Study On The Technology And Quality Evaluation Of Oil Production By Microwave Pretreatment Press Of Xanthoceras Sorbifolia

Xanthoceras sorbifolia is a special woody oil plant in North China,which has high ecological,edible,medicinal,energy and ornamental value.Xanthoceras sorbifolia oil is rich in tocopherol,phytosterols,and mineral elements,and the unsaturated fatty acid content in the oil is as high as 90%or more.It is a high-quality edible oil.At present,the shortage of edible oil in our country has become more and more serious.It is urgent to increase the supply of high-quality edible vegetable oils by vigorously developing woody oil industry such as Xanthoceras.In this study,the seed kernel of Xanthoceras sorbifolia was used as raw material,which was pretreated by microwave technology,and the oil of Xanthoceras sorbifolia sorbifolia was made by mechanical pressing.We explored the effects of different microwave treatment conditions on the physicochemical properties,nutritional quality and antioxidant activity of Xanthoceras oleifera oil.Then a new technology of microwave pretreatment for pressing Xanthoceras sorbifolia oil was established,and the quality changes of Xanthoceras sorbifolia oil without microwave treatment and microwave treatment during storage were compared.The main research results are as follows:1.Response surface methodology?RSM?was used to optimize the process of microwave pretreatment for pressing Xanthoceras sorbifolia oil.Based on a single factor,the Box-Behnken test design was performed to optimize the oil yield of Xanthoceras sorbifolia,and the regression model of the relationship between the oil yield of Xanthoceras sorbifolia and raw material moisture,kernel shell ratio,microwave time and microwave power was obtained,which is Y=56.38+2.14A+3.46B-0.97C-0.42D-0.14AB-0.24AC-0.064AD+0.12BC+0.23BD-0.12CD-3.60A²-5.78B²-3.31C²-1.28D².It was proved by validation that the model can be used to predict the oil yield of pressed Xanthoceras sorbifolia oil by microwave pretreatment.The final optimal process conditions are:raw material moisture 8.3%,kernel-shell ratio 9:1,microwave time 5.4 min,microwave power 960 W.Under this process condition,the oil yield of Xanthoceras sorbifolia was 56.79%,increased by 10.42%compared with the oil yield of directly pressed Xanthoceras sorbifolia?46.37%?.2.The effects of microwave pretreatment on the physicochemical properties,nutritional quality and antioxidant capacity of Xanthoceras sorbifolia oil.In the experiment,the seeds of Xanthoceras sorbifolia were pretreated by microwave under different conditions.Observation by transmission electron microscopy revealed that the seed kernel cells without microwave treatment were neatly arranged,the cell walls were smooth and complete,the oil body membrane was clear and complete,and the oil and protein bodies were separated by the oil body membrane.While after microwave treatment,the cell wall of the seed kernel swelled and deformed,the oil body membrane was destroyed and the oil was gathered,which is beneficial to the overflow of oil.Appropriate microwave pretreatment destroyed the internal structure of seed kernels and allowed water to evaporate from the inside,which increased the path for oil spillage and helped to improve the oil yield of Xanthoceras sorbifolia.However,excessive microwave treatment will cause the collapse of seed structure of Xanthoceras sorbifolia,and it is easy to be squeezed into a powder to block the oil passage during pressing,resulting in a decrease in the oil yield of the raw material.By measuring the physicochemical properties and nutritional quality of Xanthoceras sorbifolia oil under different microwave treatment conditions,it was found that the microwave pretreatment had significant effects on the acid value,peroxide value,and content of phospholipids,total flavonoids,tocopherols,and phytosterols of Xanthoceras sorbifolia oil.Proper microwave treatment was helpful to increase the nutrient content of Xanthoceras sorbifolia oil,but when the microwave time was too long,the nutrient components will be decomposed and the content will be reduced.Microwave pretreatment had no significant effect on the fatty acid composition of Xanthoceras sorbifolia oil.It was found that microwave pretreatment was helpful to improve the antioxidant capacity of Xanthoceras sorbifolia oil,and the correlation analysis showed that the induction time of oxidation of Xanthoceras sorbifolia oil was positively correlated with the content of tocopherol,flavone,phytosterol and phospholipid in the oil.3.Study on the quality change of Xanthoceras sorbifolia oil during storage.Three kinds of Xanthoceras oleifera oil samples were studied by accelerated oxidation experiments at 60?and the results showed that AV,POV,P-AV,K₂₃₂,K₂₇₀,tocopherol content,and fatty acid composition all changed significantly during the process of storage.POV and K₂₃₂ increased rapidly in the early and late stage,and grew moderately in the middle stage.After 50 days,the POV of Xanthoceras oleifera oil increased from 0.16 mmol/kg to 14 mmol/kg,and K₂₃₂ increased from 0.9 to 4.7.AV,P-AV and K₂₇₀ grew continuously in the experiment.The content of tocopherol,the initial temperature of oxidation and the induction time of oxidation decreased rapidly in the early and late stage of the experiment,and decreased slowly in the middle stage.In the experiment,the content of saturated fatty acids increased while the unsaturated fatty acids decreased,the content of oleic acid increased while the linoleic acid decreased,and the content of polyunsaturated fatty acids decreased significantly.The correlation analysis showed that the oxidation stability of Xanthoceras sorbifolia oil during storage was positively correlated with tocopherol content,negatively correlated with POV,AV,P-AV,K₂₇₀ and K₂₃₂,and positively correlated with tocopherol content,AV,P-AV,K₂₃₂ and K₂₇₀.