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My Tomatoes Taste Bitter Or Sour – All You Need To Know

My tomatoes taste bitter or sour – all you need to know

For anyone that takes pride in growing their own tomatoes, ending up with bitter or sour-tasting produce can be quite disheartening. In such unfortunate outcomes, it is wise to identify what would have gone wrong, to avoid making the same mistakes in the future.

Additionally, even store-bought tomatoes can also taste off. Particularly the cheap tinned varieties which are well-known for having an unpleasant “metallic” taste.

Consequently, it is ideal to have an arsenal of cooking solutions that can be used in most tomato-based dishes, to counter the taste of sour or bitter tomatoes.

What Causes Bitterness And Sourness In Tomatoes?

The flavor of tomatoes is often described as sweet, tangy, and mild. Over 400 aromatic and volatile compounds determine the taste, but the most prominent components are sugar and acid. The main sugars in tomatoes are fructose and glucose, which give a sweet flavor.

While the main acids are citric acid and malic acid, which give a tart flavor and promote salivation. When the flavor components of tomatoes are unbalanced, the most common consequences are the development of bitterness or sourness in the fruits.

These two tastes can be hard to distinguish, and they are commonly mistaken for each other. However, they occur under different conditions.

Sourness develops when foods have an acidic pH (between 0 to 7). In tomatoes, this typically occurs when they are picked too early. Bitterness, on the other hand, develops when the pH of foods is alkaline (between 7 to 14). In tomatoes, it often develops in overripe fruits.

Tomato Type

Individual palate and tomato type can be considered to contribute the most to the taste of tomatoes. Most people prefer tomatoes that have an equally balanced sweetness and tartness, but several tomato varieties are naturally quite acidic or bitter.

Interestingly, in some bitter varieties, the taste is due to the “mouth feel” of the tomato skin, more than the volatile compounds produced.

Environmental Factors

Environmental factors also contribute significantly to the development of flavors in tomatoes. Sour or bitter-tasting fruits are often produced when plants get inadequate sunlight, or they get attacked by pests and diseases. Growing tomato plants in nutrient-poor soils or excessively watering fruits also affects their taste.

Additionally, many tomato varieties have lost their sweetness over decades of intensive commercial farming. Tomatoes were originally sweet, multi-colored berries that were smaller than peas. However, selective breeding practices favored factors like higher yields, disease resistance, and firmness over taste.

This has resulted in the alteration or loss of essential flavor genes, and many varieties of tomatoes that are available today are less sweet, bland, sour, or bitter.

How To Avoid Growing Bitter Or Sour Tomatoes

The flavor of tomatoes is primarily determined by their variety and the conditions under which they are grown. These factors lead to differences in the production of sugars, acids, and other complex flavors as plants mature.

Consequently, to avoid growing bitter or sour tomatoes, the plant type must be selected wisely, and the best gardening practices must be implemented, as listed below:



Smaller sized tomatoes, like cherry and grape tomatoes, tend to have higher sugar concentrations.

They have not been exhaustively bred. So they retain unique and robust flavors, and they taste sweeter than fuller sized tomatoes.


Different pigments in tomatoes produce different balances of sugars and acids. This holds true for both hybrid and heirloom tomato varieties.

The most acidic types are red, green, purple, and black tomatoes. Red tomatoes, in particular, are characteristically very juicy and are known to have a “classic” tomato taste. Green, purple and black tomatoes have more complex atypical flavors that tend to be enjoyed by some, but disliked by others.

Orange, yellow, and pink tomatoes have medium acidity, while white and bi-colored tomatoes have the least acidity and greatest sweetness amongst tomatoes.


Tomato plants that have more leaves trap more sunlight, which is converted into sugars and other flavor compounds.

Heirloom varieties tend to produce more leaves than hybrids, and this, in part, explains why they produce intense distinctive flavors. However, no matter what type of tomatoes are planted, careful pruning can help to maintain leaf health and promote dense foliage.

