I am looking at the Saveur magazine annual 100 issue.

There are a couple of items related to fermentation; and I am intrigued.

The recipes instruct to let the mixtures to stand at room temperature for around 5 days.

Is there a proper "room temperature" for that to work ? or is it a trial by error kind of thing ?



2 Answers 2


The proper temperature is the average temperature range of the type of room in which the fermentation was historically done by the culture which invented the specific fermentation dish.

I know this is not what a modern cook wants to hear, but there is no easier way to put it. Recipes were invented to work at a certain temperature, and because this was such a ubiquitous part of the whole thing, and historically so hard to change, that it does not appear in the recipe itself.

For example, if you are creating a sourdough starter, you can easily stay around 20 Celsius. The range is rather wide, but the exact smell of the starter will depend on the temperature you had, as you're likely to get slightly different bacteria at 25 Celsius than at 18 Celsius.

Other recipes will need another temperature. You seem to need well above 30 Celsius for dosa batter to ferment properly. Other cases, such as sauerkraut or wine, need a temperature more common in old European cellars, between 10 and 15 Celsius. Salami might fare best if you have a bit less than that. Yogurt needs to be quite warm, but depending on the temperature you choose within the "warm" range, you will get sharp vinegary bacteria or milder lactic bacteria. And so on.

If you have a modernized recipe which directs you to use room temperature, stay in the 20-25 Celsius range. But if you are not sure the recipe has been made with climatized rooms in mind, you might need to do some research.

  • +1 - I would just add that historical temperature ranges often were quite wide, since rooms were rarely at stable temperatures without modern heating/cooling systems. We can target the range better nowadays, and many microorganisms have been selected for specific ranges (e.g., modern commercial yogurt cultures tend to work best at a higher temperature than what would probably have been used historically).
    – Athanasius
    Feb 21, 2016 at 3:19

Trial by error. Sandor Katz in "The Art of Fermentation" indicates tropical "room" temperatures may run a fermentation to completion in just half a day, while more pole-trending latitudes could instead require multiple days. Also of concern may be mold, especially for a five day ferment without rotation and feeding of the input, though that will vary by location, what is being fermented, whether the container used is somewhat open or a rubber gasket jar, etc. The desired duration will also depend on how sour one wants the resulting product, etc.

Temperature while important by no means covers the whole story--what container is best used?--what adjustments must one make if that container is not available, or is unsuitable?--how to deal with mold?--what happens when the inputs have regional differences unaccounted for by the recipe?--which inputs are best to use?--how sour should the resulting dish be?

Trial by error has been an essential tactic for maintaining a sourdough colony (modern flour is terrible, need whole grains), Moroccan preserved lemons (boy howdy mold problems but think I have a good fix for that), beet kvaas (duration is critial, as left too long hey there's that Seattle mold), kraut, mead, etc.

  • This is true. While living in Florida, I made a beer out in the garage which was around 80degF. I itched the yeast and checked on it the next day. No activity at all. I pitched more yeast and checked it later the same day. Nothing. Flummoxed I took a gravity reading and lo...the whole fermentation has started and finished overnight. Wow!
    – Escoce
    Feb 18, 2016 at 19:03
  • I disagree that it's "trial by error." It may have been in the past, but not with modern scientific studies of fermentation under controlled conditions. As rumtscho's answer points out, there are standard temperatures that tend to work for different types of fermentations. And while these may work over a wide temperature range with varying results, most of the results are somewhat predictable when you change the temperature.
    – Athanasius
    Feb 21, 2016 at 3:13
  • @Athanasius we'll agree to disagree, then.
    – thrig
    Feb 22, 2016 at 15:36
  • I appreciate your edits, but the reality is that there have been scientific studies done on most of the issues you mention, and there are clear methods that produce consistent results (maintain adequate pH range, produce sustained colonies, inhibit mold, etc). If it were just "trial by error," large-scale commercial fermentation would be impossible (but it obviously is possible). Just because most home do-it-yourself fermentation is imprecise doesn't mean that it can't be precise.
    – Athanasius
    Feb 22, 2016 at 22:09
  • @Athanasius "impossible, but obviously is possible"? Which is it? Fermentation precedes the Science of Bacon by centuries, and the Romans and Chinese were quite commercially minded, and operated empires at scale, much as is done today. And anyone who lacks the arbitrary resource use and energy burn to create certain conditions for very particular inputs must use trial by error. By the numbers, this is nearly eveyone on the planet.
    – thrig
    Feb 24, 2016 at 17:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.