Compared with retail prices of state-owned companies used in almost all existing studies,China’s refined oil wholesale prices of private enterprises and local refineries are more affected by the market and better ref...Compared with retail prices of state-owned companies used in almost all existing studies,China’s refined oil wholesale prices of private enterprises and local refineries are more affected by the market and better reflect the real supply-demand situation.For the first time,this paper applies own-monitored dailyfrequency wholesale prices of China’s private enterprises and local refineries during 2013-2020 to derive spillover effects of international crude oil prices on China’s refined oil prices through the VAR-BEKKGARCH(vector autoregression-Baba,Engle,Kraft,and Kroner-generalized autoregressive conditional heteroscedasticity)model,and then tries to forecast wholesale prices through the PCA-BP(principal component analysis-back propagation)neural network model.Results show that international crude oil prices have significant mean spillover and volatility spillover effects on China’s refined oil wholesale prices.Changes in crude oil prices are the Granger cause of changes in refined oil wholesale prices.With the improvement of China’s oil-pricing mechanism in 2016,the volatility spillover from the international crude oil market to China’s refined oil market gradually increases,and the BRENT price variation has an increasing impact on the refined oil wholesale price variation.The PCA-BP model could serve as a candidate tool for forecasting China’s refined oil wholesale prices.展开更多
Phytosterols,which are naturally occurring in plants,have excellent nutritional and health values on lowering both the blood cholesterol level and the risk of cardiovascular diseases.Edible oils are the main source of...Phytosterols,which are naturally occurring in plants,have excellent nutritional and health values on lowering both the blood cholesterol level and the risk of cardiovascular diseases.Edible oils are the main source of daily intake of phytosterols,whereas the properties of phytosterols may vary a lot depending on their sources.During the processing of edible oil including refining and frying,phytosterol's content fluctuates,which influences the properties of the final product.Phytosterols and their derivatives undergo physical migration between different phases and chemical conversion during the processing,which reduces the quality and the commercial value of edible oils.Therein,the loss of phytosterols is the major concern in the process of neutralization and deodorization.In addition,oxidation and thermal degradation of phytosterols occur simultaneously during frying,which also reduces the content of phytosterols.Nevertheless,the oil matrix has a promoting or an inhibitory effect on the thermal oxidation of phytosterols.Therefore,various efforts have been devoted to analyzing and improving the remaining contents of phytosterols in edible oil.Regardless of the processing method,temperature plays an important role in the loss of phytosterols.At present,themain analysismethods of phytosterols include gas chromatography and liquid chromatography,inwhich the pretreatment of different types of phytosterols is also a crucial step.This review focused on the following topics comprehensively:(i)the distribution of phytosterols in the oil-containing plants and edible oils during the refining processing;(ii)the pretreatment and analysis methods of various phytosterols(free phytosterols,phytosteryl fatty acid esters,phytosteryl glycosides and acylated phytosteryl glycosides);(iii)the variation of phytosterols in process of esterification and oxidation,storage and so on.The study also proposed that the investigation in the loss and safety of phytosterols during processing of the vegetable oils should be proceeded further in combination with efficient and accurate chromatography methods.展开更多
The article is the result of theoretical and experimental studies aimed at determining the structural groups of modern bituminous materials in order to assess the raw materials, production technology, rational directi...The article is the result of theoretical and experimental studies aimed at determining the structural groups of modern bituminous materials in order to assess the raw materials, production technology, rational directions for their use in construction, the road industry and waterproofing. Commercial oil bitumen, raw tars and heavy oil residues (semi-finished products) of oil refineries aimed at meeting large-tonnage needs have been studied. The assessment was carried out according to the group hydrocarbon composition, by liquid chromatography using model compounds. Comparative analysis showed a general trend for all studied samples of petroleum bitumen: low content of asphaltenes (from 3.9 to 23.9 wt.%), low content of resins (from 11 to 19.07 wt%), insufficient for the formation of stable structuring layers, and a significant content of aromatic hydrocarbons, including heavy aromatic compounds (more than 20 wt.%). An assumption was made about the influence of the origin and the structure obtained during the processing of asphaltenes and resins on the transition from one type of bituminous structure to another based on the lyophility of high-molecular group components. A comparative structural characteristic of heavy oil residues from gasoline and oil production is considered in comparison with bitumens of various viscosities. Recommendations are given on the technology of processing petroleum feedstock and the use of heavy oils in order to obtain a given bitumen structure for the production of rational bitumen products for construction and waterproofing.展开更多
