Microencapsulation of xanthan gum based on palm stearin/beeswax matrix as wall system

摘要

Xanthan gum microcapsules (XGMC) were prepared by phase separation method based on palm stearin/beeswax (PS/BW) systems. XG microcapsules with high encapsulation efficiency were obtained at the preparation conditions of PS-to-BW ratio 7:3 and core-to-wall ratio 10:10. The inverted micrograph showed that the shapes of XGMC were mainly spherical, and the particle sizes of XGMC were chiefly distributed in the range from 40 to 300 mu m. The XGMC curve of differential scanning calorimetry (DSC) illustrated that two peaks appeared at around 40 and 60 degrees C, and the two temperatures were in accordance with the melting points of PS and BW, respectively. Compared with that of XG, the hygroscopicity of XG in microcapsules was obviously decreased under medium and high humidity conditions. Viscosity measurements showed that XGMC could be destructed and XG was completely released from microcapsules at temperature above 65 degrees C. The XG released from microcapsules could more fast hydrate than XG, and "fish-eye" would not be formed. Microencapsulation could be an effective method to protect XG from high hygroscopicity, to promote the polysaccharide hydration process, and to prevent the "fish-eye" formation. Practical Applications XG as a hydrophilic polysaccharide is able to strongly absorb moisture and form agglomerates during storage. Moreover, the gum tends to produce "fish-eye" formation during hydration process. These shortcomings are not propitious for XG applications in the food processing industry. Microencapsulation is usually employed to improve the physicochemical properties of active ingredients. XG was encapsulated into palm stearin/beeswax matrix using phase separation method. The hygroscopicity of XG was reduced significantly after microencapsulation, and the "fish-eye" formation was also effectively prevented. The hydration rate and efficiency of XG after microencapsulation were obviously enhanced. The XG microcapsules obtained in this work will promote the application in food industry and increase the economic value of XG. In addition, the system of palm stearin/beeswax could be adequately developed as effective wall materials.