Chilies are an essential spice in Thai kitchens, indispensable in dishes that are boiled, stir-fried, curried, or fried. Their spiciness is the charm that makes food flavorful and well-rounded. However, when we go to the market or open the fridge, we often see both " red chilies " and " green chilies " mixed together. Many people may wonder, besides the difference in color, how do these two chili colors differ, and which one delivers a spicier kick?
The fact that many might not know is that green chilies and red chilies (of the same variety) are actually the same chili fruit. The difference in color comes from " the harvest time " or the ripeness of the chili fruit itself.
Green chilies are unripe or not fully mature fruits. When the chili starts to grow and expand, it is green due to a high chlorophyll content. They are commonly used in dishes such as green curry, northern Thai chili paste (nam prik num), seafood, and pickles.
Red chilies are green chilies left on the plant until fully ripe. As the chili matures, chlorophyll breaks down and is replaced by red pigments such as lycopene and carotenoids, changing the chili's color from green to yellow, orange, and finally red. Red chilies are popular in dishes like red curry, tom yum soup, chili sauces, and are dried to make chili powder.
If you compare chilies of the same variety and size for spiciness, the answer is " red chilies " usually have a higher level of heat than green chilies.
This is directly related to the plant's growth science. Chili spiciness comes from a compound called capsaicin, which accumulates in the central placenta and ribs of the chili. The longer the chili remains on the plant (until it ripens red), the more capsaicin is produced and stored, protecting the fruit from being eaten before the seeds mature for reproduction.
Therefore, red chilies, having fully accumulated capsaicin, offer a deeper and more intense heat than green chilies. However, spiciness does not depend solely on color but also on the variety (for example, green bird's eye chili can be spicier than red Thai chili). But within the same variety, red chilies are always spicier.
Red chilies and green chilies each have their unique characteristics. " Green chilies " provide a fresh, vegetal spiciness and aroma, suitable for dishes that require distinctive color and fragrance, while " red chilies " deliver a more intense heat with a well-rounded flavor and vibrant color that stimulates the appetite. Choosing between them depends on the desired taste, aroma, and appearance.