| The dissertation is the partial contents of the fund project of National High-tech R&D Program of China(Program 863)(No. 2008AA10Z308) “Research on the Smart Structure of Protein-based Edible Biological Polymer Film” and the project of National Key Technology Research and Development Program of the Ministry of Science and Technology of China(2015BAD16B05) “Development of Antiseptic and Preserving New Type of Logistics Packaging Materials”.Sunflower seed husk is the shell(husk) of short oval achene seed of Helianthus annuus(Helianthus annuus), a therophyte belonging to Helianthus, Asteraceae. As a by-product of agriculture product processing, the annual output of sunflower seed husk is about 700,000 tons. And most of them will be disposed as waste which will cause resources waste and environmental pollution. Therefore, how to rationally develop and utilize the resources has become a hot topic that concerned by the public. On the other hand, due to the enhancement of awareness of food safety and environmental protection, food packaging materials using natural macromolecule material as the base material has become a research hotspot.The dissertation takes sunflower seed husk as the raw material, extracts sunflower shell cellulose by adopting alkali extracting, performs technologic condition optimization and mathematical model test by utilizing Box-Behnken response surface test method and carries out analysis validation on the results to obtain the optimal technology parameters extracted from cellulose: 15.83 m L.g-1 of extracting solution, 9.96% of extraction solution mass fraction, 70.73 min of extraction time, 48.58? of extraction temperature and 46.30% of cellulose yield. The dissertation performed modification treatment for sunflower shell cellulose by adopting microwave, ultrasonic collaborative technology, and studied the impact of microwave power on the oil absorption performance, water-holding power, water-absorbable and swellable properties, particle size, specific surface area and microstructure of cellulose. When the microwave power is 300 W, the water-absorbable property will reach the maximum value 3.91 g g-1; the water-absorbable and swellable properties of cellulose will increase along with the rising of microwave power and will tend to stable. When the microwave power is 400 w, the water-absorbable property will reach 12.12 g g-1; the volume mean diameter of cellulose will decrease along the increasing of microwave power, and the specific surface area will gradually increase with the increasing of microwave power; the analysis result of Fourier Transform Infrared Spectroscopy(FTIR) shows that the cellulose molecules after transformation still show basic chemical structure of cellulose; X-Ray Diffraction(XRD) analysis results show that the modified cellulose crystal type is not subject to any change, and belongs to typical cellulose type I crystal structure and crystallinity decreasing; the analysis result of Field Emission Scanning Electron Microscope(SEM) indicates that the modified cellulose surface will become rough with crack and grooves. The structure will become more loose.Sunflower shell nanocellulose(NCC) is prepared by sulphuric acid hydrolysis method with sunflower shell cellulose as the raw material. The optimum conditions for preparation of NCC are determined through single factor experiment and Box-Behnken test response surface method: 42.00? of acid solution temperature, 83.71 min of acid solution duration, 59.97% of sulphuric acid concentration, 12.33:1 of liquid to solid ratio, and 31.31% of NCC yield ratio. NCC ultrastructure is represented by adopting Transmission Electron Microscope(TEM), Fourier Transform Infrared Spectroscopy(FTIR) and X-Ray Diffraction(XRD). The analysis results show that the diameter of NCC prepared by sulfuric acid hydrolyzation is 10~30nm. It presents rodlike structure with a length of 150~300nm. Intramolecular and intermolecular hydrogen bonds of molecular structure are enhanced belonging to typical of Cellulose ? Type crystal structure with a crystallinity degree of 65.85%; relying on the thermal property representation with a differential scanning calorimeter(DSC), the results indicate that the thermal decomposition process of NCC is a direct solid- phase transition process with high heat conduction property.The edible film is prepared by taking NCC as filler and blending chitosan(CS) and soy protein isolate(SPI). On the basis of single factor experiment, the synthetic score S of edible film performance indicators is determined by adopting principal component analysis and membership degree scoring method. Perform optimization with S as response value utilizing Box-Behnken response surface method. When film-forming material weight ratio is 1.25:0.75:2, the PH value is 3.59, the concentration of glycerine mass is 0.02g/m L, the synthetic score S of edible film performance indicators is 0.62. Under such circumstance, the tensile strength of edible film is 19.38 MPa, the elongation at break is 14.17%, the water vapor permeability is 1.03×10-13 g.(cm-1·s-1·Pa-1), and the oxygen permeability is 0.52×10-5cm3.(m-2.d-1.Pa-1). The edible film SEM and FTIR analysis show that film-forming materials have high compatibility.The dissertation performed modification treatment for edible film membrane liquid by adopting microwave, ultrasonic collaborative technology on CS-SPI and NCC-CS-SPI. It studied the impact of microwave power on the edible film mechanical properties(tensile TS, elongation at break E)and barrier properties(water vapor permeability WVP and oxygen permeability OP). The results indicate that the mechanical and barrier performance of the edible film after modification treatment can be improved. In addition, it can be seen from SEM and FTIR analysis results that the modification can promote the formation of intermolecular and intramolecular hydrogen bonding, and can further improve the compatibility of film-forming material.The hydrophobic grouping of stearic acid molecules can be stem grafted onto NCC-CS-SPI edible film surface in order to improve the water resistance performance of edible film. It studied the impact of microwave power and microwave time on mechanical properties of edible film(TS, E)and water resistance performance(WVP). When the microwave time is the same, and the microwave power is 300 W, the water vapor permeability coefficient of edible film will reach the minimum value of 0.38×10-13g·(cm-1·s-1·Pa-1); and when the microwave power is the same and the microwave time is 10 min., the water vapor permeability coefficient of edible film will reach the minimum value of 0.42×10-13g·(cm-1·s-1·Pa-1); however, the impact of microwave power and microwave time on the mechanical properties is not obvious. Molecular structure and contact angle can be analyzed by utilizing FTIR and interfacial tension of contact angle measurement instrument. The results show that-C=O stretch vibration absorption spectra will occur at the wave of 1728cm-1 after hydrophobic modification. Introduce the-OOCR peptide reactive group to edible film molecular. In addition,-OH stretching vibration absorption peak intensity will decrease at the wave of 3380cm-1 and 895cm-1. Other functional groups are not subject to change in molecular structure of edible film before and after hydrophobic modification. Appropriate modification can make edible film presents hydrophobicity.Edible film membrane liquid is applied on room temperature coating preservation on strawberry. The change conditions on strawberry weightlessness rate, decay rate, respiration intensity, hardness, color, Vc content, soluble solids content, titratable acid content, activity of polyphenol oxidase, peroxidase activity and other indicators show that coating treatment can reduce strawberry nutrition loss, delay the mature or after-ripening and further prolong the storage period and ensure excellent preservation effects. |
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