The Study Of Angiotensin-converting Enzyme Inhibitory Peptide Produced From Rice Residue Protein

In this paper, rice residue protein preparation was hydrolyzed by alkaline protease to make angiotensin-converting enzyme inhibitory peptides which can reduce blood pressure.Rice residue protein was hydrolyzed by different protease,the degree of hydrolysis and inhibition of ACE activity as indexes,to determine which protease was the best.Five-factor orthogonal experiment was taken to design the optimized hydrolysis conditions of rice residue protein with alcalase,the ACE inhibition rate and degree of hydrolysis as indexes. The alkaline protease hydrolyze of rice residue protein conditions were: substrate concentration 4%, pH9.2, temperature 55℃, ratio of alcalase to rice residue protein with E:S 2%, by single factor experiment to determine the best time for five hours. To determine the residue peptide of ACE inhibition rate under the different degree of hydrolysis found that the degree of hydrolysis and the ACE inhibition rate is not directly related to each other.Use the hollow fiber ultrafiltration membrane of 10kDa and 3kDa to isolated the unrefined peptide of rice residue.Then the high performance liquid chromatography was used to measure the ACE inhibition rate of rice residue peptide. The result was that the ACE inhibitory rate of rice residue peptide could reach 96.15% after 10kDa ultrafiltration membrane. Determined industrial production is only required once ultrafiltration.Studied the properties of peptide such as solubility,emulsibility and emulsion stability,foamability and foaming stability in different pH conditions,the function of promoting activity of yeast fermentation activity and amino acid composition.The result showed that:rice residue peptide has favorable solubility, not precipitated at the isoelectric point,it can be used as a nitrogen material to promote barm fermentation. After rice protein residue hydrolysated by enzyme,the hydrophobic amino acids and lysine increased 10 times more than rice residue protein,greatly improved the proportion model of amino acids.Its molecular weight was determined that hydrolysis by the alkaline protease of rice residue peptide are composited by low molecular weight peptide and molecular weight which are mainly distributed in the range of 297-573Da.Initially set up the best process of production of ACE inhibitory peptide: rice residue protein→pretreatment→protease solution→hydrolyzation→enzyme deactivation→centrifugation→.supernatant leaching→desalination→product. The process desalinated directly to the hydrolyzation can shorten the production of ACE inhibitory peptide ,and reduce the loss of protein and increase the ACE inhibition rate ,in line with industrial production requirements.