Rice Vinegar (Komezu)
Japanese rice vinegar is markedly different from the harsh bite of malt vinegar or even Western white wine vinegar. It's made from fermented rice—specifically the sugars in rice are converted to alcohol, then that alcohol is fermented again into acetic acid. This double fermentation creates a much gentler, rounder acidity.
The result is delicate and slightly sweet, with an acidity of around 4-5% compared to malt vinegar's 5-8%. This means it won't overpower other ingredients or make your mouth pucker. When you eat properly seasoned sushi rice, that gentle tang comes from rice vinegar.
The most common type is plain rice vinegar (pale gold in colour), perfect for sushi rice (sushi-zu when seasoned with sugar and salt), sunomono (vinegared salads), and delicate dressings. You'll sometimes find seasoned rice vinegar (already sweetened and salted)—convenient for sushi rice but less versatile for other uses. Check the label; if it lists sugar and salt in the ingredients, it's pre-seasoned.
Some regional varieties include:
● Kurozu (Black Rice Vinegar) - Made from unpolished rice, aged for years, with a deep, mellow flavour
● Akazu (Red Rice Vinegar) - Made from sake lees, traditional for Edomae sushi
These speciality vinegars are harder to find and quite expensive, so the standard rice vinegar is perfectly adequate for home cooking.
Rice vinegar keeps almost indefinitely in the cupboard due to its acidity—the vinegar actually becomes milder and more mellow with age. Store it away from direct sunlight, and it'll be fine for at least two years, though the flavour is most vibrant within the first year.
A Quick Note on White Wine Vinegar as a Substitute
If you're caught without rice vinegar, you can approximate it by diluting white wine vinegar with water (about 3 parts vinegar to 1 part water) and adding a pinch of sugar. It's not quite the same, but it'll work in a pinch for dressings. For sushi rice, though, do get proper rice vinegar—the difference is too significant.
