Many of the principles of sanitation and sanitary design in food processing have been developed by the dairy industry. The design and operation of a dairy is largely directed at preventing these undesirable events while maximizing the efficient production of high-quality products. As with pasteurization, homogenization has been applied outside the dairy industry, to produce such products as salad dressings and sauces, but its largest application is still milk and other dairy fluids. The flavors typically arise from certain feeds eaten by dairy cattle, such as wild onion, wild garlic, or other odiferous herbs or weeds. One of the most popular dairy products is ice cream in its many variations. The manufacture is relatively simple, but there are some interesting issues. Since ice cream is sold by volume, and not by weight, there is an understandable temptation to incorporate as much air as possible, since it is less expensive than butterfat, milk solids and sugar.