Value Village ／ Food & living
This answer is a draft. It stays unpublished until legal review and source verification are complete.
Yoghurt is the classic example of a food people assume "is fermented, so the date does not matter." Japanese supermarkets sell it mostly in large 400 g tubs, which raises the question of how long it lasts once opened. Here is how to handle an opened tub, what the liquid on top is, and how to judge a passed date, based on how Japanese labelling works.
| Item | Details |
|---|---|
| Storage | Refrigerate (10°C or below). Avoid the door pocket, where the temperature rises easily |
| Best-before date while sealed | Usually 2–3 weeks from manufacture. If unopened and refrigerated, it is often still fine a few days past the date (check its condition) |
| Once opened (large 400 g tubs etc.) | 2–3 days. Serve with a clean spoon; do not eat straight from the tub |
| Liquid on the surface | Whey (乳清). Contains protein and calcium. Stir it back in |
| Signs to throw it away | Too sour, bitter, pink/black/green spots (mould), a bulging lid, a smell of alcohol |
| Freezing | Possible, but the texture changes (it separates). Eating it as frozen yoghurt is one option |
[Verify] The standard for fermented milk is in the Ministerial Ordinance on Milk and Milk Products Concerning Compositional Standards; check the after-opening guideline against makers' labels and Q&A pages.
It is whey. Pouring it away loses nutrients. Stir it in or eat it as it is. Cloudy liquid with a strong sour smell is a different matter.
If unopened and refrigerated, it is often still fine a few days past the date. Judge by appearance, smell and taste. Once opened, 2–3 days regardless of the date.
Bacteria from a spoon that has touched your mouth get in and speed up spoilage. Serve a portion first.
Specific effects may only be stated on products that have been approved or notified. Within the law, ordinary yoghurt is positioned as "one of the fermented foods".
The strains differ from product to product (Lactobacillus bulgaricus, Streptococcus thermophilus, bifidobacteria, Lactobacillus gasseri, etc.). Which suits you varies from person to person; the practical approach is to choose one you can keep eating.
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https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/kenkou_iryou/shokuhin/
https://www.caa.go.jp/policies/policy/food_labeling/foods_with_function_claims/
https://www.caa.go.jp/policies/policy/food_labeling/food_sanitation/expiration_date/
⚠️ 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.
What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.
This is general information. Results vary from person to person and depend on your own conditions and surroundings.
Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.
Some ingredients need thorough cooking. Eat raw only foods that are sold for raw consumption. If you have allergies, check the ingredients.
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