Hen-Yi Ju

Continuous Production of Lipase-Catalyzed Biodiesel in a Packed-Bed Reactor: Optimization and Enzyme Reuse Study

An optimal continuous production of biodiesel by methanolysis of soybean oil in a packed-bed reactor was developed using immobilized lipase (Novozym 435) as a catalyst in a tert-butanol solvent system. Response surface methodology (RSM) and Box-Behnken design were employed to evaluate the effects of reaction temperature, flow rate, and substrate molar ratio on the molar conversion of biodiesel. The results showed that flow rate and temperature have significant effects on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions were as follows: flow rate 0.1 mL/min, temperature 52.1°C, and substrate molar ratio 1 : 4. The predicted and experimental values of molar conversion were 83.31 ± 2.07% and 82.81 ± .98%, respectively. Furthermore, the continuous process over 30 days showed no appreciable decrease in the molar conversion. The paper demonstrates the applicability of using immobilized lipase and a packed-bed reactor for continuous biodiesel synthesis.

Optimized enzymatic synthesis of caffeic acid phenethyl ester by RSM.

In this study, optimization of enzymatic synthesis of caffeic acid phenethyl ester (CAPE), catalyzed by immobilized lipase (Novozym 435) from Candida antarctica was investigated. Novozym 435 was used to catalyze caffeic acid and 2-phenylethanol in an isooctane system. Response surface methodology (RSM) and 5-level-4-factor central-composite rotatable design (CCRD) were employed to evaluate the effects of synthesis parameters, such as reaction temperature (30-70 degrees C), reaction time (24-72 hours), substrate molar ratio of caffeic acid to 2-phenylethanol (1:10-1:90) and enzyme amounts (100-500 PLU) on percentage conversion of CAPE by direct esterification. Reaction temperature and time had significant effects on percent conversion. On the basis of ridge max analysis, the optimum conditions for synthesis were: reaction time 59 hours, reaction temperature 69 degrees C, substrate molar ratio 1:72 and enzyme amount 351 PLU. The molar conversion of predicted values and actual experimental values were 91.86+/-5.35% and 91.65+/-0.66%, respectively.

Enzymatic synthesis of rose aromatic ester (2-phenylethyl acetate) by lipase.

BACKGROUND 2-Phenylethyl acetate (2-PEAc) is a highly valued natural volatile ester with a rose-like odour that is widely used to add scent or flavour to cosmetics, soaps, foods and drinks. In this study, 2-PEAc was synthesised enzymatically by transesterification of vinyl acetate with 2-phenethyl alcohol catalysed by immobilised lipase (Novozym(®) 435) from Candida antarctic RESULTS Response surface methodology and a three-level/three-factor Box-Behnken design were used to evaluate the effects of time, temperature and enzyme amount on the molar conversion % of 2-PEAc. The results showed that temperature was the most important variable. Based on the ridge max analysis results, optimum enzymatic synthesis conditions were predicted as a reaction time of 79 min, a temperature of 57.8 °C and an enzyme amount of 122.5 mg. The predicted and experimental yields were 86.4 and 85.4% respectively. CONCLUSION Three immobilised lipases were screened and 15 reaction conditions were tested in order to find the combination for maximum yield. The optimisation of 2-PEAc synthesis catalysed by Novozym(®) 435 was successfully developed. The kinetic study of this transesterification reaction showed that it followed an ordered ping-pong bi-bi mechanism without any inhibition by reactants.

Optimal α-Chymotrypsin-Catalyzed Synthesis of N-Ac-Phe-Gly-NH2

N-Acetyl-phenylalanine-glycinamide (N-Ac-Phe-Gly-NH(2)), a type of dipeptide derivative, was synthesized from N-acetyl phenylalanine ethyl ester and glycinamide and catalyzed by alpha-chymotrypsin, a protease, in a biphasic system. Response surface methodology with a four-factor, five-level central composite rotatable design was employed to evaluate the effects of selected parameters that included incubation time, reaction temperature, enzyme activity, and pH level on the yield of the dipeptide derivative. The results indicated that pH significantly affected the yield of N-Ac-Phe-Gly-NH(2). In a ridge max analysis, the optimum condition for this synthesis included an incubation time of 30.9 min, a reaction temperature of 35.8 degrees C, an enzyme activity of 159.2 U, and a pH of 8.98. The predicted and the actual (experimental) yields were 98.0 and 95.1%, respectively.

Optimization of ultrasound‐accelerated synthesis of enzymatic octyl hydroxyphenylpropionate by response surface methodology

The ultrasound‐accelerated enzymatic synthesis of octyl hydroxyphenylpropionate (OHPP) from p‐hydroxyphenylpropionic acid (HPPA) and octanol was investigated in this study. A commercially available immobilized lipase from Candida antarctica, Novozym® 435, was used as the biocatalyst. A three‐level‐three‐factor Box‐Behnken design experiment and response surface methodology were used to evaluate the effects of temperature, reaction time, and enzyme activity on percent yield of OHPP. The results indicated that temperature and enzyme activity significantly affected percent yield, whereas reaction time did not. A model for the synthesis of OHPP was established. Based on a ridge max analysis, the optimum conditions for OHPP synthesis were predicted to use a reaction temperature of 58.8°C, a reaction time of 14.6 h, and an enzyme activity of 410.5 PLU with a yield of 98.5%. A reaction was performed under these optimal conditions, and a yield of 97.5% ± 0.1% was obtained.