Encapsulation of felty germander (Teucrium polium L.) extract using the freeze-drying method

Extracts with antimicrobial and antioxidant properties are limited in their application in food products due to their inability to withstand harsh environmental conditions, such as high temperatures and oxygen exposure. Therefore, the present study investigated the nanoencapsulation of Teucrium polium L. extract using the freeze-drying method to facilitate its application and protection against environmental factors. In this regard, an emulsion containing Teucrium polium L. extract at concentrations of 10%, 20%, and 30% and a mixture of maltodextrin/Persian gum in three ratios of 1:2, 1:1, and 2:1 as the coating wall were produced and then dried in a freeze dryer. In the following, the properties of emulsions and produced nanocapsules were studied. According to the results, emulsions with high amounts of Persian gum showed more stability, zeta potential, and viscosity. However, their particle size and polydisparity index were lower than those of other emulsions. As the extract concentration increased, there was a decrease in stability, zeta potential, and viscosity, accompanied by an increase in particle size and polydispersity index. Concurrently, elevated concentrations of maltodextrin, Persian gum, and extract resulted in higher humidity, density, encapsulation efficiency, and antioxidant activity of the capsules. The most optimal properties of emulsions and nanocapsules were achieved at the 10% concentration of Teucrium polium L. extract and the 1:1 ratio of maltodextrin/Persian gum mixture as the wall material. It is noteworthy that the release rate of phenolic compounds reached its maximum value (88%) after 60 days.