So, what is the pH of the tomato? The pH of fresh tomatoes is in the range of 4.3 – 4.9, that is the tomatoes are acidic in nature. Different forms of tomato products will have different pH because of the additives added as well as the cooking process. The pH for canned tomatoes is in the range of 3.5-4.7, lower as compared to the fresh tomato because of the preservation agent that is added to make increase its shelf life. For tomato puree and tomato juice, the pH ranges between 4.1-4.6. The health benefits of tomatoes are because of nutrients such as folic acid, lutein, choline, lycopene, etc present in it. The percentage of these nutrients varies depending upon how close they are to maturity and how they are cooked. Therefore, it is very important for us to determine the pH of tomatoes, in order to quantify the nutritional value and thus the benefits. There are deeper dimensions to pH and especially pH of tomatoes which are very important in understanding the acidic nature, which is discussed as follows-
What makes tomatoes acidic in nature?
It is a very general rule of thumb in chemistry studies that the things acidic in nature taste sour and things alkaline or basic in nature taste bitter. Therefore, this test can be used as a preliminary checkpoint to determine the acidic or alkaline nature of food. As tomatoes taste sour, we can easily say that tomatoes are acidic in nature. But what exactly makes them acidic is the question we are trying to answer. Tomatoes contain folic acid, citric acid, ascorbic acid, and malic acid as well. All of these are weak organic acids which makes the tomatoes weakly acidic in nature. Initially, when the tomatoes are unripe and green, malic acid is the major component of all the acids that are present. As it comes closer to maturity and starts turning cherry red in color, the citric acid becomes the dominant one. Malic acid is a dicarboxylic acid present widely in fruits contributing to their sour test. It is very important for the human body as it is involved in the Krebs cycle, which is the energy-making process of a living body. However, it is very acidic in nature and if over-consumed can lead to acidity and heartburns. Hence, one should not have unripe tomatoes to such an extent that it creates problems in the body.
Citric acid is a tricarboxylic acid and weak organic acid which gives us the sour taste to most of the citrus fruits. It is present in tomatoes but in fewer quantities as compared to lemon, oranges, and other citrus rich foods. Citric acid also is an important intermediate responsible for the absorption of nutrients in the body.
What does pH conclude about tomatoes?
The pH talks about the acidity of the tomatoes which can be used as indicative of the extent of ripeness of the tomatoes. It has an inversely proportional relationship to each other; the ripeness of a tomato is inversely related to the acidity of it. For example, a tomato is riper then the pH will be closer to 5 and if it is less ripe then it will be closer to the 4.5-4.6 pH range. Therefore the tomatoes are bought after checking the pH which is in tracks to the end-use application of these tomatoes. For example, If a puree or sauce has to be made out of tomatoes, then less ripe tomatoes can be used since then additional additives and preservatives can be used to make up for this acidity. But if the tomatoes are required for making a juice or to be used as a fresh vegetable then completely ripe tomatoes are the correct choice.
Why do different tomato products have different pH?
The different types of tomato products available are fresh tomatoes, canned tomatoes, tomato puree, tomato sauce, and tomato soup. The difference in the pH is because of the process that the tomatoes undergo to get delivered as these final products. Canned products are typically more acidic in nature because there is a preservative added, also acidic in nature because of which the overall pH drops. The pH of canned tomatoes is 3.5. These preservatives supply enough acidity such that there is no growth of bacteria. If at all there is any growth, then it can be destroyed by quickly heating and cooling it. In the case of tomato puree, these preservatives are present in more quantity moreover the tomatoes are itself more acidic for this particular end-use, hence the pH is even lowered.
Is the acidity of tomatoes unpleasant/bad for human health?
There cannot be a perfect answer to this question as it is very much dependent on the individual’s digestive system. Though the pH of tomatoes is not that extreme and falls in the typical range of all the foods that we can consume, the acidity of tomatoes cannot be considered a problem for human health. However, excess of tomatoes can lead to excess production of gastric acid leading to acidity and heartburns. This idea is a contradiction to the eastern medicinal philosophy where tomatoes are considered to be alkalizing food when digested as it will help lower the acidity of the blood and thus create an acid-alkaline balance in the body.
How to alter the acidity/pH of tomatoes?
There can be two possibilities of altering the acidity as we can choose the tomatoes more acidic as we do it in the canning process to increase the shelf life of the product by the addition of preservatives. Therefore, in this section, we will focus on reducing the acidity of tomatoes which can be required for certain applications. In order to reduce the acidity, we have to essentially neutralize the acid by reacting it with an alkali. Therefore, a weak acid to be reacted with weak edible alkali and baking soda is the best choice for this. Cooking tomatoes with baking soda can help reduce the acidity which in turn will reduce the sour taste of tomatoes. The quantity of baking soda to be used for this purpose depends upon the number of tomatoes undergoing this process and the acidity of these tomatoes.
Conclusion
The pH range of tomatoes is between 4.1-4.6 and depends on the ripeness and cooking process of the tomatoes. pH for tomatoes is a very important parameter to check the quality of tomatoes and thus is used to be a quality control measure or test. The tomato products are acidic in nature because of the presence of citric and malic acid, however, there are ways to alter the acidity and taste of tomatoes as well. The tremendous health benefits of tomatoes have to lead to great studies in the field of biochemistry and medication.
