dried pomelo peel

Only the peel of Citrus maxima is used here, dried and milled to a powder, in one recipe: the Japanese curry powder, at 1.5 grams of dried, ground peel, three quarters of a teaspoon, in a blend that yields 44 grams. It is one of three powders, with turmeric and ground ginger, stirred in after the toasted whole spices have cooled and been ground fine. The recipe is firm about it: these three never go in the pan, because they scorch in seconds and a scorched blend cannot be rescued.

The recipe says the peel does the job chinpi does in a Japanese blend, and no masala asks for it. The compound traced to it is naringin, the flavanone that makes pomelo and grapefruit peel bitter rather than merely sour, enough at that amount to set a dry edge under the sweetness. Three tablespoons of the finished powder make one pot of curry, stirred into the roux off the heat. Sealed in a jar away from light and heat, the blend keeps about 2 months before it starts to flatten.

The Journal's note on citrus ancestry puts the pummelo at the root. Cultivated pummelos are selections from a single progenitor species, C. maxima, so a pummelo is close to a species rather than a blend, where cultivated mandarins are wild mandarin with pummelo bred in. That pummelo admixture correlates with fruit size and acidity in mandarins. Grapefruit is a pummelo crossed with a sweet orange, and sour orange is a first-generation cross of pure C. maxima and pure C. reticulata. Pummelo peel oil varies widely, from 46 to 54 per cent limonene in some cultivars to 81 to 96 in others, where grapefruit's runs 86 to 98 per cent.