A functional food is a food given an additional function (often one related to health-promotion or disease prevention) by adding new ingredients or more of existing ingredients. The term may also apply to traits purposely bred into existing edible plants, such as purple or gold potatoes having enriched anthocyanin or carotenoid contents, respectively. Functional foods may be "designed to have physiological benefits and/or reduce the risk of chronic disease beyond basic nutritional functions, and may be similar in appearance to conventional food and consumed as part of a regular diet".
Certain cultures highlight animal and vegetable foods in a raw state. Salads consisting of raw vegetables or fruits are common in many cuisines. Sashimi in Japanese cuisine consists of raw sliced fish or other meat, and sushi often incorporates raw fish or seafood. Steak tartare and salmon tartare are dishes made from diced or ground raw beef or salmon, mixed with various ingredients and served with baguettes, brioche, or frites. In Italy, carpaccio is a dish of very thinly sliced raw beef, drizzled with a vinaigrette made with olive oil. The health food movement known as raw foodism promotes a mostly vegan diet of raw fruits, vegetables, and grains prepared in various ways, including juicing, food dehydration, sprouting, and other methods of preparation that do not heat the food above 118 °F (47.8 °C). An example of a raw meat dish is ceviche, a Latin American dish made with raw meat that is "cooked" from the highly acidic citric juice from lemons and limes along with other aromatics such as garlic.
Types of fat include vegetable oils, animal products such as butter and lard, as well as fats from grains, including maize and flax oils. Fats are used in a number of ways in cooking and baking. To prepare stir fries, grilled cheese or pancakes, the pan or griddle is often coated with fat or oil. Fats are also used as an ingredient in baked goods such as cookies, cakes and pies. Fats can reach temperatures higher than the boiling point of water, and are often used to conduct high heat to other ingredients, such as in frying, deep frying or sautéing. Fats are used to add flavor to food (e.g., butter or bacon fat), prevent food from sticking to pans and create a desirable texture.
For people who are healthy, a healthy diet is not complicated and contains mostly fruits, vegetables, and whole grains, and includes little to no processed food and sweetened beverages. The requirements for a healthy diet can be met from a variety of plant-based and animal-based foods, although a non-animal source of vitamin B12 is needed for those following a vegan diet. Various nutrition guides are published by medical and governmental institutions to educate individuals on what they should be eating to be healthy. Nutrition facts labels are also mandatory in some countries to allow consumers to choose between foods based on the components relevant to health.
In the pre-modern era, the sale of surplus food took place once a week when farmers took their wares on market day into the local village marketplace. Here food was sold to grocers for sale in their local shops for purchase by local consumers. With the onset of industrialization and the development of the food processing industry, a wider range of food could be sold and distributed in distant locations. Typically early grocery shops would be counter-based shops, in which purchasers told the shop-keeper what they wanted, so that the shop-keeper could get it for them.
^ Smithers, Rebecca (February 10, 2012). "Sainsbury's changes food freezing advice in bid to cut food waste". The Guardian. Retrieved February 10, 2012. Long-standing advice to consumers to freeze food on the day of purchase is to be changed by a leading supermarket chain, as part of a national initiative to further reduce food waste. [...] instead advise customers to freeze food as soon as possible up to the product's 'use by' date. The initiative is backed by the government's waste advisory body, the Waste and Resources Action Programme (Wrap) [...] Bob Martin, food safety expert at the Food Standards Agency, said: "Freezing after the day of purchase shouldn't pose a food safety risk as long as food has been stored in accordance with any instructions provided. [...]"
An emulsion of starch with fat or water can, when gently heated, provide thickening to the dish being cooked. In European cooking, a mixture of butter and flour called a roux is used to thicken liquids to make stews or sauces. In Asian cooking, a similar effect is obtained from a mixture of rice or corn starch and water. These techniques rely on the properties of starches to create simpler mucilaginous saccharides during cooking, which causes the familiar thickening of sauces. This thickening will break down, however, under additional heat.
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. 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. 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.
Freeze-drying requires the use of heavy machinery and is not something that most campers are able to do on their own. Freeze-dried ingredients are often considered superior to dehydrated ingredients however, because they rehydrate at camp faster and retain more flavor than their dehydrated counterparts. Freeze-dried ingredients take so little time to rehydrate that they can often be eaten without cooking them first and have a texture similar to a crunchy chip.