Aqueous Enzymatic Extraction Of Sunflower Seeds Oil And Recovery Protein

Sunflower seed contains a large amount of oil, especially the unsaturated fatty acid (85~90%) of which over 60% is linoleic acid. Therefore the sunflower seeds oil is called"advanced nutritious oil", and sold well on the international market. Aqueous enzymatic extraction technology has been studied for a long time. The process of extraction is not similar for different oilseeds. In this dissertation, the suitable process and the optimum extraction conditions for sunflower seeds oil were studied, and then the demulsification method, the recovery of sunflower seeds protein from the aqueous solution and the function of this protein were researched.The sunflower seeds oil was produced using enzymatic hydrolysis method. Dehulled sunflower seeds were ground without water, and then added into pH 4.8, 0.05 mol/L citrate buffer, water/seeds ratio was 5:1(w/w). The enzymatic treatment was performed at 50℃with 2.5% the mixture of a cellulase for 7 h with stirring (250 r/min). After the first centrifugation step, emulsion was separated and recentrifuged (8000 g) to get more oil. The oil extractability was about 90%.In order to enhance the oil yield, the demulsification methods have been studied. Comparing different demulsification methods, such as microwave irradiation, heating, freezing, standing and ultrasonic method, the results showed the effect of heating to be the best. The optimum conditions are heating the emulsion at 100℃for 15 min, and then centrifuging it at 8000 r/min for 20 min, the ratio of demulsification was 63.16%. The quality of the sunflower seeds oil was mensurated too. The fatty acid constitution of the sunflower seeds oil was up to the international standard. Except the acid value, the oil with light color and good flavor was superior to the national grade four finished product of sunflower seeds oil.Sunflower seeds protein was extracted from the aqueous solution by water solution and alcohol sedimentation. The aqueous solution was filtrated, and then condensed until the concentration of solid substance got 13%, added 75% alcohol to sedimentate the protein. The ratio of the protein recovery and the chlorogenic acid removing were both over 80%.Determinations of some functional properties and the composition of sunflower seeds protein were also taken. The protein's denaturalization temperature is around 94℃, pI=4.5. The capacity of absorbing oil is better than that of soy isolate protein, but the capacity of absorbing water is worse than it. Compared with soy isolate protein, sunflower seeds protein had better emulsifying capacity and stability at low temperature. The foaming capacity of the sunflower seeds protein was good, but the foam was not stable. The amino acid composition of the protein was good with high content of glutamic acid. The sunflower seeds protein's structure was stable and SDS-PAGE revealed that albumin show six bands (51600,43000,37700,32500,21200 and 13800), globin show five bands (37700,34300,20000,15700 and 14400), and glutelin show only one band (14400).