I am planning to brew sahti, which is supposed to have clove (phenolic) and banana (esters) flavors. They are said to be possible to make with baker's yeast, which I believe is possible for the moment.

My question is whether I should make a ferulic break during mashing to enhance phenols from rye malt (which is about 30% of fermentables) or is this technique only viable with wheat malts? In other words: does rye malt can be source of ferulic acid and if yes, is the ferulic break temperature the same as for wheat?



Ferluic Acid Rest

This rest is one that people who make wheat beers sometimes use. It is short but its at 111-115 degrees. It develops ferulic acid. Doing this rest aids to the clove like flavors that are in wheat beers..

Yeast: The Practical Guide to Beer Fermentation

"Performing a Ferulic asic rest around 110F(43C) can increase the level of ferulic acid in wort, which some yeast strains convert to 4-vinyl guaiacol."

as for Rye, it does contain feluric acid. How much it contains it dependent on variety of rye (source), also you are going to need a yeast that can convert Ferulic acid to 4-vinyl for that clove aroma.

In my opinion a Ferulic Acid rest may benefit clove aromas, but you may need to do a side by side test to verify.

  • Thanks for your research. In the meantime, I have decided to do just one temperature mashing for purely laziness related reasons (as it is going to be rather thick mash), but I will keep it in mind.
    – slawekwin
    Sep 23 '16 at 6:16

It's my understanding that ferulic acid is released in the mash and produced by yeast in fermentation.

Typically unmalted rye is used in sahti this may have similar properties as malted wheat concerning ferulic acid giving you the clove ester. But clove can be obtained easier by yeast esters.

The sahti style has no boil and a starting ABV of 7%. While bakers yeast is the traditional I'm not aware of any that have a tolerance above about 5% that's readily available. So because of the lack of a boil to sanitize and the high starting ABV, I would strongly recommend Wiezen yeast with a pretty good pitch so it dominates quickly in a warm fermentation. This will give you the esters your looking for. Typically a wiezen for phenolic will be underpitched, in a sahti I would at least do a standard starter for the volume of wort / OG, and rely on the warm temp for a very fast growth phase to produce the esters.

  • Clove phenols are actually produced during fermentation (by yeast) from ferulic acid (among others, of course). I am not asking about esters here, though - this is entirely different from phenols. I am planning to boil for about 20 minutes, so wild microbes are not unusual concern here. As for yeast alcohol tolerance I will have to give it some more thought, thanks.
    – slawekwin
    Sep 21 '16 at 14:57
  • From what I read, baker's yeast can survive in up to 14-15% ABV...
    – slawekwin
    Sep 21 '16 at 16:28
  • @slawekwin I've done a lot of ciders and Applewine with bakers yeast even with nutrients in my experience they die out at 5% ABV. There are many strains, I'm sure can get high ABV. But I've not been able to get what's available to me past 5%. Sep 21 '16 at 19:29

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