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Corrections from Tariq Ahmed:
Hey Dan,
Was just reading the cider page and noticed a couple mistakes. You had sent me a link to edit a while back but I can’t seem to find it so I thought I’d just let you know.
1. Under the Malolactic Fermentation section, it says MLF decreases pH. That’s incorrect, MLF increases pH (decreases acidity).
2. Under Spontaneous Fermentation, there is this note:
“The other major issue faced by cold fermented ciders is sulfur production. Due to the colder temperatures, the sulfur will off gas less, again requiring warming of the cider to encourage off gassing. If the cider tastes good otherwise, further fermentation can be halted with the use of sulfites. Adding more sulfur containing compounds to already sulfurous cider may not be the best decision, however, so you would have to balance the potential flavour contribution with the stability of the cider.”
So, there’s a bit of confusion here because the same generic ‘sulphur’ term is being used to describe two very different things.
The ‘sulphur’ aroma being produced during fermentation is hydrogen sulfide (H2S). This compound is also commonly produced by saison yeast strains. It is produced during fermentation because yeast are liberating sulphur from sulphur containing amino acids, as they use them for nutrition in lieu of easier to use amino acids.
Sulphites (SO2) are a completely different compound used for stabilization and protection against oxygen. SO2 actually helps reduce H2S so saying this:
‘Adding more sulfur containing compounds to already sulfurous cider may not be the best decision, however, so you would have to balance the potential flavour contribution with the stability of the cider.’
Is wrong.
Sulphiting (AKA adding SO2) eliminates H2S by the following reaction:
2H2S + H2SO3 → 3S + 3H2O
(Adding sulphites in aqueous solution is H2SO3).
thanks, I will make the corrections and cite you as the reference!
No problem! Sulphur compounds in wine/cider and yeast metabolism in general are actually a little more complicated than what I wrote above. Here’s a good link: https://brocku.ca/ccovi/wp-content/uploads/sites/125/Karl-Kaiser-Controlling-reductive-red-wine-aroma-2010-.pdf
brocku.ca
brocku.ca
Brock teaches wine and cider making courses here in Ontario
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