved with the increase of pH, while the emulsion stability first decreased then went up. When after a certain heat treatment (63～95℃), its ACE inhibitory activity retained 48%, which had a little change(p>0.05); it keep 47% under different condition of pH. After 72 h of light, ACE inhibitory activity of retentate decreased from 44% to 40%, the difference was not significant(p=0.12). Its ACE inhibitory activity contained 50% after the reaction with glucose, lactose and sucrose, the carbohydrate had a little influence (p>0.05) on it’s ACE inhibitory activity. In addition, when the antihypertensive peptides digested by the pepsin and trypsin, it could maintain a higher ACE inhibitory activity. |
PDF Full Text Request