Freeze-Drying for Microencapsulation of Turmeric Oleoresin Using Modified Starch and Gelatin

Abstract

The aims of this study were to assess the turmeric oleoresin microencapsulation by freeze-drying with modified starch/gelatin and to evaluate its stability during storage at different temperatures and light. Encapsulated turmeric oleoresin w stored at −20, 25 and 60C, in the absence of light, and at 25C in the presence of light, and analyzed over a period of 6 weeks for curcumin and total phenolic contents and color. The different concentrations of wall material showed no significant effect on the curcumin retention. The best conditions for microencapsulation of turmeric oleoresin were: wall material composed of 30 g/100 g of modified starch + 1 g/100 g gelatin and mechanical homogenization. Encapsulated material was more stable during storage at −20C and less stable at 25C in the presence of light. Practical Applications Turmeric oleoresin, obtained by organic solvent extraction of turmeric (Curcuma longa L.), is a brownish-orange oily liquid used as a flavoring agent and a food color. However, despite the natural antioxidants content, turmeric oleoresin is sensitive to light, heat and oxygen. Furthermore, the oleoresins are immiscible in the aqueous medium, which makes difficult its use in food matrices. Encapsulation can solve some of these problems increasing stability and solubility of turmeric oleoresin. Use of freeze-drying on the encapsulation may be interesting as the low temperature of the process can minimize adverse chemical changes and transform the physical characteristics of turmeric oleoresin without providing significant losses related to bioactive compounds.