In addition, many cultures use grills for cooking. A grill operates with a radiant heat source from below, usually covered with a metal grid and sometimes a cover. An open pit barbecue in the American south is one example along with the American style outdoor grill fueled by wood, liquid propane, or charcoal along with soaked wood chips for smoking. A Mexican style of barbecue is called barbacoa, which involves the cooking of meats such as whole sheep over an open fire. In Argentina, an asado (Spanish for "grilled") is prepared on a grill held over an open pit or fire made upon the ground, on which a whole animal or smaller cuts are grilled.
Wine cellars, or wine rooms, if they are above-ground, are places designed specifically for the storage and aging of wine. Fine restaurants and some private homes have wine cellars. In an active wine cellar, temperature and humidity are maintained by a climate-control system. Passive wine cellars are not climate-controlled, and so must be carefully located. Because wine is a natural, perishable food product, all types—including red, white, sparkling, and fortified—can spoil when exposed to heat, light, vibration or fluctuations in temperature and humidity. When properly stored, wines can maintain their quality and in some cases improve in aroma, flavor, and complexity as they age. Some wine experts contend that the optimal temperature for aging wine is 13 °C (55 °F), others 15 °C (59 °F).
Most wines are sold in glass bottles and sealed with corks (50% of which come from Portugal). An increasing number of wine producers have been using alternative closures such as screwcaps and synthetic plastic "corks". Although alternative closures are less expensive and prevent cork taint, they have been blamed for such problems as excessive reduction.
Most food has its origin in plants. Some food is obtained directly from plants; but even animals that are used as food sources are raised by feeding them food derived from plants. Cereal grain is a staple food that provides more food energy worldwide than any other type of crop. Corn (maize), wheat, and rice – in all of their varieties – account for 87% of all grain production worldwide. Most of the grain that is produced worldwide is fed to livestock.