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Comparison of estimation capabilities of response surface methodology (RSM) with artificial neural network (ANN) in lipase-catalyzed synthesis of palm-based wax ester.

Basri M, Rahman RN, Ebrahimpour A, Salleh AB, Gunawan ER, Rahman MB - BMC Biotechnol. (2007)

Bottom Line: The actual experimental percentage yield was 84.6% at optimum condition, which compared well to the maximum predicted value by ANN (83.9%) and RSM (85.4%).The order of effective parameters on wax ester percentage yield were; respectively, time with 33.69%, temperature with 30.68%, amount of enzyme with 18.78% and substrate molar ratio with 16.85%, whereas R2 and AAD were determined as 0.99998696 and 1.377 for ANN, and 0.99991515 and 3.131 for RSM respectively.Though both models provided good quality predictions in this study, yet the ANN showed a clear superiority over RSM for both data fitting and estimation capabilities.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia. mahiran@science.upm.edu.my

ABSTRACT

Background: Wax esters are important ingredients in cosmetics, pharmaceuticals, lubricants and other chemical industries due to their excellent wetting property. Since the naturally occurring wax esters are expensive and scarce, these esters can be produced by enzymatic alcoholysis of vegetable oils. In an enzymatic reaction, study on modeling and optimization of the reaction system to increase the efficiency of the process is very important. The classical method of optimization involves varying one parameter at a time that ignores the combined interactions between physicochemical parameters. RSM is one of the most popular techniques used for optimization of chemical and biochemical processes and ANNs are powerful and flexible tools that are well suited to modeling biochemical processes.

Results: The coefficient of determination (R2) and absolute average deviation (AAD) values between the actual and estimated responses were determined as 1 and 0.002844 for ANN training set, 0.994122 and 1.289405 for ANN test set, and 0.999619 and 0.0256 for RSM training set respectively. The predicted optimum condition was: reaction time 7.38 h, temperature 53.9 degrees C, amount of enzyme 0.149 g, and substrate molar ratio 1:3.41. The actual experimental percentage yield was 84.6% at optimum condition, which compared well to the maximum predicted value by ANN (83.9%) and RSM (85.4%). The order of effective parameters on wax ester percentage yield were; respectively, time with 33.69%, temperature with 30.68%, amount of enzyme with 18.78% and substrate molar ratio with 16.85%, whereas R2 and AAD were determined as 0.99998696 and 1.377 for ANN, and 0.99991515 and 3.131 for RSM respectively.

Conclusion: Though both models provided good quality predictions in this study, yet the ANN showed a clear superiority over RSM for both data fitting and estimation capabilities.

Show MeSH
Three dimensional plot showing the effect of amount of enzyme, incubation time and their mutual effect on the synthesis of wax esters. Other variables are constant: molar ratio palm oil:oleyl alcohol, 1:3 and temperature, 50°C.
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Figure 7: Three dimensional plot showing the effect of amount of enzyme, incubation time and their mutual effect on the synthesis of wax esters. Other variables are constant: molar ratio palm oil:oleyl alcohol, 1:3 and temperature, 50°C.

Mentions: Figure 6 and Figure 7 depict the response surface plots as function of incubation time versus substrate molar ratio (palm oil:oleyl alcohol) and incubation time versus amount of enzyme, at temperature 55°C. A reaction with moderate substrate molar ratio 1:3 (palm oil:oleyl alcohol) and highest reaction time favored maximal yield and decreases up to substrate molar ratio 1:3.5. This may be due to at around critical molar ratio, the competing alcohol binding reduces the formation of the acyl-enzyme complex and thereby result in decrease in alcoholysis [26]. Kiran et al. reported that an enzymatic-catalyzed synthesis of lauroyl lactic acid had shown that the interaction of incubation time versus lactic acid concentration had a positive effect [28]. A linear increase in wax esters production with increase in amount of enzyme and incubation time was observed. The rate increased proportionally with enzyme loading. Similar trends for interaction of enzyme concentration and incubation time was reported by Hamsaveni et al. in their lipozyme-catalyzed esterification of isobutyric acid with isobutyl alcohol [7].


