Microencapsulation of natural polyphenolic compounds extracted from apple peel and its application in yoghurt

Background. Apple peel is a by-product of fruit processing and a rich source of natural antioxidants, especially of polyphenolic compounds. Although it has many health benefits, the microencapsulation of polyphenolic compounds protects it from reactions with milk components during manufacturing or storage of dairy products which reduce the bioavailability and total acceptability of these products. Materials and methods. Polyphenolic compounds (PC) were extracted from apple peel using ethanol (80%). Polyphenolic compounds extract powder (PCEP) was encapsulated by physical methods (spray and freeze dryer) using maltodextrin, whey protein concentrate (8:2), and Gum Arabic mixture (6:4) as coating materials, which were homogenized by ultraturrax and ultrasonication. Encapsulated PCEP was used in supplementing yoghurt. Phenolic content (PC), physiochemical and texture properties of yoghurt samples were evaluated during storage (fresh, 7 and 15 days). Results. The microencapsulation by freeze dryer method for PCEP which was homogenized by ultrasonication was the best treatment, while encapsulation efficiency using the spray dryer method, which was homogenized by ultraturrax, was the worst. Encapsulated PCEP in yoghurt samples didn't have any significant influence on the physiochemical and texture properties of these samples. Conclusion. Yoghurt samples maintained on the polyphenolic compounds until the end of storage overall, our results revealed that adding encapsulated PCEP into yoghurt gave closer characteristics to the control sample.