Microencapsulation in alginate for food. Technologies and applications

The objective of the work was to review the alginate microencapsulation techniques for food applications. Alginate has been one of the most widely used polymers in microencapsulation, the matrix forms a highly versatile, biocompatible and nontoxic for the protection of active components, cells or microorganisms sensitive to heat, pH, oxygen, light and others factors which are exposed to foods during processing and storage. The gelation process of calcium alginate for the preparation of the microcapsules is possible by two mechanisms of ionic gelation: external and internal gelation depending on whether the calcium is supplied from outside the capsule or whitin the same. For preparing calcium alginate microcapsules into food applications, there are techniques such as: extrusion, emulsion and spray drying. Althought spray drying has been a simple and economic process for industry, the application with alginate has been limited by the viscosity of solution and the speed og gelation. Moreover, the technique by extrusion has been traditionally used due of the homogeneity of the microcapsules in shape and sizes. While the emulsion technique has been used more recently, proving to be easy to apply and mass production. Nowadays new technologies are developed to decrease the size of the microcapsules thus extending its application in industry. Among the latest trends in microencapsulation, new systems are studied by using mixed polymers matrices in order to obtain combined physical-chemical properties, that allowing microencapsulation process being more efficient for the protection and controlled release of active ingredient.