CURCUMIN-BASED HYDROPHILIC COLORANTS USE IN BARKED MERINGUES

The use of natural coloring agents is a challenge for the food industry, even natural counterparts of synthetic colorants, e.g. tartrazine, are available in the market. Encapsulation has risen as a promising technique to improve the technological properties of curcumin, a yellow natural colorant, which presents low water solubility and low stability (e.g. to heat and pH). In this study, curcumin was encapsulated in polyvinyl alcohol (PVA), polyvinylpyrrolidone and k-carrageenan by the solid dispersion technique assisted by spray-drying. Water solubility of curcumin was greatly improved, being the particles readily dispersible in water. The physicochemical characterization (X-Ray Diffraction and Differential Scanning Calorimetry) has demonstrated that encapsulated curcumin presented an amorphous structure, while the Scanning Electron Microscopy images showed that PVA led to the formation of agglomerated particles. Cytotoxicity of the encapsulated curcumin was evaluated in in vitro tests using tumor (MCF-7- breast adenocarcinoma, NCI-H460- non-small cell lung carcinoma, HeLa- cervical carcinoma and HepG2- hepatocellular carcinoma) and non-tumor (PLP2- porcine liver primary) cell lines. The anti-inflammatory activity was also evaluated by murine macrophage cells. Results showed that encapsulated curcumin presented cytotoxicity against tumor cells even when no organic solvent was added, meaning that encapsulation improved its water affinity. Anti-inflammatory effects were also observed. To test the use of the produced encapsulated curcumin as a coloring agent, meringues were chosen as a prove of concept due to the required long baking time. Principal Components Analysis demonstrated that encapsulation improved the coloring power of curcumin while protecting against color loss during the baking process (100ºC, 2 h). Mechanical strength (determined by texture puncture test) decreased while an increase in pore sizes was detected due to the presence of the encapsulated curcumin. Gathered results demonstrated that encapsulated curcumin is a promising alternative to artificial colorants in baked foodstuff.