"Why does vinegar catch in your nose? Vinegar made in 1 day, and vinegar given 3 months"

You open the bottle to make a vinegared dish and it catches you in the nose. For most people who say they dislike vinegar, this is the thing they dislike.

Yet even among rice vinegars, the strength of that bite varies a great deal. Some you can taste straight without meeting an edge at all. Where does the difference come from?

The catch comes from acetic acid lifting off

The lead player in the sourness of vinegar is acetic acid. Acetic acid is volatile: it lifts into the air and rises into the nose. What you feel is said to be a sensation in the nose rather than sourness on the tongue.

At the same acidity, though, the bite does not always register the same way. When a vinegar is rich in components other than acetic acid - amino acids, other organic acids, sugars - those are said to cover the bite and leave it feeling gentle.

A "round" vinegar, in other words, is not a vinegar low in acid. It is a vinegar with other flavors standing around the acid. And how much of those it carries changes a great deal with the time given to fermentation.

Vinegar made in a day, and vinegar given three months

Vinegar comes about when acetic acid bacteria turn alcohol into acetic acid. There are two roads to putting those bacteria to work.

One is quick fermentation. Air is forced into the liquid in the tank so the bacteria work vigorously throughout it. It is efficient, and under the right conditions the vinegar is said to be ready in about a day. Because it produces reliably and at volume, this is the method most vinegar is made by now.

The other is static fermentation. The liquid is left undisturbed and the work is handed to a film of acetic acid bacteria that forms of its own accord on the surface. Fermenting slowly beneath that film can take months. It takes labor, and output is limited. In exchange, over that long stretch the amino acids and aromatic components from the rice remain, and the outline of the acidity is said to soften.

A junmai-su whose ingredient list reads only rice, which also states static fermentation or long aging. Look for those two marks and you are unlikely to go wrong in the search for a rounder vinegar.

Tobaya Tsubo no Su: 300 years in Wakasa, a land that fed the court

Obama in Fukui Prefecture was a miketsukuni, one of the provinces that supplied food to the imperial court from ancient times. It is also the start of the Saba Kaido, the road that carried mackerel up to Kyoto.

At this crossroads of food, the vinegar maker Tobaya Suten has made nothing but vinegar for 300 years, since around 1710. The ingredients are Koshihikari rice grown in Fukui and spring water. The vinegar is set in the earthenware jars the house has always used and left to ferment quietly for over three months, holding to static fermentation. In an age when quick-fermented vinegar is ready in a day, they go on waiting for the time inside a jar.

What comes out has little of that sharp catch and is startlingly round. It is the bottle to hand to someone who says they dislike vinegar.

How to use a round rice vinegar

• In vinegared dishes. No edge stands up even undiluted
• In sushi rice. The sweetness of the rice and the acidity settle together
• In nanban-zuke and marinades. It has savor, so you get a thickness closer to dashi
• In a dressing. Cut back the oil and the acid still does not sharpen
• Cut with water or soda and drunk. The gentler bite makes it easy to take

Vinegar is not a seasoning that only does sourness. Switch to a bottle that was given time and a vinegared dish stops being "the sour dish" and becomes a savory one.

Frequently asked questions

What causes the sharp catch of vinegar?

Mainly the acetic acid in it. Acetic acid is volatile, so you register it as something rising into the nose. At the same acidity, a vinegar carrying more amino acids, other organic acids and sugars is said to feel gentler, with less of that bite.

What is the difference between static and quick fermentation?

They put the acetic acid bacteria to work in different ways. Quick fermentation forces air into the liquid to drive the process, and the vinegar is ready in a short time. Static fermentation leaves the work to a film of acetic acid bacteria on the surface and lets it proceed quietly, which can take months. Given that time, the components of flavor are said to grow more complex.

How should I choose a rounder rice vinegar?

Reading the ingredient list is the reliable way. A vinegar made from rice alone is called junmai-su, and the more rice it uses, the more savor tends to come through. Beyond that, bottles that state a method such as static fermentation, jar brewing or long aging tend toward a rounder acidity.