The Complete Handbook of Longan

Chapter 1: Understanding Longan

Longan (Dimocarpus longan Lour.) is a medium-sized evergreen tree in the soapberry family, Sapindaceae, which makes it a close botanical relative of the lychee (Litchi chinensis) and the rambutan (Nephelium lappaceum). The part that is eaten is not the fruit in the botanical sense of a ripened ovary, but the aril—a fleshy, translucent outgrowth that envelops the seed. Commercially, the term "longan" refers to this aril, the outer skin, and the fruit as a whole unit. Understanding this structural distinction is the first step in handling the product correctly for market.

The commercial fruit is a drupe-like berry, roughly 2 to 3.5 cm in diameter, with a thin, brittle, leathery pericarp (the skin) that ranges in color from a dull tan to a light russet brown. The skin is relatively smooth and not as spiky or bumpy as a lychee's. Beneath the skin is the edible aril, which is white to translucent, and is characterized by a firm, crisp texture and a sweet, musky flavor. The aril typically surrounds one central, dark-brown to black seed, which is inedible and contains a significant proportion of the fruit's overall weight. There is a clear economic relationship here: a larger amount of aril relative to the seed is a primary marker of fruit quality. This ratio, often expressed as a percentage of aril weight to total fruit weight, is typically around 60 to 70% for good commercial cultivars, and it's a metric any buyer should be prepared to measure