Accurate sales prediction in filling stations is the basis to fill in the refined oil in time and avoid the outof-stock as much as possible.Considering the defect of great“lag”in the general time series model,this p...Accurate sales prediction in filling stations is the basis to fill in the refined oil in time and avoid the outof-stock as much as possible.Considering the defect of great“lag”in the general time series model,this paper summarizes the multiple factors that influence the oil sales and develops a multivariable long short-term memory(LSTM)neural network,with the hyper-parameters being improved by the genetic algorithm(GA).To further improve the prediction accuracy,the proposed LSTM neural network is generalized to bidirectional LSTM(Bi LSTM),in which the impact of future factors on present sales can be taken into account by backward training.Finally,different LSTM structures and genetic algorithm parameters are tested to discuss their impact on prediction accuracy.Results demonstrated that genetic algorithm improved Bi LSTM model is superior to extreme gradient boosting,ARIMA,and artificial neural network,having the highest accuracy of 89%.展开更多
In this study,the effects of chemical refining on the physicochemical indices,environmental pollutants,lipid functional groups,relaxation characteristics,fatty acid profiles,and triglyceride(TG)molecular species in cr...In this study,the effects of chemical refining on the physicochemical indices,environmental pollutants,lipid functional groups,relaxation characteristics,fatty acid profiles,and triglyceride(TG)molecular species in crude oil extracted from small fish in Mauritania were evaluated.The acid,peroxide,and iodine values of crude oil were identified as 5.52 mg KOH/g,1.73 meq/kg,and 200.78 g/100 g oil,respectively.After refining,these values were determined to be 0.29 mg KOH/g,0.76 meq/kg,and 210.80 g/100 g oil,respectively.The polychlorinated biphenyls and arsenic content of crude oil were identified as 32.30μg/kg and 1.00 mg/kg,respectively.After refining,these were not detected.The content of eicosapentaenoic acid(EPA)and docosahexaenoic acid(DHA)accounted for as much as 87.55%of the polyunsaturated fatty acids in the refined oil,indicating that high-quality fish oil is suitable as a food supplement.The correlation coefficient of the infrared spectra before and after refining was 0.968,and the relaxation time and peak shape data were almost similar before and after purification.Meanwhile,there were no significant differences(P≥0.05)in fatty acid profiles between the crude and refined oils,except for C16:0(P<0.01).Based on UPLC-Q E-MS/MS detection,137 TG molecules were identified in both crude and refined oils.Among the detected TG molecular species,64 contained EPA or DHA,which accounted for 46.83%and 46.00%of the total TG content in crude and refined oils,respectively.After refining,the content of the molecular species decreased by 31.95 mg/10 g,among which the three most variable molecular species were TG(16:0/18:1/22:6),(16:1/16:2/18:1),and(18:4/16:0/20:5),accounting for 29.26%of the decline of the molecular species.Overall,the refining process had little effect on the fatty acid profile and distribution of TG molecular species in fish oil.展开更多
Objectives:Polycyclic aromatic hydrocarbons(PAHs)and 3-monochloropropane-1,2-diol ester(3-MCPDE)were studied in camellia oil.It is important to study the changes in the content of PAHs and 3-MCPDE at different refinin...Objectives:Polycyclic aromatic hydrocarbons(PAHs)and 3-monochloropropane-1,2-diol ester(3-MCPDE)were studied in camellia oil.It is important to study the changes in the content of PAHs and 3-MCPDE at different refining stages(from crude oil to the final refined oil product)to elucidate the influence of the refining procedures on their change.Materials and methods:The PAHs and 3-MCPDE in camellia oil from different refining stages(from crude oil to the product)of a plant were analyzed by gas chromatography–mass spectrometry and calculated by the internal standard method.Results:The overall PAH content was(79.64±2.43)μg/kg in crude camellia oil.After refining treatment,the PAH content decreased to(18.75±0.55)μg/kg.The 3-MCPDE content increased during the refining process from 0 mg/kg in the crude oil to 4.62 mg/kg in the refined oil product.Conclusions:This is the first study to simultaneously monitor changes in both PAH and 3-MCPDE contents during the production of camellia oil.These results confirmed the effectiveness of the refining method on PAH removal and the increase in 3-MCPDE at high temperature.It is suggested that novel processing methods or refining parameters need further optimization to decrease the overall concentrations of PAHs and 3-MCPDE in camellia oil.展开更多
