Energy in food

Get to know the concept of food energy and the measurement units used to measure it. Relate them to the joule, the usual energy unit in physics that you have already learned. Answer the question.

What kind of energy are we talking about here

All living things need energy (metabolism). Plants produce their own energy from sunlight (they are autotrophs) - this process is called photosynthesis. Humans and animals are not capable of photosynthesis and get their energy from food (we are heterotrophs). Energy is stored in chemical bonds and is only released when these chemical bonds are broken.

In a very physics-like language, it can be said that inside us there is an oven with a very peculiar shape and construction, in which we constantly burn fuel, i.e. food, on a "small fire".

Calorie and kilocalorie

A calorie is a unit of energy. A calorie (denoted cal ) is the energy required to raise the temperature of one gram of water by one degree Celsius at normal pressure. 1 kilocalorie (denoted kcal ) is therefore the same size for a kilogram of water and is equal to calories,

Joule and calorie

In the International System of Units, the unit of energy is the joule. One calorie () is approximately equal to joules.

A person's daily energy needs

A person's daily energy requirement is between - kcal and depends on many different factors, such as physical activity, age, environmental temperature, hormonal status, etc. With the help of various calculators, we can also calculate our own energy needs.

What do we say about it

In food science, we still talk about the same energy, which has already been mentioned several times in this course. It is possible to easily convert calories into joules and place it in the context of the mind games discussed earlier. For example, you can seriously ask how many packets of halvah are needed to boil a liter of water. This may be a surprising fact for students.