Preparation and antioxidant activity evaluation of tea polyphenol–collagen–alginate microspheres

Abstract

Tea polyphenol (TP)-loaded alginate–collagen microspheres were prepared by ionic gelation method by Ca2+ as a cation and alginate as an anion. The morphology of the prepared microspheres was characterized by scanning electron microscopy. TP appeared in an amorphous state with an average size of 510.26 μm when encapsulated in the microspheres. The loading capacity (LC%) and encapsulation efficiency (EE%) were about 5.11% (w/w) and 33.51%, respectively. These microencapsulated beads were evaluated as a pH-sensitive system for the delivery of tea polyphenol. At pH 7.4, the amounts of TP released increased significantly as compared with those released at pH 1.2. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity and the stability of the microencapsulated TP were higher than that of free TP. Overall, the TP microspheres could improve antioxidant activity and the storage stability of TP at room temperature for 6 months. Practical applications TP is widely used in the food industry, medicine, and daily health care because of its antioxidant and antibacterial effects. However, TP is sensitive to temperature, light, pH, oxygen, etc., which risks its stability during processing, storage, and transportation. The encapsulation using microspheres is of great significance for improving the antioxidant activity of TP. In conclusion, microspheroidization is an attractive approach to preserving TP efficiency during food processing and enables a targeted delivery upon consumption.