基金the financial support from the Science Foundation of China University of Petroleum,Beijing(2462020YXZZ038)
文摘Compared with retail prices of state-owned companies used in almost all existing studies,China’s refined oil wholesale prices of private enterprises and local refineries are more affected by the market and better reflect the real supply-demand situation.For the first time,this paper applies own-monitored dailyfrequency wholesale prices of China’s private enterprises and local refineries during 2013-2020 to derive spillover effects of international crude oil prices on China’s refined oil prices through the VAR-BEKKGARCH(vector autoregression-Baba,Engle,Kraft,and Kroner-generalized autoregressive conditional heteroscedasticity)model,and then tries to forecast wholesale prices through the PCA-BP(principal component analysis-back propagation)neural network model.Results show that international crude oil prices have significant mean spillover and volatility spillover effects on China’s refined oil wholesale prices.Changes in crude oil prices are the Granger cause of changes in refined oil wholesale prices.With the improvement of China’s oil-pricing mechanism in 2016,the volatility spillover from the international crude oil market to China’s refined oil market gradually increases,and the BRENT price variation has an increasing impact on the refined oil wholesale price variation.The PCA-BP model could serve as a candidate tool for forecasting China’s refined oil wholesale prices.
基金supported by the NationalNatural Science Foundation of China(No.31972110)the National Key R&D Program of China(No.2018YFD0401102).
文摘Phytosterols,which are naturally occurring in plants,have excellent nutritional and health values on lowering both the blood cholesterol level and the risk of cardiovascular diseases.Edible oils are the main source of daily intake of phytosterols,whereas the properties of phytosterols may vary a lot depending on their sources.During the processing of edible oil including refining and frying,phytosterol's content fluctuates,which influences the properties of the final product.Phytosterols and their derivatives undergo physical migration between different phases and chemical conversion during the processing,which reduces the quality and the commercial value of edible oils.Therein,the loss of phytosterols is the major concern in the process of neutralization and deodorization.In addition,oxidation and thermal degradation of phytosterols occur simultaneously during frying,which also reduces the content of phytosterols.Nevertheless,the oil matrix has a promoting or an inhibitory effect on the thermal oxidation of phytosterols.Therefore,various efforts have been devoted to analyzing and improving the remaining contents of phytosterols in edible oil.Regardless of the processing method,temperature plays an important role in the loss of phytosterols.At present,themain analysismethods of phytosterols include gas chromatography and liquid chromatography,inwhich the pretreatment of different types of phytosterols is also a crucial step.This review focused on the following topics comprehensively:(i)the distribution of phytosterols in the oil-containing plants and edible oils during the refining processing;(ii)the pretreatment and analysis methods of various phytosterols(free phytosterols,phytosteryl fatty acid esters,phytosteryl glycosides and acylated phytosteryl glycosides);(iii)the variation of phytosterols in process of esterification and oxidation,storage and so on.The study also proposed that the investigation in the loss and safety of phytosterols during processing of the vegetable oils should be proceeded further in combination with efficient and accurate chromatography methods.
文摘The article is the result of theoretical and experimental studies aimed at determining the structural groups of modern bituminous materials in order to assess the raw materials, production technology, rational directions for their use in construction, the road industry and waterproofing. Commercial oil bitumen, raw tars and heavy oil residues (semi-finished products) of oil refineries aimed at meeting large-tonnage needs have been studied. The assessment was carried out according to the group hydrocarbon composition, by liquid chromatography using model compounds. Comparative analysis showed a general trend for all studied samples of petroleum bitumen: low content of asphaltenes (from 3.9 to 23.9 wt.%), low content of resins (from 11 to 19.07 wt%), insufficient for the formation of stable structuring layers, and a significant content of aromatic hydrocarbons, including heavy aromatic compounds (more than 20 wt.%). An assumption was made about the influence of the origin and the structure obtained during the processing of asphaltenes and resins on the transition from one type of bituminous structure to another based on the lyophility of high-molecular group components. A comparative structural characteristic of heavy oil residues from gasoline and oil production is considered in comparison with bitumens of various viscosities. Recommendations are given on the technology of processing petroleum feedstock and the use of heavy oils in order to obtain a given bitumen structure for the production of rational bitumen products for construction and waterproofing.
