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Special food | Permeable and isotonic food
Date: 2024-12-16Read: 1
The minimum additional pressure applied on the high concentration side to prevent water from penetrating from the low concentration side to the high concentration side due to the different concentrations of the aqueous solution on both sides of the semi permeable membrane is called osmotic pressure (molar osmotic pressure, molar osmotic pressure). The osmotic pressure (molar concentration osmotic pressure, molar osmotic pressure) is related to the number of particles in the solution that cannot pass through the semi permeable membrane and the ambient temperature.
What is isotonic food?
Isotonic food refers to food that has an osmotic pressure (molar concentration osmotic pressure, molar osmotic pressure) similar to that of normal human body fluids in a ready to eat state. When our body digests food, the secreted gastric juice mixes with the digested food, forming a fairly uniform liquid chyme under the contraction of stomach muscles. The digestion process in the stomach takes a long time, waiting for these liquid substances to reach an osmotic state before entering the small intestine and being absorbed by the human body. However, when consuming isotonic foods, such foods enter the stomach in a basically isotonic state, greatly shortening the time the food stays in the stomach, reducing the decay of nutrients, and also allowing them to enter the small intestine more quickly for absorption by the body, improving the efficiency of nutrient absorption. The latest version of China's regulations on isotonic foods includes the "Isotonic Foods" (QB/T 5727-2022) released in 2022. The requirements for osmotic pressure of isotonic food in ready to eat state are as follows:
Note: The unit is milliosmolar moles per liter, i.e. mOsmol/L
How to detect osmotic pressure?
For the determination of osmotic pressure (molar concentration osmotic pressure, molar osmotic pressure), the commonly used method is to indirectly measure the osmotic pressure molar concentration of a solution by using the freezing point descent method, as the ideal solution's freezing point drop and mean osmotic pressure are proportional to the weight molar concentration of the solution. Appendix A of the standard "Isotonic Foods" (B/T5727-2022) provides detailed instructions on the determination methods of osmotic pressure for liquid, solid, and semi-solid common foods. For special foods, the State Administration for Market Regulation issued the "Determination of Osmotic Pressure of Special Foods" (BJS 202102) in 2021, which also provides detailed instructions on the determination of osmotic pressure in infant formula, special medical use infant formula, and special medical use formula. Because the measurement unit of commonly used freezing point osmometers (molar concentration osmometers, molar concentration measuring instruments) is m0smo1/kg, if the unit of osmotic pressure (molar concentration osmometers, molar osmotic pressure) is required to be mosmo1/L, a density meter/densitometer can be introduced to measure the density of the solution and perform unit conversion.
Overall, both methods mentioned above have been appropriately modified based on the osmotic pressure molar concentration determination method in Chinese Pharmacopoeia 0632.
Regulations on Label Identification
In QB/T 5727-2022 "6. Labeling" of isotonic foods, it is stipulated that:
6.1 Food that meets standard requirements may be labeled with words such as "isotonic", "isotonic food", or similar expressions on their product labels. For products labeled with "isotonic" or similar expressions, the label should also indicate the osmotic pressure (molar concentration osmotic pressure, molar osmotic pressure).
6.2 Non ready to eat isotonic foods should be clearly labeled with the mixing method and labeled as "non ready to eat"