Preparation Of Anti-Angiotensin Converting Enzyme Peptides From Pork Ham And Stability Analysis

Angiotensin converting enzyme inhibitory peptides(ACE inhibitory peptides)can combine with ACE to regulate blood pressure.Pork ham is a kind of animal food with high protein content.Currently,pork ham,as a convenient and nutritious fast consumable food,has a high consumption.However,due to certain restrictions in processing technology,the nutritional value of pork ham has not been fully developed,which leads to the reduction of the added value of pork ham and the waste of protein resources.In this study,the extraction,separation and purification process of ACE inhibitory peptides derived from pork ham were studied,as well as the the amino acid sequence and stability of ACE inhibitory peptides of pork ham were evaluated.Some main conclusions were summarized as follows:In this experiment,pork ham was used as raw material to prepare ACE inhibitory peptide by protease hydrolysis.Firstly,according to the inhibition rate of ACE,the hydrolysate of pork ham hydrolyzed by alkaline protease had the strongest ACE inhibition activity.The effects of alkaline protease dosage,enzymatic hydrolysis temperature and p H on the inhibition of ACE activity of hydrolysate were studied.The reaction conditions were optimized by response surface center combination test.The optimal enzymatic hydrolysis process for preparing ACE inhibitory peptides from pork ham hydrolyzed by alkaline protease was obtained under 2.5 h.The optimal enzymatic hydrolysis conditions were as follows: enzymatic dosage 2U/mg,enzymatic hydrolysis temperature 56? and enzymatic p H 9.0.The alkali hydrolysates of pork ham were separated on ultrafiltration membrane according to cut off weight of 3KDa and 1KDa.The ultrafilter(<1KDa)showed the highest ACE inhibitory rate(79.43%)was futher sepearted into three fractions W1,W2 and W3 through DEAE-ion exchange chromatography.The fraction of W3(82.1%)had stronger ACE inhibitory rate than the other two fractions(W1 and W2)at the same concentration of 20 mg/m L,and further isolated into two sub-fractions(W3-1 and W3-2)through Sephadex G15 filtration chromatography.The sub-fraction of W3-2(89.1%)with stronger activity on inhibition of ACE rate was purified into five peaks of W3-2-1,W3-2-2,W3-2-3,W3-2-4 and W3-2-5 using RP-HPLC.The peak of W3-2-5(95.1%)exhibited the strongest ACE inhibitory rate than other peaks were multiplely collected and used for structure identification and stability analysis.Amino acid sequence of ACE inhibitory peptide in the target peak of W3-2-5 was identified as Asp-Tyr-Arg-Leu-Lys by N-terminal sequencing.Furthermore,the effects of heating temperature and time,and digestive enzymes on the activity of the ACE inhibitory peptide Asp-Tyr-Arg-Leu-Lys were investigated.Results showed that this peptide had the strongest ACE inhibitory rate(88.13%)at the temperature of 50?.In addition,the ACE inhibitory rate of Asp-Tyr-Arg-Leu-Lys was increased with prolonged thermal time and the ACE inhibitory rate remained 84.57% after heated for 60 min at 50?.The peptide Asp-Tyr-Arg-Leu-Lys was stalbe in the p H range of 2-10,and the highest ACE inhibitory rate was observed at p H 8.Also,its ACE inhibitory rate kept stalbe after hydrolysis under in vitro digestive enzymes.These results could provide useful suggestions for subsequent animal experiments.