基金partially supported by the National Natural Science Foundation of China(51874325)Science Foundation of China University of Petroleum,Beijing(2462021BJRC009)。
文摘Accurate sales prediction in filling stations is the basis to fill in the refined oil in time and avoid the outof-stock as much as possible.Considering the defect of great“lag”in the general time series model,this paper summarizes the multiple factors that influence the oil sales and develops a multivariable long short-term memory(LSTM)neural network,with the hyper-parameters being improved by the genetic algorithm(GA).To further improve the prediction accuracy,the proposed LSTM neural network is generalized to bidirectional LSTM(Bi LSTM),in which the impact of future factors on present sales can be taken into account by backward training.Finally,different LSTM structures and genetic algorithm parameters are tested to discuss their impact on prediction accuracy.Results demonstrated that genetic algorithm improved Bi LSTM model is superior to extreme gradient boosting,ARIMA,and artificial neural network,having the highest accuracy of 89%.
基金the“National Key Research and Development Program of China”(Project NO.2016YFD0400202-8).
文摘In this study,the effects of chemical refining on the physicochemical indices,environmental pollutants,lipid functional groups,relaxation characteristics,fatty acid profiles,and triglyceride(TG)molecular species in crude oil extracted from small fish in Mauritania were evaluated.The acid,peroxide,and iodine values of crude oil were identified as 5.52 mg KOH/g,1.73 meq/kg,and 200.78 g/100 g oil,respectively.After refining,these values were determined to be 0.29 mg KOH/g,0.76 meq/kg,and 210.80 g/100 g oil,respectively.The polychlorinated biphenyls and arsenic content of crude oil were identified as 32.30μg/kg and 1.00 mg/kg,respectively.After refining,these were not detected.The content of eicosapentaenoic acid(EPA)and docosahexaenoic acid(DHA)accounted for as much as 87.55%of the polyunsaturated fatty acids in the refined oil,indicating that high-quality fish oil is suitable as a food supplement.The correlation coefficient of the infrared spectra before and after refining was 0.968,and the relaxation time and peak shape data were almost similar before and after purification.Meanwhile,there were no significant differences(P≥0.05)in fatty acid profiles between the crude and refined oils,except for C16:0(P<0.01).Based on UPLC-Q E-MS/MS detection,137 TG molecules were identified in both crude and refined oils.Among the detected TG molecular species,64 contained EPA or DHA,which accounted for 46.83%and 46.00%of the total TG content in crude and refined oils,respectively.After refining,the content of the molecular species decreased by 31.95 mg/10 g,among which the three most variable molecular species were TG(16:0/18:1/22:6),(16:1/16:2/18:1),and(18:4/16:0/20:5),accounting for 29.26%of the decline of the molecular species.Overall,the refining process had little effect on the fatty acid profile and distribution of TG molecular species in fish oil.
基金funded by the Key Research and Development Program of Guangdong Province(No.2019B020212001)Zhejiang Basic Public Welfare Research Project(LGN19C200003)+1 种基金the National Key Research and Development Program of China(2018YFC1603600)National Natural Science Foundation of China(No.31871884).
文摘Objectives:Polycyclic aromatic hydrocarbons(PAHs)and 3-monochloropropane-1,2-diol ester(3-MCPDE)were studied in camellia oil.It is important to study the changes in the content of PAHs and 3-MCPDE at different refining stages(from crude oil to the final refined oil product)to elucidate the influence of the refining procedures on their change.Materials and methods:The PAHs and 3-MCPDE in camellia oil from different refining stages(from crude oil to the product)of a plant were analyzed by gas chromatography–mass spectrometry and calculated by the internal standard method.Results:The overall PAH content was(79.64±2.43)μg/kg in crude camellia oil.After refining treatment,the PAH content decreased to(18.75±0.55)μg/kg.The 3-MCPDE content increased during the refining process from 0 mg/kg in the crude oil to 4.62 mg/kg in the refined oil product.Conclusions:This is the first study to simultaneously monitor changes in both PAH and 3-MCPDE contents during the production of camellia oil.These results confirmed the effectiveness of the refining method on PAH removal and the increase in 3-MCPDE at high temperature.It is suggested that novel processing methods or refining parameters need further optimization to decrease the overall concentrations of PAHs and 3-MCPDE in camellia oil.
