Foods are processed in order to make them more palatable and safe to eat, to increase their shelf life and to add variety and convenience to our diets. Food processing is an important and necessary step to convert raw agricultural products into foods that are both economical and convenient. Unfortunately, agricultural production is a seasonal activity while food consumption occurs year round. Actually, the major component of most foods is water. Vitamins and other minor constituents are called microcomponents.
Calories are a way of expressing the fuel value of food.
More recently, the unit of choice has become the joule which equals 0.239 calories. Proteins, carbohydrates and fats all contribute to the caloric value of a food, but fat carries more than twice the calories of the other two components, about 9 calories per gram. Food analysis is a significant part of Food Science. There are standardized tests for all the major and minor components found in food. For example, a common way to measure water in a food sample is to remove the water by drying and express the weight loss as moisture.