Study On Extraction Of Chlorogenic Acid And Preparation Of Functional Peptides From Sunflower Seeds

The sunflower seeds as raw materials in the paper, chlorogenic acid was extracted, and then the sunflower isolated proteins (SIP) were extracted by alkali extraction and acid precipitation, the sunflower seed peptides (SSP) were prepared by the ways of composite enzymatic hydrolysis and ultrasonic technology, and refined using membrane separation technique. The functions of SSP in inhibiting nitrosation reaction and the hemolysis of mice red blood cell, and preventing alcohol-induced liver injury were systematic studied. The results showed:1. The conditions of extracting chlorogenic acid (CHA) by ethanol from defatted sunflower seed powder were determined by single factor and orthogonal experiments, the optimum conditions were as-following: temperature 40℃,50% aqueous alcohol, pH6.0, a ratio of material to solvent 1:20, time 2 hours, two-step extraction. The yield was 2.46%. CHA was qualitative analysed used thin layer chromatographic (TLC) methods with butanol-acetic acid-H2O(4:2:5) as the mobile phase. It was found that samples had the same spot in accord with CHA standard, so it showed samples contained chlorogenic acid.2. The sunflower isolated proteins (SIP) were extracted by alkali extraction and acid precipitation. The SIP was hydrolyzed by two enzymes of alkaline protease and complex acid proteases step by step to produce low mocular SSP. The hydrolysis efficiency was improved by combinating with ultrasonic technology. The tricine-SDS-PAGE electrophoresis pattern and SephadexG-25 gel chromatography analysis pattern of SSP showed the main components were below 3400Da, and the SSP of below 3000Da reached 78.41%.3. Through ultrafiltration membrane with different MWCO(Molecular Weight Cutoff) 4000 and 2000Da in turn under the condition of room temperature,0.3MPa, concentration of 2% and pH6.0, SSP was separated into three different components:SSP1 with the molecular weight(MW) above 4000Da,SSP2 with MW between 4000 and 2000Da and SSP3 with MW below 2000Da. Then the peptides were treatmented by nanofiltration(NF) and reverse osmosis(RO), results showed that the desalting effect of NF and RO were better, but the loss rate of total nitrogen of RO was higher, while the loss rate of total nitrogen of NF was 12.17%. Taken together, NF was only choosed to purify peptides.4.The functions of SSP1,SSP2 and SSP3 in scavenging nitrite,disconnecting N-nitrosodiethylamine (NDEA) synthesis,inhibiting the hemolysis of red blood cells by itself and H2O2 induced hemolysis in vitro were researched. The results showed that SSP2 with a molecular weight between 4000Da and 2000Da had the strongest activity, it was the ideal raw materials of making food-borne anti-cancer foods and antioxidant.5. SSP2 was fed to study the effect on preventing chronic alcohol-induced liver injury of mice. The results showed that the content of MDA significantly decreases and the content of GSH significantly increases in liver and the activity of ALT and AST significantly decreases in serum. There was significant difference (p<0.05) as compared with the model group. It showed that SSP2 had significantly protective effects on alcoholic liver injury.