Food Safety – Is Unrefrigerated Kimchi Safe?

If your jars aren't in the refrigerator already, I highly recommend unscrewing the lids as soon as possible...unless you want to be able to share stories about how you found glass shards and the smell of kimchi everywhere in your kitchen one day.

Depending on when you mean to eat them, I'd recommend a mix of room temperature ripening and fridge storage. Keep the lid completely unscrewed while at room temp until ripened to a stage you prefer, and keep it loosely on in the fridge and eat it up in the next few weeks (where it will continue to ferment some more but slow down drastically). It's not a terrible idea to put something like a sheet pan under the jars just in case one overflows.

Cheesecloth is overkill, but you could choose to use that or anything that'll cover the top of a jar without making it airtight while at room temp. Glass jars are used often in commercial kimchi production and sale, so other than making sure the lid isn't fully screwed on they're fine to use. The explosion concern is mostly when you leave it too long (more than several hours?) at room temp or in the fridge for more than a couple weeks - while the jar is completely sealed.

This all depends on the kind of kimchi you are storing, of course. I'm assuming it's the freshly made napa cabbage type you're talking about. Some kimchis don't ferment as much or at all.

The clock on the danger zone starts when the food temperature drops below 60 celsius. It should be 4 hours for coffee - two hours are for meat, where it is assumed that bacteria in it have had some chance to grow while it was being butchered, transported, and stored in a supermarket. In coffee and creamer, there will be no bacteria growth at all in the ingredients, it will start after you have brewed the drink and mixed in the creamer, and the temperature has fallen below 60.

If you want to go by the book, measure the temperature of the coffee inside the thermos 5 hours after brewing. If it is above 60 Celsius, then it is still safe up to 9 hours after brewing. Do it on several days to have a significant result.

(For those of us on my side of the pond, that's 140 degrees Fahrenheit. )