Investigation On Microwave Irradiation-enzyme Coupling Catalysis (MIECC)

Applying microwave irradiation-enzyme coupling catalysis(MIECC) can bring many unique findings, which were quite different from those observed from conventional heating assisted enzymatic reactions. In this paper, the esterification system with caprylic acid and butanol, caprylic acid and glycerol were selected, the solvent effects, regioselectivity in MIECC reaction were studied. The effect of ionic liquid on enzymatic esterification was investigated as well. Additionally, effect of microwave radiation on Maillard reaction was discussed. The main contents and results are as follows:1. The effects of solvent in MIECC reaction were invested through enzymatic esterification between caprylic acid and butanol. When chose n-octane as solvent, with the increasing of substrate concentration, the initial reaction rates increased and then decreased under both conventional heating and microwave irradiation. The microwave irradiation increased the initial reaction rates, and the higher microwave effects appeared in lower substrate concentration. The initial reaction rates altered with the alkanes or arenes carbon number under both heating modes. The effects of isomers solvent with the same logP on reaction rates were different. The effects of MIECC caused by different solvents were different. Under two heating modes, the initial reaction rates did not increased with the increasing of solvent,s logP, but there was an optimum range. When using different solvatochromic parameter token the solvent,s polarity, the relationship between initial reaction rate and solvent polarity was different. The change of fluorescence spectrum of LRI with different treating methods was investigated. The results shown that microwave irradiation couldn,t change the maximum wavelength of fluorescence, but changed the intensity.2. The esterification system with caprylic acid and glycerol was selected for investigating the effect of heating modes on the regionselectivity under different reaction conditions. 1,3-specificity of Novozyme 435 varied with conversion of caprylic acid, water dosage, ratio of substrates and solvents. The contents of 2-monoglyceride and 1,2-diglyceride in the microwaved reaction mixture were higher than that in the conventional heated reaction mixture. In all means microwave irradiation weaken the 1,3-specificity depending on the reaction conditions.3. The effects of ionic liquid ([bmim]PF6) on enzymatic reaction rate and regioselectivity of esterification initial were studied through reaction system of caprylic acid and glycerol. It was found that the initial reaction rates and the conversion of caprylic acid were declined, but 1,3-specificity of Novozyme 435 were strengthened.4. A method of examining acrylamide in cooked popcorn by solid phase extraction/gas chromatography (SPE/GC) was established. The detection limit and the quantification limit were estimated at 3μg/L and 10μg/L, respectively; and the linear correlation coefficient was 0.9938. Seven commercial popcorn samples with different flavors were collected and tested in this paper. The RSD of acrylamide level of caramel sweet popcorn microwaved was 1.95%(n = 6). It was obvious that the high content of reduced sugar leads to high acrylamide content in both heated manners, and the low temperature and quick heating character of microwave leads lower content of acrylamide in microwaved popcorn.