Growth Conditions:

Sunlight And Temperature

To avoid growing sour tomatoes, suitable varieties must be selected based on the climate they will be grown in. Generally, tomato plants require a lot of sunlight and heat to grow well and produce flavorful fruits.

At least 8 hours of sunlight a day is necessary, together with a daytime temperature of at least 80oF, and a nighttime temperature of at least 50oF.

However, some varieties of tomatoes are tolerant of cold and cloudy conditions and can be successfully grown in cooler regions.


To grow fruits with a well-balanced flavor, tomato plants must be watered consistently before fruiting begins. Once fruits appear, watering must be done sparingly because drier and hotter conditions lead to increased flavor production and concentration.

Spacing Tomatoes

Tomato plants must be well spaced to avoid crowding, which blocks sunlight from reaching the tomatoes well. Crowded vegetables often have stunted growth, reduced fruit production, and poor sugar production. Additionally, crowding promotes pest and disease spread.

Pest And Disease Control

Stink bugs, aphids, and other pests that feed on tomatoes can damage them and ruin the taste of the fruits. Diseases like a late blight that are caused by fungal infections can also badly affect tomato taste, leading to bitterness.

Pests and diseases can be hard to control, but to avoid plant damage, some simple and non-toxic control measures can be utilized.

For instance, a spray bottle with soapy water can be used to remove or kill insects from plants. An antifungal spray can be made by making a baking soda and vegetable oil paste, that is then mixed with water and castile soap.

Soil Health

The planting soil used must be ideal for optimal tomato growth. Other than clay soil, most soil types will work well, but loam and sandy soils tend to grow the best tomatoes.

For soil that has a lot of clay, the texture can be enhanced by tilling the soil and adding modifiers like sand, sawdust, or peat moss before planting. Additionally, organic fertilizers can be used to ensure that the soil contains a lot of nutrients that can be used by the plants to produce the best flavors.

Plants Must Be Started Early

Tomatoes grow best over long, hot seasons. This provides them with ample time to produce high concentrations of sugars and other flavor compounds as they ripen. In cooler climates, seedlings can be started indoors before the last frost, to extend the growing season.


Tomatoes must only be picked when they are ripe. This is because their acidity decreases, while their sweetness intensifies as they fully ripen and mature.

If possible, they must be left to ripen on the vine, as this helps to concentrate flavors. However, if they must be picked early, they can be stored in a dry bowl or plastic bag to ripen. Unripe tomatoes must not be refrigerated, as this will have a counteractive effect, and prevent the fruits from ripening.

How To Improve The Taste Of Bitter Or Sour Tomatoes

Whether tomatoes are home-grown or store-bought, they must be tasted before being used in any dish, to identify if they have any sourness or bitterness. An off-taste can be improved using the following techniques:

Deskin And Deseed Tomatoes

The skins and seeds of tomatoes often contribute the most to the taste of bitter tomatoes. They can be tasted separately before cooking to identify if they are the source of the unpleasant taste.

If they are, the skins can be easily removed after blanching the tomatoes, and the seeds can be removed after chopping up the tomatoes. Tinned tomatoes can be strained to remove bitter-tasting seeds and fluids.

Baking Soda Or Salt

A pinch of baking soda or salt will tone down a tomato sauce that is too acidic and sour. They have more alkaline pH levels that help neutralize the acidity of the tomatoes.


Brown sugar and natural sweeteners like honey, carrots, wine, sweet pepper ad onions can be added to conceal both tomato acidity or bitterness.

Herbs And Spices

Herbs and spices can be used to offset the taste of both sourness and bitterness in dishes. Some ideal ingredients are bay leaves, garlic, and dried oregano.

It Is Not Always The Tomatoes

As highlighted in this article, many solutions can be applied to avoid growing or cooking with tomatoes that are bitter or sour. It is also important to understand that some cooking techniques can exacerbate the acidity or bitterness of tomatoes.

For instance, when spices like basil and oregano are overcooked, they become bitter, so they are best added at the end of the cooking process. Aluminum also reacts with the acid in tomatoes, creating an unpleasant flavor, so the use of aluminum pots and pans should be avoided.