The simple answer to whether the jalapeño turns red is yes; the green color signifies an immature fruit, while red marks its fully mature, vine-ripened stage. The jalapeño is a cultivar of the species Capsicum annuum, which includes common peppers like bell peppers, cayenne, and paprika. Like its relatives, the jalapeño transforms from green to a final, typically red, color if allowed to remain on the plant. This natural process signals that the fruit has reached peak biological ripeness, ready to drop and propagate its seeds.
The Science Behind Color Change
The vibrant green appearance of an immature jalapeño is due to a high concentration of chlorophyll, the same pigment responsible for photosynthesis in leaves. As the pepper matures on the vine, the internal biological processes shift from growth to ripening. This change is marked by the degradation and breakdown of the chlorophyll molecules within the fruit’s cells.
Once the green pigment fades, other compounds begin to be synthesized and revealed. The red color results from the production of carotenoids, a class of pigments that includes capsanthin. Capsanthin is a potent red-orange compound that indicates full maturity. This transformation involves the conversion of chloroplasts, the chlorophyll-containing organelles, into chromoplasts, which store these new red and yellow pigments.
Heat and Flavor Transformation
The ripening process brings about significant changes not only in color but also in the pepper’s sensory profile. Green jalapeños possess a fresh, distinctively grassy, and sometimes sharp flavor due to their immature state. When the pepper turns red, its cellular structure breaks down slightly, and its sugar content increases.
The red jalapeño gains a notably sweeter, fruitier, and more complex taste. Simultaneously, the concentration of capsaicin, the compound responsible for the pepper’s heat, often increases as the fruit matures. While a red jalapeño is generally hotter than a green one, the heat difference remains within the pepper’s typical range of 2,500 to 8,000 Scoville Heat Units (SHU). The aging process concentrates the capsaicin, pushing the fully ripe fruit toward the upper end of its Scoville rating.
Harvesting and Commercial Standards
Most jalapeños found in grocery stores are uniformly green because of commercial harvesting practices. Green jalapeños are harvested while they are physically mature but still firm, typically 60 to 70 days after planting. This early harvest ensures the peppers have a rigid texture and a much longer shelf life, which is necessary for shipping across long distances.
Allowing the peppers to remain on the vine until they turn red requires a significant increase in time, often an additional few weeks. This extended period increases the risk of damage, spoilage, and softening, making the fruit less ideal for the fresh produce market. The softer texture of a fully ripe red jalapeño also makes it more susceptible to bruising during transport.
Due to these logistical reasons, red jalapeños are typically reserved for specialized products where their softer texture and sweeter flavor are desirable. They are frequently used in the production of certain hot sauces, such as Sriracha, which relies on red chilis. Red jalapeños are also the only pepper used to make chipotles, which are smoked and dried red jalapeños.