Reference point
Lift the lid of a jar of sticky rice after three days of fermenting.
Do this before you read on. An entry only works when you have just smelled the thing.
Sweet, yeasty, slightly prickly in the nose, with a light sourness just forming. It evaporates quickly and spreads when the lid comes off.
This is the smell of fermentation at an early stage, when sugar has formed but alcohol is not yet high. Leave it a few more days and the alcohol rises while the sweetness falls — the same jar, a different smell every day.
It sits in the top stage, rare in a fermented family that is otherwise full of heavy smells. The reason is that the small esters and alcohols of the early stage are all very volatile.
How to smell it
Make a jar of fermented sticky rice and smell it once a day for five days, writing three words each time. It is the longest exercise in the dictionary and the only one that shows you a smell changing continuously from day to day.
Why this one is hard
Because people are used to thinking of a smell as fixed. Fermented sticky rice makes you accept that many smells are really a time slice of a process.
Don’t confuse with
This entry
Fermented sticky rice
Fermented family
Both have fruity esters. Fermented sticky rice also has ethanol, so it is sharp and cold at the tip of the nose; ripe jackfruit lacks that, and is only sweet and dense.
Scientific note
Fermented sticky rice is a two-step process running in parallel. The mould in the starter breaks starch down into sugar, then yeast ferments the sugar into ethanol and esters. Alongside this a small amount of acetic acid forms, giving the new sourness. The smell changes day by day because the two steps do not run at the same speed: the first days lean sweet, the later days lean towards alcohol.
In Vietnamese life
Fermented sticky rice is eaten at the Double Fifth festival in all three regions, made three different ways. The north leaves the grains loose, the centre rolls them into balls, the south rolls them into balls with more liquid — three slightly different smells for the same name.