Study On Aqueous Enzymatic Extraction Of Oil And The Utilization Of Protein From Sunflower Seed

sunflower seed was an oil corn with high nutritional value,but this resource was not sufficiently developed. The aqueous enzymatic extraction oil and the utilization of defatted sunflower meal were studied with the high oil sunflower seed as raw material, which to provide theoretical and practical foundation of comprehensive utilization of sunflower seed. At first, the aqueous enzymatic extraction technology was studied. a continuous stirred tank membrane reactor(CSTMR) system was applied to the aqueous enzymatic extraction of sunflower seed oil, which decreases the production inhibition in the enzymatic hydrolysis process and increase reaction rate. The operation conditions were established, and influences of buffer pH, the temperature, time of hydrothermal treatment on yield of free oil were studied. The results showed that a high yield of free oil was obtained when sunflower seed was treated by hydrothermal treatment at 110℃for 60min in pH4.8 citrate buffer. The optimum conditions of extraction sunflower seed oil were determined by condition test and response surface analysis test. 89.8% free oil was obtained when sunflower seed was hydrolyzed at following conditions: enzyme amount: 2% (W/W), temperature: 50℃, time: 5.5h, dilution ratio: 1/8 (W/W).The influences of hydrothermal treatment and enzymatic hydrolysis on the damage of cell structure during the process of aqueous enzymatic extraction were studied with microphotograph of safranin stained technology. The results exhibited that the seed cell structure was destroyed during the mentioned process. Microphotograph of sudanⅢstained technology was used to research of the oil releasing process, which showed that it was very easy to release oil from enzymatic hydrolysis seed. All the research results mentioned above, in a microstructure standard, suggested that the aqueous enzymatic extraction technology of sunflower seed oil was feasible.The influence of aqueous enzymatic extraction on the quality of sunflower seed oil was also studied. The results showed that the temperature, time of hydrothermal treatment and pH of buffer had no influence on the color. The value of acid decreased from 2.17 to 1.98 mgKOH/g, while peroxide value varied from 1.36 to 2.53 meq/kg, according to the pH value increased from 3 to 7. The temperature and time of hydrothermal treatment had a great effect on the value of acid and peroxide value. Although hydrolysis process last 5h, it had no influence on the color, and the value of acid, peroxide and fatty acid content had rarely been affected by hydrolysis process.Sunflower isolated proteins, sunflower globular proteins and sunflower albumins were prepared from the defatted sunflower meal. Compared with soybean isolated proteins, the structure, function and physiochemical properties of sunflower proteins were investigated. The results showed that sunflower concentrated protein and isolated proteins have lowest solubility when pH value was 5, while sunflower globular proteins have lowest solubility when pH value was 4. Functional properties of sunflower isolated proteins were better or close to those of soybean isolated proteins, apart from the water absorption capacity of sunflower isolated protein was lower than that of soybean isolated proteins. The fat absorption capacity, the foam formation and foam stability, the emulsification activity and emulsification stability of sunflower isolated proteins were all higher than that of soybean isolated proteins, especially emulsification activity of sunflower globular proteins was very good.Sunflower isolated proteins showed five fractions by gel filtration and three major fractions having relatively molecular weights of 380,000,100,000 and 27,000. 11S globular proteins were the major fractions of sunflower isolated proteins. It was found that 10 major bands and 2 minor bands in sunflower globulins while sunflower albumins have 4 major bands and some minor bands by gel electrophoresis. The relatively molecular weight of the major bands of sunflower globular proteins were 53,500,42,600,39,500,33,200,30,800,26,500,24,000,22,500,20,8kDa和19.200. SDS-PAGE of sunflower isolated proteins found that there more bands than total bands of 11S globulins and 2S albumins. It indicated that sunflower isolated proteins had 7S globular proteins and other proteins apart from the 11S globular proteins and 2S albumin proteins. CD showed that the major structures of sunflower globular proteins and sunflower albumin proteins wereβ-sheet structure and random coil. Sunflower protein isβ- sheet type protein. DSC showed that the denaturation temperature of 11S sunflower globulins powder and 2S sunflower albumins powder were 123.5℃and 122.8℃respectively, sunflower proteins had high denaturation temperature. The fluorescence emission spectrum of the 11S sunflower globulins and 2S sunflower albumins gave a maximum at 345nm and 340nm. It indicated a greater contribution of tryptophan residues.Hydrolyzation of sunflower proteins with Alcalase, Protamex and Flavourzyme were studied. Taking DH, the soluble protein content and antioxidative activity of the hydrolysate as criteria, suitable conditions of sunflower proteins hydrolyzed with each enzyme were obtained. The molecular weight distribution of polypeptides in the hydrolysate processed with the three kinds of enzymes at different hydrolysis time was determined by gel chromatography. The results showed that relatively molecular weight mainly distributed from 590 to 2,975 when sunflower proteins hydrolysate was prepared with alcalase for 1h.Accordingly, the relatively molecular weight mainly distributed from 370 to 4,226 when it was prepared with protamex. However, when sunflower proteins was treated with flavourzyme for 1h, the relatively molecular weight mainly distributed from 370 to 5,117. One antioxidative peptide was obtained from the hydrolysate prepared with flavourzyme for 1h by ultrafiltration, ion exchange chromatography, gel chromatography and reversed phase chromatograpy methods. Amino acid sequences was determined by mass spectrograph analysis, which was Ala-Cys-Ala-His-Asp-Lys-Val.Antioxodative activity of this polypeptides was 79.6U/mL, which was a new polypeptide.Neurospora sitophilo was applied to the fermentation of the defatted sunflower meal to produce the antioxidative peptide. The cultivation base content and the fermentation operation condition were optimized. The gel electrophoresis of the fermentation product soaping liquid and the molecular weight distribution of the peptide were also studied. A lot of antioxidative products were found in the soaping liquid, which relatively molecular weight mainly distributed from 3,396 to 166 .