Study On Separation, Preparation And Detection Method Of Effective Components From Oil Crops

Fats and proteins are the kinds of important raw materials of modern food industry. It is the most importantof oil-crop source for vegetable oil and protein, to ensure the efficient supply of vegetable oil and protein, to improve food structure and promote the development of aquaculture and processing. With the development of food industry, comprehensive utilization of oil crops resources are becoming the main direction and the development requirements, which are favorable to increase the added value of products, and reduce energy consumption of processing. Oilseed is the very complex biological material system including protein, fats and many kinds of secondary metabolites. It is necessary to improve efficient separation and detection technologies for the utilization of oil crops resources. In this thesis, it is mainly focused on the application of modern separation and detection technologies in oil processing in order to meet the demands of food, especially fats and protein. The main contents and results are summarized as follows:(1) Ultrasonication and ultrafiltration technology provides an efficient means of separation and enrichment for the food science. In this study, these technologies are applied in the extraction of rapeseed protein to improve the protein extraction efficiency. The presence of complex protein constituents and difficulties in extracting protein from rapeseed meal limit the application of rapeseed protein in food processing. However, double-low rapeseed (low erucic acid, low glucosinolate) protein is a type of complete protein that is of potential use in the food industry. Single factor experiments and analysis of the regression equation indicated that the optimal conditions for ultrasonic-assisted extraction were an ultrasonic power of 450 W, an ultrasonic treatment time of 84 min, a solid/liquid ratio of 1:24, a pH of 11.5 and an ultrasonic temperature of 35℃. under these optimized condition, the protein extraction efficiency was 76.83±2.53%, which increased by 35.43±1.84% comparising with the traditional water bath.The functional properties (oil adsorption ability, emulsifying capacity, foaming capacity and foam stability) of RPs, RP5.8 and RP3.6 were found to be better than those of soybean protein. The solubility of rapeseed protein indicated that a multistage precipitation method for extracting rapeseed protein was necessary. The results of this study provide useful indicators for rapeseed protein as a potential replacement for other proteins.(2) Nano-encapsulation technology has been widely used in food industry, especially in color, smell, taste, type, nutrition and health and safety. Phytosterol liposomes were prepared using the thin film method and used to encapsulate nattokinase (NK). In order to obtain a high encapsulation efficiency within the liposome, an orthogonal experiment (L9 (3)4) was applied to optimise the preparation conditions. The molar ratio of lecithin to phytosterols, NK activity and mass ratio of mannite to lecithin were the main factors that influenced the encapsulation efficiency of the liposomes. Based on the results of a single-factor test, these three factors were chosen for this study. We determined the optimum extraction conditions to be as follows:a molar ratio of lecithin to phytosterol of 2:1, NK activity of 2500U/mL and a mass ratio of mannite to lecithin of 3:1. Under these optimised conditions, an encapsulation efficiency of 65.25% was achieved, which agreed closely with the predicted result. Moreover, the zeta potential, size distribution and microstructure of the liposomes prepared were measured, and we found that the zeta potential was-(51±3) mV and the mean diameter was 194.1 nm. From the results of the scanning electron microscopy, we observed that the phytosterol liposomes were round and regular in shape and showed no aggregation.(3) Solid-phase microextraction (SPME), as a sample preparation technique, is widely applied in the flavor of the food industry. With the improvement of living quality, high-oleic peanuts have drawn people's attention. Increasing oleic acid content of peanut oil should be desired for both improved shelf life and potential health benefits. The flavor of peanut products is important to the overall acceptance of these products by consumers. Volatile components of peanut oils were analyzed and identified by solid-phase microextraction/gas chromatograph/mass spectrometer (SPME-GC-MS). First, influence of SPME extraction, such as, fiber coating, extraction temperature and extraction time, was optimized. Then volatile compounds in high-oleic and normal peanut oils was profiled following three different processing method, such as roasting, boiling and roasting, and roasting by microwave-assisted. Principal components analysis (PCA) was used to analyze volatile components in peanut oils of different cultivars. The results showed that there were obviously differences about the volatile components between high-oleic and normal peanuts. Among different processing method of peanuts, clear separation on volatile components was observed. The same kind of genotype had the similar flavor characteristics. Moreover, different processing methods had significant effect on volatile components in peanut oils.(4) Mass spectrometry (MS) has been widely applied in the analysis and detection of lipid and its metabolites. In this study, hydroperoxides of lipid oxidation are analyzed by MS. Lipid oxidation is the main cause of quality deterioration of oil-based food. Hydroperoxides are the original products of lipid oxidation, which was separated and analyzed by high performance liquid chromatography-ion trap tandem mass spectrometry (HPLC-ESI-MS-/MS) with the multiple reaction mode (MRM). Effection of fatty acids compositions and treatment methods of high-oleic and normal peanuts on lipoxygenase and hydroperoxides were investigated. Results Linearity was found in the range of 5.0-200 ng/mL (r> 0.99) with the rapid separation and detection methods of hydroperoxides using HPLC-ESI-MS/MS. Relationship of fatty acids compositions (oleic acid, linoleic acid and linolenic acid content), lipoxygenase activity and hydroperoxide content was clarified by using canonical correlation analysis. Oleic acid content had a negative correlation with lipoxygenase activity soaked by alkaline solution. The amounts of peroxides had a positive correlation with linoleic acid content. And the content of 13(s)-HPOT had negative correlation with oleic acid content. These results were consistent with the antioxidation of high-oleic peanuts.Oilseeds contain complex compositions, not only including high content protein and fats, but also having low content functional components. Moreover, many compositions have similar structure and properties, and these lead to the difficulties of extraction and purification technologies. Extraction, separation, identification and functional components and product development technologies of effective components are domestic and overseas hot spots and difficult points. Application of modern separation and detection technology in the processing of oil crops has a great signality to insure the whole agricultural sustainable development, increase farmers income, and improve people's living standard.