Nutritional value is a set of properties of food products that provide the physiological needs of a person for energy and essential nutrients. The main source of energy for humans are proteins, fats and carbohydrates.
But they also necessarily include a large number of chemical compounds: vitamins, micro and macro elements, minerals, biologically active agents.
For everyone nutrition is the only source of energy and all these necessary elements that are required for the proper and full functioning of the body.
It is no secret that all the chemical compounds necessary for normal functioning enter the human body with food. These are substances whose role is to restore the expended energy in the process of life, provide building material for new cellular structures, as well as substances responsible for regulating complex life processes. It is important to note that all these substances, except for water, mineral salts and some low molecular weight compounds, before being directly involved in their direct purpose, undergo a process of splitting from the form in which they are presented in food products into a simpler form. As a result, in the future, they acquire the ability to participate in the necessary reactions occurring in various organs and tissues with the formation of all the substances necessary for the body.
Energy value is the amount of energy that comes from the biological oxidation of fats, proteins, carbohydrates, and other types of chemical structures found in foods. It can be expressed in kilocalories (kcal) or kilojoules (kJ).
Energy released during oxidation
- 1g of fat equals 9.0 kcal
- 1 g of carbohydrates - 3.75 kcal
- 1 g of proteins - 4.0 kcal
- 1g organic acids - 3.0 kcal/g
- 1 g of ethyl alcohol - 7.0 kcal/g.
To convert the energy value into SI units and vice versa, the following coefficient is used: 1 kcal = 4.184 kJ. The energy value of products is calculated per 100 g of the edible part. The theoretical caloric content is defined as follows. For each of the nutrients (proteins, fats and carbohydrates), you need to multiply the amount of energy they release by the percentage of the corresponding nutrients. The sum of the products obtained is the theoretical calorie content of 100 g of the product. From this, you can determine the calorie content of any amount (250g, 1.5kg, etc.). With a known theoretical calorie content the practical (actual) calorie content can be calculated by multiplying the result of the theoretical calorie content by the digestibility of each of the nutrients in percent and dividing the product by 100.
To determine the consumer properties of various products, the first step is to analyze their chemical composition and the properties of their constituent chemicals. According to the functional purpose and chemical composition, organic and inorganic substances that make up food products are divided into energy, plastic (water, proteins, fats, etc.) and volume-functional (vitamins, nitrogenous and enzymes).
Data on the chemical composition of products and food consumption norms make it possible to determine the range of products that can meet the body's need for nutrients in each particular case.
There are a number of basic consumer properties that are somehow useful to the consumer. Namely, nutritional, biological, energy and physiological value.
The nutritional value of the product characterizes the fullness of useful properties, i.e. its good quality, digestibility, content of nutrients and biologically active agents.
The presence of vitamins, macro- and microelements, essential amino acids and polyunsaturated fatty acids, which are not synthesized in the body and cannot be replaced by other nutrients, constitute the biological value of products.
Physiological value means the ability of products to influence the nervous, cardiovascular, digestive system of a person.
The presence of fats, proteins, carbohydrates and their digestibility characterize the energy value of food products.
What you need to know about energy value (EV)?
EV is the ability of food components that are part of food products to produce (release) heat (energy), which is formed at the final stage of oxidation of the constituent substances.
For food products, there are net and gross calories.
In the first case, this is the volume of carbohydrates, proteins and fats in the mass of the product that is absorbed by the body. As for gross calorie content - the indicator is an energy value that does not depend on oxidation of the ingredients.
Several methods are used to calculate the energy value.
In particular, these are:
- the physical - the technique involves burning the sample in a calorimeter (a vessel with thick walls and an inner vessel - a heat sink with water, a special stirrer and a thermometer). During measurements, the temperature (before and after the sample is burnt), the weight of the sample, and the volume of liquid used are determined. The final value is determined by the formula, taking into account the parameters obtained during the test;
- the chemical - for this method, the calculation of the content of carbohydrates, proteins and fats is carried out per 100 grams (or 100 ml) of the product, given that the mass of EV (physical/physiological) cannot exceed the nominal values (proteins should not exceed 4.0 Kcal, carbohydrates - should not be less than 3.75 Kcal, and fats should not exceed 9.0 Kcal);
- the tabular - is similar to the chemical method. The indicator is determined taking into account the parameters for determining the calorie content, which are indicated in the regulatory and technical documentation (handbooks, instructions and GOST (All-Union State Standard)
Which food groups are the most and which are the least caloric?
Products differ in energy value.
The calorie content of products of complex food compositions depends on their composition and recipe, the choice of raw materials with a lower or higher energy value, as well as on the technological processes used.
Foods containing the highest amount of fats and carbohydrates are the most high-calorie. The food group with the lowest calorie content is vegetable products.
Information about the energy value of a food product can be found on its pack.
Calculation of nutritional and energy value
One of the consumer’s rights is to receive reliable information about the food product, its composition and calorie content. That is why each manufacturer must perform an accurate calculation of the nutritional and energy value of the product and place the information obtained on the pack of the finished product.
How is the calorie content of foods reduced?
Among food products, there are many products with a reduced energy value. Their calorie content is reduced by reducing their fat and sugar content.
Another way to reduce the calorie content of food is to replace sugar and fat with substances with a low or no energy value.
For example, sugar can be replaced with polyol sweeteners (xylitol, maltitol), which have a lower calorie content than natural sugar (about 40%), or synthetic intense sweeteners (e.g., aspartame, thaumatin), which have no calories. It should be noted that there are certain rules that regulate sweeteners, in what dose and in what products their use is allowed.