Monoacylglycerols(MAGs) and diacylglycerols(DAGs) are partial glycerides widely used in food industry. They are safe and non-toxic food emulsifiers, especially for MAGs. MAGs account for approximately 75% of the total...Monoacylglycerols(MAGs) and diacylglycerols(DAGs) are partial glycerides widely used in food industry. They are safe and non-toxic food emulsifiers, especially for MAGs. MAGs account for approximately 75% of the total emulsifiers in food industry worldwide. DAGs are recognized as functional cooking oils, they can suppress body fat accumulation and postprandial serum triacylglycerols(TAGs) level. The traditional production of MAGs and DAGs is based on the chemical method, which requires high reaction temperature usually up to 200–260 ℃. Such high temperature is not suitable for oil containing heat sensitive polyunsaturated fatty acids. Enzymatic approach has been received increasing attentions. Enzymatic production of partial glycerides to replace chemical processes has been in industry, particularly for DAGs production as the products have been claimed as a functional and nutritional oil. Enzyme technology for the processing of oils and fats has been moved to industry step by step and case by case during the last 20 years. More and more applications are particularly moving into bulky oils and fats processing. At the same time, the cost of enzymes as a commercial product is reducing steadily. This review summarized the recent 15 years advances on the the enzymatic preparation of MAGs and DAGs. The critical process parameters under different reaction routes were presented and emphasized. The reaction media not only increased the homogeneity of the reaction system, but also shifted the reaction equilibrium towards the target product generation, and this part was stated in detail. In addition, the patent evaluation was included, and the application of MAGs and DAGs was covered.展开更多
The production of polyunsaturated fatty acids （PUFAs） concentrates by enzymatic catalysis has gained interest due to their stereospecificity and the milder conditions employed compared to the use of inorganic cataly...The production of polyunsaturated fatty acids （PUFAs） concentrates by enzymatic catalysis has gained interest due to their stereospecificity and the milder conditions employed compared to the use of inorganic catalysts. The enzymatic glycerolysis of sardine oil by Lipozymeò435 to get PUFA concentrates in the forms of di‐and monoacylglycerols （DAGs, MAGs） in an optimized amount of tert‐butanol as the organic solvent was studied. First, mass transfer limitation of the reaction sys‐tem was analyzed. The effects of different operating variables such as lipase loading, temperature and feed composition were investigated. A semi‐empirical kinetic model based on the reversible elementary reactions of glycerolysis and hydrolysis of the glycerides was employed to correlate the experimental kinetic data. A molar ratio glycerol：oil of 3：1 was the optimum, which produced more than 84 wt%of MAG at 323 K. A comparison with other glycerolysis systems was performed using MAG yield, reaction rate and significance of kinetic parameters.展开更多
Potassium and cesium salts of tungstophosphoric acid were prepared by precipitation method. For sake of comparison HPW, potassium and cesium tungstophosphates were supported on silica (20 wt%) by wet impregnation meth...Potassium and cesium salts of tungstophosphoric acid were prepared by precipitation method. For sake of comparison HPW, potassium and cesium tungstophosphates were supported on silica (20 wt%) by wet impregnation method. The catalysts were characterized by XRD, nitrogen adsorption-desorption measurements at 77 K, and the catalytic activity has been studied by using the catalytic conversion of tert-butanol at temperatures between 323 and 423 K. The results revealed that all of the catalysts were active and selective towards dehydration of tert-butanol yielding isobutene with low amount of isooctene as result of oligomerization process. Substitution of one proton of HPW by cesium or potassium cation exerted no measurable effect on the catalytic activity. The conversion over unsupported catalysts increased by increasing the cation content per Keggin unit of x ≥ 2. Supporting the previous salts on SiO2 resulted in a significant decrease in the catalytic activity upon increasing cation content. Activation energy was calculated for different solids.展开更多
High capacity Fe_(3)O_(4)-based anode materials have attracted a great deal of attention as an alternative to commercial graphite in Li-ion batteries(LIBs).However,it is still a challenge to alleviate the fast capacit...High capacity Fe_(3)O_(4)-based anode materials have attracted a great deal of attention as an alternative to commercial graphite in Li-ion batteries(LIBs).However,it is still a challenge to alleviate the fast capacity fading of Fe_(3)O_(4) due to the intercalation of Lit.In this work,we develop a novel and effective strategy to rapidly fabricate the hollow Fe_(3)O_(4) nanostructures via the solvent-induced effect.The influence of the ratio of the tert-butanol(TB)and the water on the microstructure was further discussed.As expected,when the hollow nanostructures based on the 1:1 ratio of TB and water is used as the anode material for LIBs,a high reversible capacity of 1020 mA h g^(-1) after 100 cycles at 1 A g^(-1) and 450 mA h g^(-1) even for 5 A g^(-1) after 1000 cycles can be obtained,paving a new avenue to fabricate the functionally hollow nanostructures for high-performance anode materials or other applications.展开更多
基金supported by the National Natural Science Foundation of China(31772000).
