Ultrasonic-assisted Enzymatic Method Preparing Oat Ace Inhibitory Peptides

Oat as a traditional healthy food, with its rich variety of nutrients such as protein, soluble dietary fiber, vitamins and minerals, and their healthy effect, has already demonstrated a good market prospect. A balanced amino acid composition of Oat is a good source of bioactive peptides from plants. Developing Oat bioactive peptides has great significance for the world.Hypertension is a kind of blood pressure is increased as the main symptom, and can cause heart, brain, kidney, retina and other target organ damage and metabolic changes in the clinical syndrome. According to statistics, Hypertension induces cardiovascular and cerebrovascular diseases, the death toll 12 million worldwide each year. Hypertension has become a major global public health problem. Studies have shown that angiotensin-converting enzyme (ACE) activity in reducing blood pressure have a positive effect. Therefore, research and development of effective ACE inhibitors cause great concern. Food source ACE inhibitory peptides with high security and toxic side effects, easy to absorb and so on, has incomparable superiority of synthetic chemicals as anti-hypertensive functional food research is a hot spot.Ultrasonic as a form of physical energy is widely used in medical, industrial, chemical and chemical process, environmental protection, food industry, bioengineering and so on. At present, the application of ultrasonic is more and more concerned, and it relates to the field also will be expanded.In this study, ultrasonic-assisted enzymatic preparation of Oat ACE inhibitory peptides to explore the various proteases hydrolyzed Oat protein, the best condition was obtained as the indexes of the inhibitory capabilities to angiotensin-converting enzyme and the degree of hydrolysis; Oat hydrolysates were isolated and purified, and then based on different molecular weight obtained ACE inhibitory. This study of Oat peptides had a broad research value and application prospect.The results are as follows:1. Studied ultrasonic-assisted enzymatic preparation of Oat processing technology of ACE inhibitory peptide, identified the ultrasound-assisted enzymatic method in extracting traditional advantages of ACE inhibitory peptide; After the single factor experiments to determine reaction conditions, container: plastic cups; enzyme: Alcalase (Novo); pretreatment pH value: 11; ultrasonic processing time: 30min; Ultrasonic Frequency: 50kHz; ultrasonic Power: 176W; ultrasonic water bath temperature: 55℃; water feed ratio: 10: 1; enzymolysis time: 2h; the amount of enzyme: 5%. Then experiments using the center according to Box-Benhnken combination of experimental design principles chose four factors of ACE inhibition rate have a significant effect of: the ultrasonic processing time (X1), ultrasonic power (X2), ultrasonic water bath temperature (X3) and the enzymolysis of time (X4), I did four factors and three levels of response surface analysis experiments as the indexes of the inhibitory capabilities to angiotensin-converting enzyme. Finally, ultrasonic processing time 28.40min; ultrasonic power 190.08W; ultrasonic water bath temperature of 55.05℃; digestion time of 2.25h.2. Experiments used macroporous adsorption resin purified Oat hydrolyzates, demonstrated desugar and desalination effects, and at the same peptides concentration, the purified product of ACE inhibition was higher than that unpurified products; I analyzed the amino acid composition of the products before and after purification, purified Oat ACE inhibitory peptide hydrophobic amino acids, aromatic amino acids and branched-chain amino acid contents were higher than the unpurified. The amino acids analysis proved that purified the ACE inhibitory peptide purified inhibitory activity is higher than unpurified; Application of HPLC measured the molecular weight distribution of the purified ACE inhibitory peptides, the molecular weight distribution of the purified product were 240.10 ~ 1292.11Da, all less than 1500Da, is a good source of follow-up separation of peptides.3. After purification I used Sephadex to separate Oat ACE inhibitory peptides. SephadexG-15 Separated of Oats ACE inhibitory peptides and obtained the optimal conditions, sample concentration:100mg/ml; the sample volume:3ml; flow rate:0.6ml/min; eluting agent: distilled water; Application of the condition obtained the five separate components, through ACE inhibition activities of five components ,and D peak had the highest activities, IC50 was 0.103mg/ml, and its molecular weight is 545, according to average molecular weight I predicted 3 or 4 amino acid in D peak; Through the stability tests, D peak has good pH and temperature stability; In addition, the application of pepsin&trypsin treatment in vitro digestion experiments, ACE inhibitory peptide (D peak) after treatment of digestion, maintained high ACE inhibitory activities. After vitro digestion experiments, Oat inhibitory peptides were possible to lower blood pressure from the gastrointestinal tract to the blood circulation.