Cooking requires applying heat to a food which usually, though not always, chemically changes the molecules, thus changing its flavor, texture, appearance, and nutritional properties.[88] Cooking certain proteins, such as egg whites, meats, and fish, denatures the protein, causing it to firm. There is archaeological evidence of roasted foodstuffs at Homo erectus campsites dating from 420,000 years ago.[89] Boiling as a means of cooking requires a container, and has been practiced at least since the 10th millennium BC with the introduction of pottery.[90]
Some people have allergies or sensitivities to foods which are not problematic to most people. This occurs when a person's immune system mistakes a certain food protein for a harmful foreign agent and attacks it. About 2% of adults and 8% of children have a food allergy.[140] The amount of the food substance required to provoke a reaction in a particularly susceptible individual can be quite small. In some instances, traces of food in the air, too minute to be perceived through smell, have been known to provoke lethal reactions in extremely sensitive individuals. Common food allergens are gluten, corn, shellfish (mollusks), peanuts, and soy.[140] Allergens frequently produce symptoms such as diarrhea, rashes, bloating, vomiting, and regurgitation. The digestive complaints usually develop within half an hour of ingesting the allergen.[140]
Edible animal material, including muscle, offal, milk, eggs and egg whites, contains substantial amounts of protein. Almost all vegetable matter (in particular legumes and seeds) also includes proteins, although generally in smaller amounts. Mushrooms have high protein content. Any of these may be sources of essential amino acids. When proteins are heated they become denatured (unfolded) and change texture. In many cases, this causes the structure of the material to become softer or more friable – meat becomes cooked and is more friable and less flexible. In some cases, proteins can form more rigid structures, such as the coagulation of albumen in egg whites. The formation of a relatively rigid but flexible matrix from egg white provides an important component in baking cakes, and also underpins many desserts based on meringue.
Outstanding vintages from the best vineyards may sell for thousands of dollars per bottle, though the broader term "fine wine" covers those typically retailing in excess of US$30–50.[98] "Investment wines" are considered by some to be Veblen goods: those for which demand increases rather than decreases as their prices rise. Particular selections have higher value, such as "Verticals", in which a range of vintages of a specific grape and vineyard, are offered. The most notable was a Château d'Yquem 135 year vertical containing every vintage from 1860 to 2003 sold for $1.5 million. The most common wines purchased for investment include those from Bordeaux and Burgundy; cult wines from Europe and elsewhere; and vintage port. Characteristics of highly collectible wines include:
Some countries list a legal definition of food, often referring them with the word foodstuff. These countries list food as any item that is to be processed, partially processed, or unprocessed for consumption. The listing of items included as food include any substance intended to be, or reasonably expected to be, ingested by humans. In addition to these foodstuffs, drink, chewing gum, water, or other items processed into said food items are part of the legal definition of food. Items not included in the legal definition of food include animal feed, live animals (unless being prepared for sale in a market), plants prior to harvesting, medicinal products, cosmetics, tobacco and tobacco products, narcotic or psychotropic substances, and residues and contaminants.[158]
Restaurants employ chefs to prepare the food, and waiters to serve customers at the table.[99] The term restaurant comes from an old term for a restorative meat broth; this broth (or bouillon) was served in elegant outlets in Paris from the mid 18th century.[100][101] These refined "restaurants" were a marked change from the usual basic eateries such as inns and taverns,[101] and some had developed from early Parisian cafés, such as Café Procope, by first serving bouillon, then adding other cooked food to their menus.[102]
In the 20th century, supermarkets were born. Supermarkets brought with them a self service approach to shopping using shopping carts, and were able to offer quality food at lower cost through economies of scale and reduced staffing costs. In the latter part of the 20th century, this has been further revolutionized by the development of vast warehouse-sized, out-of-town supermarkets, selling a wide range of food from around the world.[117]
Certain exceptions to the ban on alcohol apply. Alcohol derived from a source other than the grape (or its byproducts) and the date[115] is allowed in "very small quantities" (loosely defined as a quantity that does not cause intoxication) under the Sunni Hanafi madhab, for specific purposes (such as medicines), where the goal is not intoxication. However, modern Hanafi scholars regard alcohol consumption as totally forbidden.[116]
"Seasonal" here refers to the times of year when the harvest or the flavour of a given type food is at its peak. This is usually the time when the item is harvested, with some exceptions; an example being sweet potatoes which are best eaten quite a while after harvest. It also appeals to people who prefer a low carbon diet that reduces the greenhouse gas emissions resulting from food consumption (Food miles).

Cooking can prevent many foodborne illnesses that would otherwise occur if the food is eaten raw. When heat is used in the preparation of food, it can kill or inactivate harmful organisms, such as bacteria and viruses, as well as various parasites such as tapeworms and Toxoplasma gondii. Food poisoning and other illness from uncooked or poorly prepared food may be caused by bacteria such as pathogenic strains of Escherichia coli, Salmonella typhimurium and Campylobacter, viruses such as noroviruses, and protozoa such as Entamoeba histolytica. Bacteria, viruses and parasites may be introduced through salad, meat that is uncooked or done rare, and unboiled water.[19]
Food is any substance[1] consumed to provide nutritional support for an organism. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ingested by an organism and assimilated by the organism's cells to provide energy, maintain life, or stimulate growth.