Value Village ／ Food & living
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A jug of cold tea in the fridge is part of every Japanese summer. Barley tea (mugicha) is the classic, and as cold brewing spreads abroad, "how long does it keep?" is asked more and more often. The answer surprises many people: mugicha spoils faster than you would expect.
| Drink | Guide (refrigerated) | Why |
|---|---|---|
| Mugicha (cold-brewed or boiled) | 1–2 days | Contains starch and sugars that feed bacteria |
| Green tea (cold-brewed) | 1 day | Catechins are antibacterial, but it must not be left at room temperature |
| Black tea, rooibos (cold-brewed) | 1–2 days | As above |
| Tap water (stored) | 2–3 days refrigerated (deteriorates once the chlorine is gone) | Tokyo Metropolitan Waterworks Bureau guidance |
[Verify] Check the figures from the Tokyo mugicha study in the published material of the Tokyo Metropolitan Institute of Public Health, and the stored-water guide in the Tokyo Metropolitan Waterworks Bureau Q&A.
Just after boiling the bacterial count is low, but bacteria get in as it cools and every time you pour. Boiled mugicha is also 1–2 days in the fridge. Let it cool down first, rather than putting it in the fridge hot.
Left in, it produces off-flavours and cloudiness, and gives bacteria a foothold. Take the bag out once the brewing time is up.
The starch in mugicha stays on the inside as a slimy film. Wash it every time with detergent and a sponge, taking off the lid, gasket and spout, then dry it. For narrow-necked bottles, a long-handled sponge is the standard tool.
Once you drink from the bottle, bacteria from your mouth get in, and if there is sugar they multiply fast. Anything you have drunk from should be finished the same day; better still, pour it into a glass.
Cloudiness, sourness, thickening or a change in smell are signs of spoilage. If in doubt, throw it out — that is the safe side.
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https://www.tmiph.metro.tokyo.lg.jp/
https://www.waterworks.metro.tokyo.lg.jp/kurashi/shitsu/
https://www.mhlw.go.jp/www1/houdou/0903/h0331-1.html
⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.
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