Exotic fruit of Southeast Asia.
The rambutan, Nephelium lappaceum, is a fruit considered exotic to people outside of its native range. To people of Malaysia, Thailand, the Phillippines, Vietnam, Borneo, and other countries of this region, the rambutan is a relatively common fruit the same way an apple is common to many people in cooler climates. This may change for the rambutan over time as availability and distribution improve.
This web site aims to familiarize the public with the qualities that make the rambutan such a wonderful, delicious and nutritious fruit. The word "rambut" in the fruit name 'rambutan' is Malay for 'hairy,' and this refers to the spiky rind. Indeed, without the soft spines on the rind, the rambutan would resemble the lychee (or litchee) which is in the same botanical family. The structure internally is quite similar, with a single central inedible seed and edible white flesh wrapped around it but the skin is the part that makes the rambutan so distinctive in appearance. Other members of the same botanical family, the Sapindaceae, include the longan (Dimocarpus longan), the canepa or mamoncillo (Melicoccus bijugatus), the pulasan (Nephelium mutabile), and guaraná (Paullinia cupana).
How to open and enjoy
The grafted varieties tend to have larger fruit and there may be as few as 9 or 10 to the pound or as many as 16 to 18 per pound. The ungrafted seedlings tend to have smaller fruit and there may be 16 to over 20 per pound. In addition, the edible proportion inside each rambutan fruit may be reduced in the seedling due to typically smaller outside diameters combined with medium to large seeds. The other factor which may affect your enjoyment is that many seedlings have fruit with a very fibrous texture a lot like the canepa (Meliccocus bijugatus) and are quite firmly attached to the seed.
The photo below shows, on the left, the grafted rambutan fruit and on the right, a bunch of seedling fruit. The differences are striking, both in appearance and in flavor. The texture and frequently sugar content are often superior in grafted or selected cultivars. This was, after all, why they were 'selected' for mass production in the first place.
In the left photo below, the grafted variety is in the upper row, the seedling in the lower. In the photo below on the right, the upper two rows are the grafted variety and the fruits below that are from a seedling. Notice the large seed size in the cut open seedling fruit reducing the amount of the edible portion.
As you can see above, the thin-skinned rambutan fruit is quite accessible
and the edible portion makes up a large part of the whole. After making a
shallow cut through the skin and only part of the way around the exterior, the
edible white portion is exposed with some light pressure on the rind along the
line of the cut. Resembling a boiled egg about 2" to 3" long once it is removed from the rind, the rambutan fruit
easily slips out of the soft spiny skin (pericarp) and in some varieties also
slips easily (freestone) away from the pit. There are many varieties where the
edible portion is harder to peel away from the seed (clingstone) but the flavor
of the fruit is deemed more important than this quality and many clingstone
varieties have a great taste. There are also the occasional fruits where the
seed has partially withered ("chicken tongue" seed) or not formed at all,
leaving you with a delicious seedless fruit, but those are the exceptions.
When to pick
or when to buy
Notice how the fruit forms in clusters and some of these can be quite large, numbering in the dozens. As full ripeness approaches, the entire branch can sag under the weight and be pulled down a few feet. Harvesting involves cutting off the entire cluster if the majority of the fruit are ripe; if not, then several visits to the tree are required to complete the task.
From flowering to ripe fruit, it takes 90 days or more. The green fruits
start to turn
yellow and then red, sometimes quite rapidly. In some years, the process from
green to red can take place in 5 to 10 days. Keep in mind that the ripe rambutan
red but there are some varieties that finish with a bright yellow color and some
that end up with an orange blush. The flavor is pretty much the same as the red
ones. The best fruit have little or no black forming on the tips of the soft
These pictures make it possible to see the detail of the skin of a rambutan. The soft spines, or spinterns, are safe to handle and lose a lot of water after the fruit has been picked. For this reason, to hold them for any length of time in refrigeration requires some sort of plastic film to slow down the moisture loss. The spinterns may turn black within days after harvest but the fruit inside remains quite fresh and tasty for several days or a week longer. If the humidity is high, then the fruit can be held at room temperature in a plastic bag that is not sealed but rather loosely closed.