Basil is one of the most often used herbs in Mediterranean cooking. Although basil is one of the most well known and most often used herbs, many different varieties of basil actually exist which differ in appearance and in flavor. However, once picked the leaves will wilt quickly and lose most of their scent and flavor. Basil is a delicate plant that changes flavor when it is dried (it takes on a lighter minty aspect). It also darkens when put in the freezer or refrigerator. Olive Oil is the best way to conserve fresh basil. O&CO. basil is totally fresh, it is olive oil which conserves it, so you can enjoy the lively and special flavor of basil all year long.