Browsing by Autor "Juan-Antonio Alvarado"

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Model for measuring light stability of photolabile substances in powder beds using spray dried bixin microcapsules
(Elsevier BV, 2021) Cecilia K. Curi-Borda; Vandana Tannira; Niko Gentile; Juan-Antonio Alvarado; Björn Bergenståhl
Light stability of different spray dried microencapsulated powders containing the natural colorant bixin was evaluated for 30 days. The encapsulating materials evaluated were sucrose, maltodextrin, and mixtures including gum arabic and pectin as encapsulation enhancers. The photostability of two sets of encapsulated material was compared: one containing purified bixin, and one being an annatto extract composed of bixin and native carbohydrates. The photodegradation of bixin was monitored by vis-spectroscopy and HPLC. The observed degradation was 30–70 times slower compared to unprotected colorants. A model was established for describing the degradation process of the colorant in a solid particle form presented as powder beds. It was concluded that encapsulation in combination with light scattering by the matrix structure had a significant effect on the protection of the colorant. The overall enhancement of bixin stability towards UVA-visible light can be attained by microencapsulation through spray-drying. A correlation was observed between encapsulation efficiency and improved photostability of the colorant.
Multilayer Bixin Microcapsules: The Impact of Native Carbohydrates on the Microencapsulation Efficiency and Dispersion Stability
(Multidisciplinary Digital Publishing Institute, 2019) Cecilia K. Curi-Borda; Javier A. Linares‐Pastén; Tuba Tat; Rosmery Tarqui-Dueñas; Ninoska Chino-Flores; Juan-Antonio Alvarado; Björn Bergenståhl
Bixin is a hydrophobic carotenoid present in the integument of the seeds of <i>Bixa orellana</i>. Microencapsulation was applied to obtain water dispersible formulations and protect the colorant against degradation. Microencapsulated systems were obtained by spray-drying a mild alkaline bixin dispersion with different encapsulating materials. The encapsulation trials were performed with and without native carbohydrates of the integument in addition to the main encapsulant. It was possible to dry dispersions with up to 10% bixin counted on total solids. All the studied systems were characterized by colorimetry, UV-vis spectroscopy, Scanning Electron Microscopy, light microscopy, turbidometric sedimentation analyses and laser light diffraction analyses. All the systems showed aqueous dispersibility but displayed differences in their transparency, UV-vis spectra and physical stability at pH 3. The results show that the native carbohydrates enhance the encapsulation efficiency of other encapsulating materials. The chemical composition of this native carbohydrate fraction shows the presence of polysaccharides containing arabinose, galactose and glucose as monomers. Starch was identified enzymatically. The native carbohydrates allowed the encapsulation of bixin in its native microcrystalline form, resulting in a multilayer structure after spray-drying. In addition, the colorant particles displayed dispersibility under acidic aqueous conditions suggesting that they are stabilized by the native carbohydrates after the microcapsules are dissolved.