How to store an opened bottle of sake, and how long you really have

Somebody opens a bottle at dinner, pours half of it, screws the cap back on and puts the rest in the fridge door. Four days later the question is whether it is still worth pouring, and the answers online run from finish it that night to keep it for months. Much of that spread comes from people measuring different things. The Japan Sake and Shochu Makers Association, the national trade body, says there is no official expiry date on sake and that a drinker can notice the change anywhere from a week to a few months after opening. This post sorts out which bottles sit at which end of that range and where the half-empty one should go tonight.

Three of the bottles named below came free. Pacific International Liquor sent the club Hananomai Katana and Kurosawa Junmai Kimoto, and Byron Stithem of Proper Sake Co. sent The Diplomat. None of them saw this before it ran, and the June scores are the room's.

What happens once the cap comes off

Air gets in and the sake begins to oxidize. The association says this happens gradually and that the flavor does not move as fast as wine's does. SAKETIMES puts the cost plainly, saying the more oxidation occurs, the further the sake drifts from the taste its makers intended, and that the lower the temperature, the slower the drift.

Drift does not have to mean decline. Beau Timken of True Sake in San Francisco, a retailer with an obvious interest in people opening more bottles, wrote in 2015 that oxidizing sake tends to get softer, rounder, fuller and perhaps sweeter instead of heading toward vinegar, and that some bottles taste better on the second or third day. Those are one shop owner's tests and not published results, but they explain why the advice splits the way it does. Someone protecting what the brewer bottled wants the sake gone quickly, and someone who likes what the fridge does to it can wait.

Real spoilage does exist, so SAKETIMES's line that sake does not go bad needs a footnote. Sake Street describes hiochi as bacteria multiplying in finished sake, which produces a sour, yogurt-like aroma and can turn the liquid cloudy. It says spoiled sake poses no significant health risk, and that pasteurization, set at 65°C for at least ten minutes since 1971, was one of the measures that made hiochi rare. A clear sake that has gone cloudy and smells of sour yogurt belongs down the sink. On a nigori, cloudiness tells you nothing, so go by the smell.

Three kinds of bottle, three clocks

Ginjo and daiginjo get the shortest clock from the association, which says to keep them cold and drink them within a week of opening, because the fruity aroma that defines them is what goes first. That covers Hananomai Katana and Momokawa Pearl, both junmai ginjo. Timken writes that the more premium brews tend to last longer, which sounds like a contradiction. My reading is that the two are judging different things, since a ginjo can stay pleasant for weeks after the top of its aroma has gone. If you paid for the aroma, use the week.

Namazake is the fragile one. It was never heated, so the association says its koji and yeast enzymes were never deactivated and its character can change very quickly, and it asks for storage below 5°C, about 41°F. SAKETIMES adds that the yeast can go on fermenting and develop a foul smell if the bottle warms up. The FDA's target for a home refrigerator is 40°F or lower, so a fridge that is set properly already clears that bar. Retailers' figures for how long an opened nama lasts run from a few days to four weeks, and none that I read pointed to a test, so I am not passing one along. Taste it every day or two and finish it early.

Bottles can also come with instructions of their own, and those outrank any general advice. Byron told us to refrigerate The Diplomat, Proper's nama yamahai, the day it arrived and to give it air after opening before pouring. That runs against Timken's remark that you do not air sake the way you do wine, and the brewery wins that argument.

Everything else has the longest clock. That means the plainer junmai and honjozo bottles, including the kimoto from June. Timken reports opened bottles holding up in the fridge for weeks and in some of his experiments for months, while refusing to give a rule of thumb because each sake behaves differently. Kurosawa, Hatsumago, Okunomatsu and Murai Family are all in this group, and none of them is listed as a nama on the score sheet. That sheet records one night for each bottle, so it says nothing about how any of them hold up after a week. We have not tested that.

Where the bottle should go tonight

• Into the fridge with the cap on tight. The association asks for an airtight cap and a refrigerator for any open bottle.
• Standing up. Sake bottles are not corked, so the association says humidity does not matter and recommends upright storage. SAKETIMES adds that upright leaves less sake touching the air and keeps it away from the cap, which can change the flavor, especially a metal one.
• Toward the back. The FDA notes that a refrigerator door runs warmer than the shelves, and a thermometer is the best way to know what yours is doing.
• Out of the light, if a big bottle ends up outside the fridge. The association says UV rays in sunlight degrade the amino acids and vitamins in sake and that brown glass exists to block them. SAKETIMES says a pasteurized 1.8 liter bottle is better standing on a dark shelf than lying on its side in a fridge. Namazake stays cold regardless.

Two storage faults have smells worth learning, and Sake Street's guide to off-flavors names both. Hineka smells like pickled daikon radish, and the piece says it most often comes from higher storage temperatures and longer storage times. Nikko-shu, or sunlight smell, is an animal odor that forms when sake reacts with ultraviolet light, and the piece notes it still turns up in less specialized stores and overseas markets. Either one can be in the bottle before you open it. The association's estimate for an unopened bottle with proper care is up to a year, and the post on D.C. sake covers what a slow shelf can do to that.

Using the last third of a bottle

The association's own advice past the first week is to enjoy the change, and the cheapest way to learn what you like is to pour a small glass on the night you open a bottle, again on day three and again on day seven. Keep the pours at the same temperature so that the only thing moving is the sake. A pasteurized junmai is the right bottle to try this on, since it has the longest clock and costs the least to lose.

When a bottle stops being something you would pour cold, Timken's advice is to warm it before throwing it away. The post on serving temperature covers how to do that without overshooting, and Kurosawa's page gives past 100°F as the point where that bottle's sweetness and chocolate notes come forward, which is a useful place to start with any kimoto that has gone quiet in the fridge.

The ones we hear most