文摘Monoacylglycerols(MAGs) and diacylglycerols(DAGs) are partial glycerides widely used in food industry. They are safe and non-toxic food emulsifiers, especially for MAGs. MAGs account for approximately 75% of the total emulsifiers in food industry worldwide. DAGs are recognized as functional cooking oils, they can suppress body fat accumulation and postprandial serum triacylglycerols(TAGs) level. The traditional production of MAGs and DAGs is based on the chemical method, which requires high reaction temperature usually up to 200–260 ℃. Such high temperature is not suitable for oil containing heat sensitive polyunsaturated fatty acids. Enzymatic approach has been received increasing attentions. Enzymatic production of partial glycerides to replace chemical processes has been in industry, particularly for DAGs production as the products have been claimed as a functional and nutritional oil. Enzyme technology for the processing of oils and fats has been moved to industry step by step and case by case during the last 20 years. More and more applications are particularly moving into bulky oils and fats processing. At the same time, the cost of enzymes as a commercial product is reducing steadily. This review summarized the recent 15 years advances on the the enzymatic preparation of MAGs and DAGs. The critical process parameters under different reaction routes were presented and emphasized. The reaction media not only increased the homogeneity of the reaction system, but also shifted the reaction equilibrium towards the target product generation, and this part was stated in detail. In addition, the patent evaluation was included, and the application of MAGs and DAGs was covered.
基金the Spanish Government through MINECO (CTQ2012-39131-C02-01) for financial supportUniversity of Burgos for a pre-doctoral fellowshipMINECO for a pre-doctoral grant (reference BES-2013-063937)
文摘The production of polyunsaturated fatty acids （PUFAs） concentrates by enzymatic catalysis has gained interest due to their stereospecificity and the milder conditions employed compared to the use of inorganic catalysts. The enzymatic glycerolysis of sardine oil by Lipozymeò435 to get PUFA concentrates in the forms of di‐and monoacylglycerols （DAGs, MAGs） in an optimized amount of tert‐butanol as the organic solvent was studied. First, mass transfer limitation of the reaction sys‐tem was analyzed. The effects of different operating variables such as lipase loading, temperature and feed composition were investigated. A semi‐empirical kinetic model based on the reversible elementary reactions of glycerolysis and hydrolysis of the glycerides was employed to correlate the experimental kinetic data. A molar ratio glycerol：oil of 3：1 was the optimum, which produced more than 84 wt%of MAG at 323 K. A comparison with other glycerolysis systems was performed using MAG yield, reaction rate and significance of kinetic parameters.
文摘Potassium and cesium salts of tungstophosphoric acid were prepared by precipitation method. For sake of comparison HPW, potassium and cesium tungstophosphates were supported on silica (20 wt%) by wet impregnation method. The catalysts were characterized by XRD, nitrogen adsorption-desorption measurements at 77 K, and the catalytic activity has been studied by using the catalytic conversion of tert-butanol at temperatures between 323 and 423 K. The results revealed that all of the catalysts were active and selective towards dehydration of tert-butanol yielding isobutene with low amount of isooctene as result of oligomerization process. Substitution of one proton of HPW by cesium or potassium cation exerted no measurable effect on the catalytic activity. The conversion over unsupported catalysts increased by increasing the cation content per Keggin unit of x ≥ 2. Supporting the previous salts on SiO2 resulted in a significant decrease in the catalytic activity upon increasing cation content. Activation energy was calculated for different solids.
基金financially supported by the National Natural Science Foundation of China(Grant no.51673154,51173139,51503159).
文摘High capacity Fe_(3)O_(4)-based anode materials have attracted a great deal of attention as an alternative to commercial graphite in Li-ion batteries(LIBs).However,it is still a challenge to alleviate the fast capacity fading of Fe_(3)O_(4) due to the intercalation of Lit.In this work,we develop a novel and effective strategy to rapidly fabricate the hollow Fe_(3)O_(4) nanostructures via the solvent-induced effect.The influence of the ratio of the tert-butanol(TB)and the water on the microstructure was further discussed.As expected,when the hollow nanostructures based on the 1:1 ratio of TB and water is used as the anode material for LIBs,a high reversible capacity of 1020 mA h g^(-1) after 100 cycles at 1 A g^(-1) and 450 mA h g^(-1) even for 5 A g^(-1) after 1000 cycles can be obtained,paving a new avenue to fabricate the functionally hollow nanostructures for high-performance anode materials or other applications.
