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The Journal of Supercritical Fluids
journal homepage: www.elsevier.com/locate/supflu
Optimization of enzymatic synthesis of cocoa butter analog from camel hump fat in supercritical carbon dioxide by response surface method (RSM)
Hajar Shekarchizadeh a , Mahdi Kadivar a,∗ , Hasan S. Ghaziaskar a ,Marzieh Rezayat b
Department of Food Science and Technology, Isfahan University of Technology, Isfahan 84156, Iran Department of Chemistry, Isfahan University of Technology, Isfahan 84156, Iran
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Supercritical carbon dioxide (SC-CO2 ) has been studied as a medium for esteriﬁcation of camel hump fat and tristearin in producing cocoa butter analogusing Immobilized Thermomyces lanuginosus lipase (Lipozyme TL IM) as a biocatalyst. Process conditions (pressure, temperature, tristearin/camel hump fat ratio, water content, and incubation time) were optimized by conducting experiments at ﬁve different levels using the response surface method (RSM). A second-order polynomial response surface equation was developed indicating the effect ofvariables on cocoa butter analog yield. Contour maps generated using the response surface equation showed that all the experimental variables signiﬁcantly affected the yield. The pressure, 10 MPa; temperature, 40 ◦ C; SSS/CHF ratio, 1:1; water content, 10% (w/w); and incubation time, 3 h were found to be the optimum conditions to achieve the maximum yield of cocoa butter analog. © 2009 Elsevier B.V. Allrights reserved.
Article history: Received 2 January 2009 Received in revised form 6 March 2009 Accepted 13 March 2009 Keywords: Enzymatic interesteriﬁcation Camel hump fat Lipozyme TL IM Supercritical carbon dioxide (SC-CO2 ) RSM
1. Introduction Fat constitutes one-third of the chocolate content and its properties affect certain parameters of the chocolate manufacturing process, especiallyat the tempering and cooling stages . Melting fast and completely in mouth while hard and brittle at room temperature, cocoa butter is the fat phase in chocolate and is characterized by sharp melting point, desirable physicochemical properties, and fatty acid components . It is composed predominantly (>70%) of symmetrical triacylglycerols, 1,3-dipalmitoyl2-oleoylglycerol (POP),1(3)-palmitoyl-3(1)-stearoyl-2-monoolein (POS), and 1,3-distearoyl-2-oleoylglycerol (SOS), with oleic acid in the sn-2 position . The typical fatty acid composition of cocoa butter in mole percentage is: C16:0 24.4%, C18:0 33.6%, C18:1 37.0%, C18:2 3.4%, and others 1.6%. Cocoa butter melts at temperatures between 32 and 35 ◦ C and is able to re-crystallize during processing to a stable crystal mode .World production of cocoa butter was about 675,000 metric tons in 2001. Numerous factors, however, including the degree of uncertainty in supply, variability in quality, and price premium compared to other fats have driven the search for alternatives . Cocoa butter replacers (CBRs) are those fats which replace cocoa butter partially or wholly in chocolate products. CBRs are further classiﬁed as (i)cocoa-butter-equivalents (CBE), which behave like cocoa butter and are able to blend in cocoa butter in any proportion without altering the physicochemi-
∗ Corresponding author. Tel.: +98 311 3913382; fax: +98 311 3912254. E-mail address: firstname.lastname@example.org (M. Kadivar). 0896-8446/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.supﬂu.2009.03.005
calcharacteristics of cocoa butter; and (ii) cocoa-butter-substitute (CBS), which are fats that can be blended with cocoa butter to a limited extent, without signiﬁcantly altering its physicochemical characteristics . Procedures of chemical interesteriﬁcation for analogs have been developed for years from cheap fats and oils and are found to be practical to industries . Recently, preparation of CBE...