| In this work, oil, protein and Tannin extract of Cornus officinalis seed were prepared and characterise. Oil content and protein content of Cornus officinalis core was as high as 40% and 30%, respectively, which made Cornus officinalis core being the high-quality source of plant oil and protein. The shells of Cornus officinalis seed were rich in Tannin extract with content being 13.32%. After separation of cores and shells, picking up the oil and protein from the cores and recovering Tannin extract from the shells, which achieved the comprehensive utilization of Cornus officinalis seed. Firstly, Cornus officinalis core oil was prepared by ultrasonic-assisted solvent extraction, cold pressing and extraction of CO2 SFE, respectively. Physical and chemical indicators, fatty acid composition and oxidation stability of Cornus officinalis core oil under optimum preparation conditions were detected and analyzed. Secondly, processing conditions of Tannin extract prepared by solvent extraction, stability and part of physical and chemical properties of Tannin extract were studied. The purity of Tannin extract under optimum preparation conditions was determined by Spectrophotometric methods. Finally, Cornus officinalis seed protein was prepared by the method of alkali-soluble and acid precipitation and glucoamylase assisting. Cornus officinalis seed protein was hydrolyzed by alkaline protease. Amino acids of Cornus officinalis seed protein with different degree of hydrolysis were compared. The main research results were as follows:1. Response surface methods were used to optimize extraction of CO2 SFE, ultrasonic-assisted solvent extraction and cold pressing to prepare Cornus officinalis core oil, respectively. The optimum conditions of Cornus officinalis core oil prepared by ultrasonic-assisted solvent extraction were that liquid-solid ratio 14:1(mL/g), extraction temperature 53 ℃, and extraction time 40 min. The yield of oil under these conditions was 41.78 %. The optimum conditions of Cornus officinalis core oil prepared by cold pressing were that rotating speed 34(r/min), pressing temperature 49 ℃, and pressing pressure 4.8 MPa. The yield of oil under these conditions was 39.78%. The optimum conditions of Cornus officinalis core oil prepared by extraction of CO2 SFE were that extraction pressure 39 MPa, extraction temperature 39 ℃, and extraction time 2.7 h. The yield of oil under these conditions was 40.83%. Cold pressing was proved to be the best method to prepare Cornus officinalis core oil by comparing physical and chemical indicators, fatty acid composition and oxidation stability of Cornus officinalis core oil by using the three methods. Studies has shown that Acid Value of Cornus officinalis core oil under cold pressing was 1.85 mg KOH/g, Peroxide Value was 1.95 mmol/kg, Iodine Value was 103.56 g I2/100 g, content of water and volatiles was 0.12 %, content of unsaturated fatty acid of Cornus officinalis core oil was 87.56~88.19%, among which the content of oleic acid was 41.66~41.99%, the content of linoleic acid was 44.32~44.58%. Oxidation stability of Cornus officinalis core oil under cold pressing was in the middle compared with other two methods.2. Orthogonal design was used to optimize the method of solvent extraction to get Tannin extract. The optimum conditions of Tannin extract by solvent extraction were that liquid-solid ratio 4:1(m L/g), extraction temperature 80 ℃, extraction time 4 h, dosage of sodium sulfite 4%, raw material crushing degree 0.6 cm, and concentration of concentrate 20 °Bé. Tannin content of Tannin extract under these conditions was 11.97%, total solid content was 19.95%, insolubles content was 1.06%, non-tannin content was 6.96%, water content was 10.1%, p H was 5.2, and total color value was 13.9. Purity of tannins detected by Spectrophotometric methods was 64.99%, which could meet the needs of the markets basically. The total color value was used to evaluate the oxidation stability of Tannin extract. Results indicated that it is optimal to keep Tannin extract out of sun and under low temperature. Studies showed that total color value, Buffer index and viscosity index of Cornus officinalis Tannin extract were at low level, with excellent salting-out resistance and acid resistance abilitys, which has the similar properties as black wattle bark tannins.3. Response surface methods were used to optimize the method of alkali dissolution and enzyme hydrolysis to get Cornus officinalis seeds protein. Optimal conditions for the preparation by alkali dissolution and enzyme hydrolysis were that liquid-solid ratio 13:1, the amount of enzyme 0.04%, enzymatic hydrolysis time 44 min, and pH of enzymatic reaction 4.4. Verification tests were made and yield of protein under these conditions was 90.25%, which was close to the standard of protein isolate. Amino acids, TAA content and EAA/TAA of Cornus officinalis seed protein with different degree of hydrolysis were compared, which come to a conclusion that amino acids composition of Cornus officinalis seed protein was reasonable as it contained 8 kinds of EAA which human body needed. The optimum enzymatic hydrolysis time was determined to 40 min by taking the efficiency and energy consumption into account. Under this condition,degree of hydrolysis was 23.78%, TAA content was 700.25 mg/g, and EAA/TAA was 38%. |
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