This study investigates clove (CEO) and thyme (TEO) essential oils as natural preservatives, focusing on their composition, antimicrobial and antioxidant properties, and application in buttermilk. In the first part, GC-MS analysis identified eugenol (73.45%) and thymol (27.53%) as the major bioactive compounds in CEO and TEO, respectively. Antioxidant activity assays revealed strong performance for CEO, with EC