There tomato puree it is the heart of many Italian recipes, yet a pinch of it is enough acidity moreover to put even the most passionate cook into crisis. The taste of tomato and puree is a delicate balance between sugars and acids present within it: the natural presence of acids, such as malic and citric acid, and the state of ripeness can in fact influence the final flavour. Furthermore, other compounds can form during cooking, such aspyroglutamic acid (PCA), which can increase the acidity of the puree and give a unpleasant taste. There are two main home methods to correct acidity. The bicarbonate of sodium(NaHCO3) reacts with acids via a neutralizationforming carbonic acid which then decomposes into water and carbon dioxide, reducing Really the acidity. The sugar instead it does not react directly with acids but masks the flavor: the sucrose balances the presence of acids and binds to the receptors of the taste buds, compensating for the acidic sensation. Both methods make the paste more balanced, but through different mechanisms.
Tomato puree: between sugars and acids
There tomato puree it is a typical food of Italian cuisineobtained from the processing of fresh tomatoes. Traditionally it is prepared by cooking ripe tomatoes, removing the skin and seeds and then passing them – that is, sieving them – until a smooth, dense and homogeneous sauce is obtained. Tomatoes are fruits that contain high levels of sugars And organic acids. Among the main sugars we find fructose And glucosewhile for acids we have malic acid And citric acidwith the latter tending to diminish its quantity as maturation progresses, while the quantity of malic acid tends to remain almost unchanged. The balance between these two classes of substances affects the final flavor of the puree, and strongly depends on the stage of development and maturation of the tomatoes used.
Furthermore, an overall increase in the amount of organic acids can occur during the heat treatment of tomatoes. For example, the degradation of glutamine (an amino acid) leads to the formation of an acid called pyroglutamic acid (PCA), which can influence the final flavor of the tomato puree, also giving it a sour and unpleasant flavour.
How sugar works to cover the acidity of the sauce
One of the best known remedies for tomato puree that is too acidic is to add more sugar. The classic table sugar is nothing other than sucrosea disaccharide consisting of the union of two simple carbohydrates, the glucose and the fructose. When it comes into contact with our tongue, sucrose binds to its specific receptors present in the tongue taste budscreating a sweet taste and attenuating the acidity. So sucrose and acids do not “cancel” each other, but they do they compensate sensorially creating a more harmonious and pleasant balance, leaving the concentration of acids present in the puree unchanged.
How to use baking soda to neutralize acidity
Another technique involves adding a little bit of baking soda to neutralize the acids naturally present in the tomato. From a chemical point of view, it is a reaction between two classes of substances: the acids and the bases. Acids, including those naturally present in tomatoes, tend to release protons into solution (H ions+), while the basics, such as baking sodatend to capture these released protons. When we add bicarbonate to tomato puree, we are causing a base to react together with all the acids present in the food: acids and bases establish a specific reaction between them known as neutralization reaction. In this process, the H+ acids react with bicarbonate to form carbonic acid (H2CO3), which then decomposes into water and carbon dioxide.
The acids are thus transformed into neutral substances (this is why we talk about “neutralization”) and the total amount of acidity present in the puree decreases.
