Food is any material consumed to provide nutrition to the organisms. In human body food is composed of body weight, bone, muscle mass, and other components, together with water. Food is the chief source of energy supply for all living things. The food that an animal eats supplies its daily energy needs through the food intake, for example, when a person is hungry he eats food to obtain food.
Basically, the human body consists of many types of living beings such as bacteria, single cell unicellular organisms (s cells), prokaryotes, eukaryotic, prokaryotic cells, and unicellular algae. Plants are the primary sources of food, which are composed of carbohydrate, protein, fat, mineral, and vitamins. Animal foods consist of meat, milk, eggs, organs, bones, fur, feathers, and so on. Food is divided into three categories: foods for animal nutrition, foods for plant nutrition, and foods for both animals and plants. Foods that are consumed by the animals are known as animal foods; those that are consumed by plants are called vegetable foods.
Generally, food processing techniques can be divided into two major categories: home processing and industrial processing. Home processing techniques mainly include usage of mechanical appliances for increasing the speed of food preparation; utilization of natural raw materials including vitamins, enzymes, salt, flour, and sugar. Industrial processing techniques mainly include use of chemicals and enzymes for increasing the rate of processing; use of surplus or extra virgin oil, ingredients, vitamins, etc., for prolonging the storage period of edible substances; separation of solids from liquids; addition of coloring, flavoring, or aroma agents; and production of food products that do not require further processing. After food processing, all the ingredients are cleaned thoroughly, sorted, and washed. Salt is also added for increasing the shelf-life of food.
The way food is cooked depends on the way it is eaten. Food that is eaten raw usually undergoes the process of dehydration (owing to a loss of vital nutrients) before being cooked. After this step, food is cooked using spices, butter, oil, tomatoes, onions, and other alkaline-base ingredients. On the other hand, food that is cooked using butter, oil, and tomatoes, is known as boiled food.
The way a food is stored after processing also depends on the way it is eaten. When food is stored in glass jars, for example, the nutrients within the jar are lost because of heat. On the other hand, food that is stored in metal containers such as cans, lids with lids, air-tight steel or aluminum cans, or glass jars is retained almost all of its nutritional value. Food that is preserved using salt or other chemicals (for example, acid or borate) is known as preservatives. In short, food processing involves the addition of varying amounts of nutrients to a food in order to prolong its shelf life; preservation entails adding chemicals to prevent deterioration and physical decay of food.
By eating foods that have been processed (such as junk food and chain restaurants), we do not get the necessary nutrients from our foods. In many cultures around the world, it has long been known that those who eat a lot of processed foods are more likely to develop chronic diseases such as diabetes, heart disease, and obesity. It stands to reason that if you want to live a long and healthy life, you should avoid eating too much junk food.