Dimocarpus longan (Lum Yai), commonly known as the longan, is a tropical tree species that produces edible fruit. It is one of the better-known tropical members of the soapberry family Sapindaceae, to which the lychee and rambutan also belong. The fruit of the longan is similar to that of the lychee, but less aromatic in taste
Longan fruits are small in size, averaging 1 to 3 centimeters in diameter, and have a round to ovoid shape. The fruits are enveloped in a thin, brittle, and bark-like shell, covered in small bumps, giving the surface a pebbled, rough, and textured feel. The peel also ranges in variegated light brown, green, and yellow hues and is easily removed, revealing a translucent, white-grey flesh. The flesh is semi-firm, succulent, and aqueous, encasing a large, black, and shiny hard seed. The seed is inedible, and the flesh does not cling to the seed. Longan fruits have a faint aroma and emit a sweet, subtly tart, floral, and musky flavor, sometimes releasing gardenia and spruce nuances, depending on the variety.
Longan is an excellent source of potassium to balance fluid levels within the body and a good source of vitamin C to strengthen the immune system while reducing inflammation. The fruits also provide phosphorus and calcium to protect bones and teeth; magnesium to control nerve functioning; and other nutrients such as copper, iron, riboflavin, manganese, zinc, and niacin.
Longan fruits have a mildly sweet and floral flavor that is well suited for fresh, dried, and canned preparations. The fruit’s thin skin can be peeled, and the flesh can be consumed straight, out of hand, discarding the large center seed. Caution should be taken when biting into the fruit as the seeds can be very hard and capable of cracking or chipping teeth. Many consumers choose to lightly bite and suck the flesh from the seed to avoid accidentally biting it. Longan fruits can also be blended into smoothies, pitted and sliced into green and fruit salads, or cut and stirred into ceviche. In addition to fresh preparations, longan fruits can be simmered into savory soups such as tong sui or congee, cooked with roasted meat dishes, or combined into other sweet and sour main dishes. Longan fruits also complement desserts and can be incorporated into cookies, cheesecakes, ice cream, and pudding or poached in a simple sugar syrup. Beyond culinary dishes, longan fruits are sometimes made into tea or mixed into cocktails. Longan fruits pair well with mint, meats such as poultry, beef, and pork, seafood, other fruits including lemons, bananas, coconut, cherries, and melon, mushrooms, and dates. Whole, unpeeled Longan fruits will keep for 5 to 7 days when stored in a plastic bag in the refrigerator. The fruits can also be peeled and frozen or dried for extended use.
Longan fruits are available in the late summer through winter.