There is a consensus among people that, when buying a soft drink, the first thing you should do when you get home is to place it inside the refrigerator so that it can be cooled. But what is the real need to perform this procedure?
This is done because of the role played by the gas in the refrigerant. No matter the brand or the flavor, when placing it in the fridge to cool down, we allow the gas present in the drink to dissolve in the water. This dissolution is related to an improvement in taste and a decrease in pH (making the medium more acidic) .
The gas that is added to the refrigerant is carbon dioxide (CO2). When this gas dissolves in water (carbonation), it forms a substance of formula H2CO3, O acid carbonic. It is noteworthy that the addition of CO2 in water it occurs with a certain pressure, which favors its dissolution.
Carbonic acid, being an acid, has a sour taste, which changes the taste of the syrup which is used in the production of the refrigerant. In addition to changing the flavor, carbonic acid
promotes a slight decrease in the pH of the soda by being a weak acid. This decrease in pH acts as an antibacterial, since the presence of the acidic environment prevents the proliferation of aerobic bacteria or any other aerobic micro-organism.Like carbonic acid too is an unstable acid (transforms spontaneously into other substances (H2O and CO2)), over time, it turns into carbon dioxide and water, especially if the refrigerant is kept in high temperature locations. So much so that when we open a bottle or can with soda at room temperature, we notice leaving a large amount of gas and changing its flavor (less tasty than if it were ice cold).
When we cool the soda, we provide the ideal condition for the carbon dioxide to dissolve in the water (the lower the water temperature, the more carbon dioxide will be dissolved). When it dissolves, as already pointed out, it forms carbonic acid, favoring a more pleasant taste to the soda than when it is hot.
The gas in the soda still has a refreshing action because the drink is consumed cold. During the journey from the mouth to the stomach, its temperature is elevated, which causes the carbonic acid to decompose into CO2. When eliminated, the CO2 promotes a feeling of freshness because of its expansion in the digestive tract.
By Me. Diogo Lopes Dias
Source: Brazil School - https://brasilescola.uol.com.br/quimica/importancia-gas-no-refrigerante.htm