Effect Of Pretreatment With Microwave On Quality Of Cold-pressed Oil From Rapeseed

China is the rape production and the consuming country, rape is one of a largest vegetable oil source in our country. The yearly average area of rape planting and the ultimate production in our country rank first in the world.Using technology for clod pressing to take the rapeseed oil, can avoid heating the fuel oils too much and the excessive chemical treatments, making the quality of rapeseed oil have the corresponding enhancement. However,owing to the existence of cold crushing poor oxidation stability, low oil and other technical barriers, so this study will process advanced microwave pre-treatment technology to apply to the cold-pressed rapeseed oil for the first time, and on the microwave Preparation of rapeseed oil cold pressed rapeseed cold-pressed rapeseed oil on the quality of a systematic study of the quality of China’s development and utilization of rapeseed oil to provide a theoretical foundation and experimental data. The findings are as follows:1. The initial moisture content, the microwave time and the microwave power to the rapeseed oil extraction rate and main physics and chemistry target of the rapeseed oil influence have been studied. The experiment discovered that the microwave processes has little influence on the acid value of raeepesd oil; peroxide value increased firstly and then decreased,;the maximum value of peroxide value approximately doubles.The lower initial moisture content is,the higher oil extraction rate is. but the rapeseed oil luster deepens is quicker, the shorter the time required to produce precipitation in heating tests, after microwave processing,when the rapeseed moisture content is less than 4%,it starts to smell burnt taste.Therefore, the moisture content should be controlled in an appropriate context; A microwave process time is longer,the oil extraction rate is higher, the rapeseed oil color is deeper, after processing a period, the heating test has the precipitation. A microwave power is greater,the oil extraction rate is higher, the rapeseed oil luster deepens is quicker, the time that the precipitation produces in the heating test obviously reduces, microwave power is not suitable to oversize.2. The initial moisture content, the microwave time and the microwave power to the main nutritive index of rapeseed oil influence have been studied. Initial moisture content have different effect on the high and low erucic acid content of two varieties of rapeseed oil in the chlorophyll, polyphenols, vitamin E and phytosterols content. Along with the microwave process time’s extension, the chlorophyll, the polyphenol and the phytosterin content in the rapeseed oil obviously increase, but the Vitamin E content presents increases first, then reduces. The microwave power has remarkable effect on the chlorophyll and the polyphenol content Along with the microwave power’s increasing, the speed of the chlorophyll and the polyphenol content increasing speeds up; microwave power had no significant effect on vitamin E and phytosterols. but when the microwave power is large, the content of vitamin E and phytosterols in rapeseed oil is relatively high. Microwave treatment had no significant effect on the composition of rapeseed oil fatty acid, and the anti-form fatty acid production has not been examined.3. A systemic research has been made on the influence of the microwave processing to the rapeseed oil oxidation stability. The research discovered that microwave processing can obviously enhance the rapeseed oil the oxidation stability. Along with the time of the microwave processing extension, the oxidation stability obviously increases;the initial moisture content has remarkable effect on the oxidation stability.the initial moisture content is low,the rapeseed oil oxidation stability is high. The microwave power also has remarkable influence on the oxidation stability.The microwave power is big, the oxidation stability increases quickly, but should not be to high. The chlorophyll, the polyphenol, Vitamin E and the phytosterin are related to the oxidation stability of rapeseed oil. Among them, vitamin E and oxidative stability exist remarkable inverse correlation.4. The microwave to the rapeseed oil in the sulfur glucoside degradation product influence has been studied. The findings showed that in rapeseed oil sulfur glucoside degradation product compound primarily by mustard oil and nitrile class. The sulfur glucoside degradation product’s type and the content change along with the microwave process time. Which both reduces first and then increases with the microwave process time’s extension, the content and the type falls to lowly when microwave processing has lasted for 4min. The main sulfur glucoside degradation product is mustard oil when the time of microwave processing is short. when 4min,mustard oil and nitrile class content is equal. along with the time enlarging, the main degradation product is nitrile class. The total quantity of oil mustard has accounted for 94% in rapeseed oil which has not been microwave processed. In the microwave processing the proportion accounting for reduces gradually, when 7min the quantity reduces to 13.45%, but the total quantity of the nitrile class accounts for from intial 6% to 86.55%.