Comparison of estimation capabilities of response surface methodology (RSM) with artificial neural network (ANN) in lipase-catalyzed synthesis of palm-based wax ester.

Basri M, Rahman RN, Ebrahimpour A, Salleh AB, Gunawan ER, Rahman MB - BMC Biotechnol. (2007)

Three dimensional plot showing the effect of amount of enzyme, incubation time and their mutual effect on the synthesis of wax esters. Other variables are constant: molar ratio palm oil:oleyl alcohol, 1:3 and temperature, 50°C.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2211475&req=5

Figure 7: Three dimensional plot showing the effect of amount of enzyme, incubation time and their mutual effect on the synthesis of wax esters. Other variables are constant: molar ratio palm oil:oleyl alcohol, 1:3 and temperature, 50°C.
Mentions: Figure 6 and Figure 7 depict the response surface plots as function of incubation time versus substrate molar ratio (palm oil:oleyl alcohol) and incubation time versus amount of enzyme, at temperature 55°C. A reaction with moderate substrate molar ratio 1:3 (palm oil:oleyl alcohol) and highest reaction time favored maximal yield and decreases up to substrate molar ratio 1:3.5. This may be due to at around critical molar ratio, the competing alcohol binding reduces the formation of the acyl-enzyme complex and thereby result in decrease in alcoholysis [26]. Kiran et al. reported that an enzymatic-catalyzed synthesis of lauroyl lactic acid had shown that the interaction of incubation time versus lactic acid concentration had a positive effect [28]. A linear increase in wax esters production with increase in amount of enzyme and incubation time was observed. The rate increased proportionally with enzyme loading. Similar trends for interaction of enzyme concentration and incubation time was reported by Hamsaveni et al. in their lipozyme-catalyzed esterification of isobutyric acid with isobutyl alcohol [7].

Bottom Line: The actual experimental percentage yield was 84.6% at optimum condition, which compared well to the maximum predicted value by ANN (83.9%) and RSM (85.4%).The order of effective parameters on wax ester percentage yield were; respectively, time with 33.69%, temperature with 30.68%, amount of enzyme with 18.78% and substrate molar ratio with 16.85%, whereas R2 and AAD were determined as 0.99998696 and 1.377 for ANN, and 0.99991515 and 3.131 for RSM respectively.Though both models provided good quality predictions in this study, yet the ANN showed a clear superiority over RSM for both data fitting and estimation capabilities.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia. mahiran@science.upm.edu.my

ABSTRACT

Background: Wax esters are important ingredients in cosmetics, pharmaceuticals, lubricants and other chemical industries due to their excellent wetting property. Since the naturally occurring wax esters are expensive and scarce, these esters can be produced by enzymatic alcoholysis of vegetable oils. In an enzymatic reaction, study on modeling and optimization of the reaction system to increase the efficiency of the process is very important. The classical method of optimization involves varying one parameter at a time that ignores the combined interactions between physicochemical parameters. RSM is one of the most popular techniques used for optimization of chemical and biochemical processes and ANNs are powerful and flexible tools that are well suited to modeling biochemical processes.

Results: The coefficient of determination (R2) and absolute average deviation (AAD) values between the actual and estimated responses were determined as 1 and 0.002844 for ANN training set, 0.994122 and 1.289405 for ANN test set, and 0.999619 and 0.0256 for RSM training set respectively. The predicted optimum condition was: reaction time 7.38 h, temperature 53.9 degrees C, amount of enzyme 0.149 g, and substrate molar ratio 1:3.41. The actual experimental percentage yield was 84.6% at optimum condition, which compared well to the maximum predicted value by ANN (83.9%) and RSM (85.4%). The order of effective parameters on wax ester percentage yield were; respectively, time with 33.69%, temperature with 30.68%, amount of enzyme with 18.78% and substrate molar ratio with 16.85%, whereas R2 and AAD were determined as 0.99998696 and 1.377 for ANN, and 0.99991515 and 3.131 for RSM respectively.

Conclusion: Though both models provided good quality predictions in this study, yet the ANN showed a clear superiority over RSM for both data fitting and estimation capabilities.

Show MeSH