TPO - If you've ever wanted to know exactly what's in your packaged food, you're probably familiar with the black and white nutrition chart on food labels. This chart provides data on calories, protein, fat, and other nutrients. But have you ever wondered how these numbers are measured?
Foods are categorized into three main macronutrients: protein, fat, and carbohydrates. These are the basic components that the body needs, and each is measured in distinct ways.
Protein is measured based on its nitrogen content, because protein contains nitrogen, while other nutrients do not. The nitrogen content is multiplied by a factor of 6.25 (since protein typically contains around 16% nitrogen) to determine the protein content. The two main methods for measuring nitrogen are the Kjeldahl method and the Dumas method, with the Kjeldahl method based on analyzing the amount of ammonia released from a food sample.
- Fat content is determined by its solubility in organic solvents such as ether or chloroform. The difference in weight of the food sample before and after treatment with this solvent is the amount of fat.
However, this method is time-consuming and can be less accurate, so more advanced techniques such as nuclear magnetic resonance and ultrasound are gradually becoming alternatives, despite the higher cost.
Carbohydrates are the body's primary source of energy—often measured indirectly by subtracting the weight of other substances such as protein, fat, water, ash, and alcohol from the total weight of the food.
Finally, to calculate calories, a traditional method was to use a bomb calorimeter, where food was burned and the changing water temperature indicated the calorie count. However, this method is now less commonly used due to its high cost and potential for inaccurate results. Instead, the Atwater system is preferred, which calculates calories from each energy-containing nutrient.
Many people question whether we can trust manufacturers not to exaggerate the nutritional content of their products.
While there isn't much scientific evidence to support this claim, today we have more accurate methods for calculating nutritional content, as well as convenient online databases and nutritional analysis services to give consumers greater peace of mind.
According to Science ABC II
Source: https://tienphong.vn/thanh-phan-dinh-duong-tren-bao-bi-thuc-pham-co-dang-tin-post1678123.tpo
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