Optimization of lipase-catalyzed synthesis of diglycerol monooleate by response surface methodology Noureddin El-Boulifi, Jose Aracil, Mercedes Martı´nez* Chemical Engineering Department, Chemistry Faculty, Complutense University, 28040 Madrid, Spain article info Article history: Received 23 May 2013 Received in revised form 10 December 2013 Accepted 15 December 2013 Available online 17 January 2014 Keywords: Diglycerol Diglycerol monooleate Novozym 435 Response surface methodology Surfactant abstract The optimization of the lipase-catalyzed esterification of pure diglycerol (3-(2,3- dihydroxypropoxy)propane-1,2-diol) with pure oleic acid to produce pure diglycerol mon- ooleate (E475) which is a non-ionic surfactants, was performed. Six immobilized lipases were tested and the best oleic acid conversion was attained with Novozym 435 from Candida antarctica which was selected to optimize the reaction conditions by response surface methodology (RSM). Well-fitting quadratic polynomial regression model for acid conversion was established with regard to temperature (65 Ce75 C) and catalyst con- centration (mass fraction of 1e5%). The two factors investigated positively affected acid conversion, with catalyst concentration having the greatest effect. The regression equation obtained by central composite design of RSM predicted optimal reaction conditions of 77 C and 5.8%. Under these optimal conditions the model obtained in this work has been tested in scale-up experiment, and the resulting acid conversion was 93.9% with an accuracy of 97.4%. Within the experimental range studied the results model give good agreement with the experimental data. ª 2013 Elsevier Ltd. All rights reserved. 1. Introduction Polyglycerol esters of fatty acids (PGE, E475) are non-ionic surfactants that have been used during the last years as emulsifiers in food and personal care products [1,2]. More recently, new industrial applications based on PGE have been developed, includes their utilization as antifogging and anti- static additives, lubricants and plasticizers [1,3]. The PGE are an amphipathic molecules with hydrophilic moiety (hy- droxyl groups) attached to a hydrophobic backbone (alkyl chain). These two parts provide a compound with interfacial activity and give rise to a wide range of surface chemistry functions. Glycerol is the main by-product of biodiesel production. As the biodiesel production is increasing exponentially, the crude glycerol generated from the transesterification of oils has also been generated in a large quantity. The valorization of glycerol as by-product increases the economic sustainability of the biodiesel industry. Within this context, among the wide application of glycerol in food, the use of glycerol for the production of non-ionic surfactants like glycerol esters of fatty acids, can be a good way forward to development of surfac- tants products entirely derived from renewable resource [4,5]. However, glycerol itself is not a good primary constituent of the hydrophilic part of the surfactant and polyglycerols are needed to increase the hydrophilicity and to adjust the hydrophilic-hydrophobic balance of the products. Since the * Corresponding author. Tel./fax: þ34 91 394 4167. E-mail address: [email protected](M.Martı´nez). Available online at www.sciencedirect.com ScienceDirect http://www.elsevier.com/locate/biombioe biomass and bioenergy 61 (2014) 179 e186 0961-9534/$ e see front matter ª 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.biombioe.2013.12.009
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b i om a s s a n d b i o e n e r g y 6 1 ( 2 0 1 4 ) 1 7 9e1 8 6
Available online at w
ScienceDirect
http: / /www.elsevier .com/locate/biombioe
Optimization of lipase-catalyzed synthesis ofdiglycerol monooleate by response surfacemethodology
Noureddin El-Boulifi, Jose Aracil, Mercedes Martınez*
Chemical Engineering Department, Chemistry Faculty, Complutense University, 28040 Madrid, Spain
b i om a s s a n d b i o e n e r g y 6 1 ( 2 0 1 4 ) 1 7 9e1 8 6 185
positively affected the levels of acid conversion, with catalyst
concentration having the greatest effect. In this case, the two
effects have p-values less than 0.05, indicating that they are
significantly different from zero at the 95% confidence level.
Whereas quadratic terms of catalyst concentration and tem-
perature and their interaction had not significant effect
(p > 0.05) on the acid conversion. These results are in agree-
ment with the results shown in the prediction plots for the
acid conversion level by the effect of individual reaction pa-
rameters obtained by our research group in a previous work
[16].
3.4. Optimum conditions and model validation
According to the model, the optimal conditions are likely to
provide the best process response, leading to the highest acid
conversion and process efficiency. Using RSM the two reaction
parameters, temperature and catalyst concentration should
be kept at the highest level (77 �C) and (5.8%), respectively,
within their given ranges to obtain the highest acid
conversion.
To examine the adequacy of the model established, an
experiment at the predicted optimal conditions was carried
out, together with five additional experimental sets selected
from the given ranges of reaction parameters (Table 6). The
regression model was also verified with an experiment at the
predicted optimal conditions, using a 5� 10-3 m3 batch reactor
for the scale up of the process (Table 6). Using this reactor, the
acid conversion reached 93.9%, with an accuracy of 97.4%; the
result was close to that obtained on the smaller scale. There
was considerable agreement between the experimental and
the predicted acid conversion values and this confirmed that
the quadratic model was suitable to predict the course of this
reaction.
