Ají amarillo vs Guajillo
The short answer
Both are mild-to-moderate coloured chillies used as the base of a sauce, from two different continents and two different species. Aji amarillo is C. chinense, Peruvian, orange-yellow, fruity and tropical. Guajillo is C. annuum, Mexican, deep red, and tastes of green tea and berry with a tannic edge. Each identifies its cuisine on colour alone, so substituting moves the dish rather than weakening it.
Side by side
| Ají amarillo | Guajillo | |
|---|---|---|
| Botanical identity | Capsicum baccatum L. var. pendulum (Willd.) Eshbaugh | Capsicum annuum L. |
| Part used | fruit | fruit |
| Origin | The Andes and adjacent lowlands of South America. Capsicum baccatum was domesticated in the region — Bolivia and Peru are both implicated in the archaeological and genetic record — and its cultivation remains overwhelmingly South American. | Mexico, where Capsicum annuum was domesticated and where the mirasol cultivar and its dried form have been grown and traded for centuries. |
| Flavour notes | fruity, apricot, floral, moderately hot, vegetal | fruity, tart, tannic, mildly hot |
| Heat | 30000–50000 SHU (typically 40000 SHU) | 2500–5000 SHU (typically 3500 SHU) |
| Flavour | Fruity and slightly sweet with a clean, forward heat that arrives quickly and does not build the way a chinense chilli does. Deveined and blanched, as it usually is, the fruit dominates and the heat becomes a background warmth — which is what allows Peruvian recipes to use it by the cupful. | Tart and fruity — cranberry and dried berry — with a green-tea astringency behind it and only a modest heat. It is the bright, acidic note in a mole rather than the sweet or the smoky one, and its tannic quality is the thing people notice without being able to name. |
| Aroma | Distinctly fruity — apricot and yellow raisin, with a faint floral edge — over a green vegetal base. It smells more like fruit than like chilli, which surprises people meeting it for the first time. | Dried berry and green tea, with a faint tannic edge. Toasting brings out a nuttiness and can tip quickly into an acrid burnt-chilli note that cannot be recovered from. |
Which should you buy?
Ají amarillo
Paste, unless you can get fresh pods. This is one of the few entries in the catalogue where a processed form is the right default rather than a compromise: the deveining and blanching that make the paste are a heat-management technique the recipes assume has already happened, and blending fresh pods without it gives a dish several times hotter than intended. Dried mirasol is the right choice where a deeper, raisiny character is wanted.
Guajillo
Buy whole pods, and this is one of the clearer cases in the dataset. Whole guajillo keeps for a year or two, can be judged by bending it before purchase, and can be toasted and soaked — the two operations that produce the sauce it exists for. Powder can do neither, fades within months, and is milled from the pods that were too broken to sell. The exception is a dry rub, where whole pods have no place and powder is exactly right.
Full detail on ají amarillo and guajillo, including evidence grades and sources for every claim above.