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Revista Lasallista de Investigación

Print version ISSN 1794-4449

Abstract

ALZATE CEBALLOS, J. A; LOPEZ-PADILLA, A; CAICEDO, J. A  and  CANO SALAZAR, J. A. Obtaining the cyclodextrin-curcumin complex and its use as a substitute of tartrazine. Rev. Lasallista Investig. [online]. 2012, vol.9, n.2, pp.75-86. ISSN 1794-4449.

Introduction. Curcumin is the main colorant that can be found in the Cúrcuma longa's rhizome, in which there are also small quantities of other compounds insoluble in water, so its use in a puré state is not ideal. Curcumin is used, principally, dissolved with a mixture of alimentary degree solvents that allow its emulsification. This way, the product has a 4 - 10% of curcumin contení, miscible in water. Other forms of commercialization are also known, including the suspensión in vegetable oil and dispersión of this colorant in starch. It has also been demonstrated that cyclodextrin (CD) can be used as a solubilizing agent for hydrophobic volatile oils. It is formed by a hydrophilic external surface and an infernal hydrophobic cavity, which provides a capacity to form inclusión complexes with a variety of guests. These characteristics suggest that CD can be used to increase the solubility of hydrophobic and insoluble curcumin in water. Additionally, microencapsulation protects curcumin against destructive changes and allows itto flow freely when presented as powder. In this study, βCD and CD were evaluated as encapsulation agents for curcumin. Objective. Obtaining the cyclodextrin-curcumine complex as a substitute of tartrazine. Materials and methods. To develop this research work, 3 experiments were performed: In experiment 1 the effect of the concentration and of the type of solvent on the curcumin's absorption was studied for different solvents; water, ethanol, acetone, hexane, propylene glycol, ethyl lactate and ethylene glycol. Aqueous solutions were prepared in %v/v at 20%, 50%, 80%, 90% for each of the aforementioned solvents. The final concentration of the curcumin colorant was taken to 0.005%. In experiment 2 the association and the stoichiometric ratio between curcumin and two cyclodex-trins, β-ciclodextrina (β-CD) and γ-ciclodextrina (γ-CD), were determined. Two cyclodextrin solutions in the rank 0 - 0.02M, were used for that, plus a constant curcumin concentration of 0.001M, by means of agitation and heating at 50°C during 48 hours. In experiment 3, independent solutions of both cyclodex-trins were prepared in the presence of curcumin and the physical mixture and the coprecipitation methods were used to obtain the curcumin-cyclodextrin complex. A subsequent Differential Scanning Calorimetry analysis (DSC) was performed to corrobórate the formation of the complex. Results. The results demónstrate that the máximum absorbance of the curcumine takes place at a 425nm wavelength in the presence of a solution of ethanol:water at 20% (v/v). On the other hand, β-cyclodextrin (β-CD) reacts with curcumin to form a host-guest complex 1:1 with an apparent formation constant of 5,00x102 mol/L. The y-cyclodextrin (γ-CD) reacts with curcumin to form a host-guest complex 1:1 with an apparent formation constant of 7,51x103 mol/L. The complex is obtained at a laboratory level with best results by the use of the coprecipitation method, with 85% of performance for y-CD, and 69% for β-CD, so the most adequate cyclodextrin is γCD. Conclusions. Curcumin forms inclusión complexes with βCD and γCD in solution. The solubility of curcumin in the presence of βCD and γCD has demonstrated a higher effectiveness in the second one. The association of both cyclodextrins is 1:1, a fact that indicates that it is stronger with yCD due to its structure (8 units of glucose). The DSC analysis demonstrates that the inclusión complexes by physical mixture and by coprecipitation were formed. Nonetheless, for solubility effects, coprecipitation is more recommended because there is a prehydration.

Keywords : curcumin; cyclodextrin; complex; formation constant; solubility; absorbance; solvents.

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