Reference point
Snap a sour star fruit in two and smell the break at once.
Do this before you read on. An entry only works when you have just smelled the thing.
Green, thin, sour very quickly and with almost no aftertaste. It arrives and leaves within seconds.
This is one of the thinnest smells in the whole dictionary. There is no lining underneath — no sweetness, no flowers, no earth. Just a sheet of green and sour, then nothing.
That very emptiness makes it useful: it is the reference for “pure sour”, against which every other sour smell is thicker.
How to smell it
Snap it rather than cut it — a knife bruises the tissue and adds a metallic smell. Bring the break close to your nose within the first three seconds. Any slower and most of it has gone.
Why this one is hard
Because it is so thin that beginners conclude star fruit has no smell. It does; it is simply so faint and so short-lived that you have to go after it to catch it.
Don’t confuse with
This entry
Sour star fruit
Citrus family
Star fruit is thin and empty — nothing under the sourness. Ambarella has a clear resinous note, strongest in the tissue around the stone.
Scientific note
The strong sourness of star fruit comes from oxalic acid, which does not evaporate and so contributes nothing to the smell. The smell comes from six-carbon aldehydes and alcohols — the same group of green-leaf compounds found in freshly cut grass. That is why star fruit reads as “green” rather than “fruity”.
In Vietnamese life
Sour star fruit goes into sour soup, braised fish, or is eaten with chilli salt. The star fruit tree in the yard is a familiar image in Vietnamese literature and folk verse, and the star shape of a sliced fruit is one of the few plant images that has entered everyday language.