The latter half of the 20th century saw the use of vegetable stock become more common in professional kitchens. Vegetable stocks are used to prepare dishes for vegetarians, the health conscious, and for certain categories of soups. Apart from first sweating the vegetables in oil or butter before adding the liquid, the preparation of a vegetable stock follows the main principles of other white stocks. Sometimes, the pure juice of the vegetables is added to enhance or concentrate the stock’s flavor depending on its final use.