Tomato flavor is a balance of acid and sugar recognized by the tongue and the effect of volatile compounds within the fruit that cause aroma recognized by the nose. Simply put, the human perception of tomato flavor involves the integration of taste and smell.
Tomato flavor is commonly described as sweet, tart, tangy or balanced. Tomato flavor is sometimes also described as “classic tomato flavor” or “old-fashioned tomato flavor.” And the flavor of some tomatoes is described as mild or bland.
Sugars in the tomato—mainly fructose and glucose—result in a sweet flavor. Acids in a tomato—mainly citric and malic acids—result in a tart, sometimes sour flavor.
Volatile compounds or oils in the fruit which are released as fragrance when the fruit is crushed during eating contribute to flavor. Aroma is integrated with taste to create full flavor. There are 15 to 20 assertive volatile compounds in a tomato. (One tomato can have more than 400 volatile compounds.)
The amount of sugars, acids, and volatile compounds in a tomato can vary by variety and are mostly genetically determined. However, environmental factors—the amount of sunlight, nutrients, and water a plant receives as fruit develops—can affect fruit sugar concentrations and the development of volatile substances
Often tomatoes are classed as sweet flavored, acidic or sour flavored, or balanced. A tomato high in sugars and low in acids has a sweet taste. A tomato low in sugars and acids has a bland taste. Traditional tomato flavor—preferred by most people—is a nearly 50-50 combination of sugars and acids; this is often referred to as “old-fashioned” tomato flavor.
Tomatoes described as sweet contain high sugar but low acid content. Tomatoes that are high in acid and low in sugar are described as tart or tangy. Tomatoes with low sugar and low acid levels are often described as bland or mild.
The fragrance of volatile compounds or oils in fruit cells—while neither sugars nor acids (they include amino acids, fatty acids, and carotenoids–pigments)—contribute to the perception of sweetness independent of sugar concentrations. (Volatiles are sniffed through the nose as we chew food—they enter the nasal cavity from the back of the mouth. Volatile signals sent from the back of the mouth interact with taste signals sent by the tongue in various parts of the brain to create flavor.)
Texture or “mouthfeel” can affect tomato flavor. Heirloom vining tomatoes often have a pulpy texture that is associated with old-fashioned flavor. Greenhouse and determinate tomatoes—often with fewer days to maturity and thus fewer days of exposure to sun and thus the development of sugars—are firm. When texture detracts from flavor, a tomato is often referred to as mealy.
Flavor, we might say, is in the chemistry of the fruit.
Here are adjectives used to describe tomato flavor:
- Sweet: sweet, fruity, tropical, sugary, low-acid, refreshing.
- Sour: tart, tangy, acidic, old-fashioned, tomatoey, assertive, bold, citrus.
- Savory—not sweet or sour (called Umami in Japanese): earthy, rich, complex, meaty, salty, spicy.
- Balanced: balanced, complex, excellent, exceptional, intense, delicious, outstanding, flavorful.
A tomato with high sugar content and high acid content that is rich in volatile compounds is referred to as balanced, rich, and complex.
A tomato with both high sugar and high acid content is referred to as both sweet and tart.
A tomato with high sugar content but low acid is referred to as bland.
A tomato with low sugar content and high acid content is called tart. A tomato with low sugar and low acid content is called tasteless.
Here is how tomatoes can be commonly grouped for flavor by color (As noted above carotenoids or plant pigments responsible for bright yellow, red, and orange hues in tomatoes produce different balances of sugars and acids.):
- Red and pink tomatoes commonly have higher sugar than acid concentrations.
- Orange, yellow, and white tomatoes are less acidic than red tomatoes and so are mild tasting or the combination of sugar and acid levels and volatile compounds have the effect of a milder flavor.
- Black and purple tomatoes—created by a mix of green and red pigments—are known for their complex flavor—though the acid and sugar levels may be nearly balanced.
- Cherry and grape tomatoes—which can vary in color–have high sugar concentrations and taste sweeter than full-size tomatoes.
Here are favorite heirloom tomatoes and their flavor descriptors (note the color of each after the variety name):
- Arkansas Traveler (pink): rich balance of sweet and tart.
- Aunt Ruby’s Green (green): acidity with well-balanced sugar.
- Aussie (red): old-fashioned, robust flavor.
- Big Rainbow (red-orange-green striped): sweet flavor, meaty.
- Brandywine (pink): sweet with notable acidity, old-fashioned.
- Black from Tula (black-purple): sweet, complex flavor.
- Black Krim (black-purple): intense flavor, slightly salty taste.
- Black Prince (black-purple): rich, fruity flavor.
- Carbon (black-purple): exceptionally rich and sweet flavor.
- Carmello (red): “perfect” acid-sugar balance.
- Caspian Pink (pink): sweet tomato with notable acidity.
- Cherokee Purple (dark pink to blackish): complex smoky flavor with slightly sweet aftertaste.
- Costoluto Genovese (red): old-fashioned flavor, meaty, tart.
- Dona (red): smaller version of Carmello, balanced acid-sugar flavor.
- Druzba (red): robust sweet-tart flavor, meaty.
- German Johnson (red): deep, acidic tomato flavor.
- German Pink (pink): full, sweet flavor, floral.
- Gold Medal (marbled yellow-red-green): sweet flavor.
- Great White (yellow-white): mild flavor, low acidity, light sweetness.
- Green Zebra (green): mild flavor, low acidity, some sweetness.
- Japanese Black Trifele (black-purple): deep, chocolatey smoky, rich flavor.
- Juane Flamme (orange): sweet, low-acid, tropical flavor.
- Kellogg’s Breakfast (orange): sweet flavor, meaty.
- Limmony (yellow): zesty, citrusy flavor.
- Matt’s Wild Cherry (red): sweet, full flavor.
- Mortgage Lifter (pink): mild sweet flavor and meaty texture.
- Moskvich (red): rich flavor.
- Paul Robeson (black-purple): complex, smoky flavor.
- Persimmon (orange): sweet flavor, meaty.
- Pineapple (orange-red striped): very sweet, low acidity.
- Pruden’s Purple (pink): sweet, juicy, meaty.
- Purple Calabash (black-purple): rich, full old-fashioned flavor blending sweet and acid.
- Purple Russian (black-purple): meaty, sweet flavor.
- Striped German (yellow-red-green striped): sweet flavor, soft texture.
- Stupice (red): rich, tangy flavor.
- Thessaloniki (red): earthy, classic flavor, meaty.
- Vorlon (black-purple): cross between Prudens Purple and Cherokee Purple, meaty, rich, sweet flavor.
- Yellow Pear (yellow): very sweet.