The tomatillo, sometimes called the Mexican husk tomato, is a fruit associated with its vibrant green color and the distinctive, papery husk that encases it. It is a staple ingredient in Mexican cuisine, particularly for traditional salsa verde. Whether this fruit turns red when it ripens is a common source of confusion. The answer depends on the specific variety of Physalis philadelphica being grown, as color change is not a universal sign of maturity.
The Standard Ripening Process
The most widely cultivated tomatillos are the green varieties, such as ‘Toma Verde.’ For these common types, ripeness is not indicated by a change in fruit color. Growers look for the fruit to fully expand within the husk, causing the papery covering to stretch taut and begin splitting open. This expansion signifies the fruit has reached its mature size and is ready for harvest.
The fruit remains a bright, firm green, sometimes developing a slightly paler or yellowish hue if left on the plant longer. Harvesting ensures the characteristic tartness and density desired for savory dishes. The husks, which start green, will dry out and turn a tan or straw color as the fruit matures. If a standard green tomatillo turns deep yellow or brown, it is generally considered overripe, leading to a softer texture and a loss of its refreshing tang.
Addressing the Red Color Question
While the familiar green tomatillo does not turn red, some varieties are genetically programmed to ripen to a red or purple color. These hues are due to variations in pigment production, particularly anthocyanins, which cause red and purple coloring in many fruits. These specialty cultivars are distinct from the common green type and are intended to be eaten when fully colored.
Varieties like ‘Purple de Milpa’ develop a deep purple skin and flesh as they mature, while others, such as ‘Queen of Malinalco,’ ripen to a true red. These color-changing tomatillos are an exception and signify that the fruit is fully mature. Confusing an overripe standard green tomatillo with a specialty red variety can lead to disappointment, as the former will be mushy and bland, while the latter has a unique, enhanced flavor profile.
Flavor and Culinary Use
The color of a tomatillo is directly linked to its flavor profile and best use in the kitchen. Standard green tomatillos are harvested at their mature-green stage because they possess high acidity and a bright, tart flavor. This sharp tang makes them ideal for traditional cooked applications like salsa verde, where the acidity cuts through the richness of other ingredients.
The less common, color-ripening varieties offer a different experience. When red, purple, or yellow tomatillos reach full maturity, their acid content decreases, and natural sugars concentrate. The resulting fruit is noticeably sweeter, less tangy, and possesses a fruitier aroma. This sweet flavor makes them better suited for fresh eating, sweet salsas, jams, preserves, or desserts, moving them away from traditional savory applications.