4. Conclusion
Novozym 435 was the most effective biocatalyst for the
esterification of pure diglycerol with oleic acid to produce pure
diglycerol monooleate ester, among six commercially avail-
able lipases tested in the present study. The modeling and
optimization of Novozym 435-catalyzed synthesis of
diglycerol monooleate ester was successfully performed by
central composite design and response surface methodology.
The influence of twomain reaction parameters were elucidate
within the experimental range considered and optimal reac-
tion condition were obtained using the established model.
Under these optimal conditions the acid conversion was
93.9%. The coefficient of correlation r (0.985) and analysis of
variance implied that themodel satisfactorily represented the
real relationship of the main reaction parameters and the
response, and have been found to be valid for the scale up the
process.
Acknowledgments
The authors gratefully acknowledge financial support of this
work by the PRI-PIBAR-2011-1375 and “Ministerio de Economıa
y Competitividad” (CTQ-2009-09-088).
r e f e r e n c e s
[1] Benvegnu T, Plusquellec D, Lemiegre L. Surfactants fromrenewable sources: synthesis and applications. In: Naceur M,Gandini A, editors. Monomers, polymers and compositesfrom renewable sources. Amsterdam: Elsevier Limited; 2008.pp. 153e78.
[2] Zhu Q, Li T, Wang Y, Yang B, Ma Y. A two-stage enzymaticprocess for synthesis of extremely pure high oleic glycerolmonooleate. Enzym Microb Tech 2010;48(2):143e7.
[3] Sakamoto M, Ohba A, Kuriyama J, Maruo K, Ueno S, Sato K.Influences of fatty acid moiety and esterification ofpolyglycerol fatty acid esters on the crystallization of palmmid fraction in oil-in-water emulsion. Colloids Surf B2004;37(1e2):27e33.
[4] Kjellin M, Johansson I. Surfactants from renewableresources. 1st ed. Chichester: John Wiley & Sons Inc; 2010.
[5] Sanchez N, Martinez M, Aracil J. Selective esterification ofglycerine to 1-glycerol monooleate. 2. Optimization studies.Ind Eng Chem Res 1997;36(5):1529e32.
[6] Pitzalis P, Monduzzi M, Krog N, Larsson H, Ljusberg-Wahren H, Nylander T. Characterization of the liquid-crystalline phases in the glycerol monooleate/diglycerolmonooleate/water system. Langmuir 2000;16(15):6358e65.
[7] Kato T, Nakamura T, Yamashita M, Kawaguchi M, Kato T,Itoh T. Surfactant properties of purified polyglycerolmonolaurates. J Surfactants Deterg 2003;6(4):331e7.
[8] Alvarez JM, Rodrıguez JM. Interfacial properties of diglycerolesters and caseinate mixed films at the air-water interface.J Phys Chem C 2007;111(12):4790e9.
[9] Nakamura T, Yamashita M, inventors; Taiyo Kagaku Co.,Ltd., assignee. Polyether-polyol compound. United Statespatent US 20020035238; 2002 Mar 21.
[10] Marquez-Alvarez C, Sastre E, Perez-Pariente J. Solid catalystsfor the synthesis of fatty esters of glycerol, polyglycerols andsorbitol from renewable resources. Top Catal2004;27(1e4):105e17.
b i om a s s a n d b i o e n e r g y 6 1 ( 2 0 1 4 ) 1 7 9e1 8 6186
[13] Corma A, Iborra S, Velty A. Chemical routes for thetransformation of biomass into chemicals. Chem Rev2007;107(6):2411e502.
[14] Treichel H, Oliveira D, Mazutti MA, Di Luccio M, Oliveira JV. Areview on microbial lipases production. Food BioprocessTech 2010;3(2):182e96.
[15] Aehle W. Enzymes in industry: production and applications.3th ed. Weinheim: Wiley-VCH; 2007.
[16] Martinez M, Oliveros R, Aracil J. Synthesis of biosurfactants:enzymatic esterification of diglycerol and oleic acid. 1.Kinetic modelling. Ind Eng Chem Res 2011;50(11):6609e14.
[17] Pollard D, Kosjek B. Industrial-scale applications of enzymesin non-aqueous solvents. In: Carrea G, Riva S, editors.
Organic synthesis with enzymes in non-aqueous media.Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA; 2008.pp. 169e88.
[18] El-Boulifi N, Aracil J, Martınez M. Lipase-catalyzed synthesisof isosorbide monoricinoleate: process optimization byresponse surface methodology. Bioresour Technol2010;101(22):8520e5.
[19] Barros Neto B, Scarminio IS, Bruns RE. Como FazerExperimentos: Pesquisa e desenvolvimento na ciencia e naindustria. 2nd ed. Campinas: Unicamp; 2003.
[20] Joglekar AM, May AT. Product excellence through design ofexperiments. Cereal Foods World 1987;32(12):857e68.