Is Acid a problem for fermentation?

We have all heard that we need to use juice with no preservatives, and that Ascorbic acid is about the only additive that is OK.

I have seen juice with Citric acid and Fumaric acid. Do these inhibit fermentation, or are these OK too?

I've not looked up citric acid, but did do some searches for Fumaric acid. It seems that it is used to inhibit malo-lactic fermentation in wine, but i could not find out if it is added before or after the main fermentation.

Citric acid is vitamin C.

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mediaman said:

Citric acid is vitamin C.

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No, it isn't.

Ascorbic acid is vitamin C.



The answer with regards to fermentation is that it depends on the pH of the wort. The pH of the wort is naturally acidic already, and has some capacity for buffering to maintain a good pH for fermentation. However I read some article(s) somewhere saying that getting outside of the range of (I believe) 5.2-5.5 can cause some off flavors because the yeast do not reproduce in the same way anymore. There is probably a whole chapter about wort pH in Yeast but I haven't gotten to that part yet.

With regards to Fumaric acid specifically, I do not know if that causes issues or not.

I'm sure someone here will come in with more and or better information at some point.

Citric acid is fine it's added to wines for taste/body.

Citric acid can lead to off flavours and should be avoided for cider. When lactic acid bacteria are in the presence of citric acid they can produce acetic acid. Citric is generally avoided for cider but could be used if you don't have an alternative.