Cherries in kriek: Preparing + cyanide concerns

[flussohneufer]

I've recently taken over a garden that includes a sour cherry tree, so a friend and I are planning on making a kriek.
We're aiming to do a smallish-batch of about 10L (2.5 gallons). From what I've read, 2–3kg of cherries would be good for that. We'll probably have to add the cherries quite early (like 1 month into the base lambic fermentation), then let the whole thing sit for several more months into next year.
I've not tried this before, or any fruit beer, so I've got a couple of questions. I've found conflicting information about these online so far.

1. Is it advisable to prepare the cherries in any way before adding them to the base lambic? I've seen mention of freezing, which should kill some microbes? I'm not sure I want to roast/cook/pasteurize, though, as this could affect the flavour.
2. Cyanide. It's traditional to leave the cherry pits in to achieve a nutty/almond flavour. But since they will also cause the release of cyanide, I need to be sure it won't be in dangerous quantities. Obviously commercial kriek that uses the pits appears to be safe, but I'm a bit paranoid, and have seen sites advising to pit the cherries and add almond extract. Can anyone say confidently how much cyanide would be released by about 3kg of unpitted cherries in 10L of beer over 7–8 months?

 

[skeezerpleezer]

Here is what I have done with good results:
pick the cherries when they are ready, bag them up whole without any roasting/cooking (vacuum seal if possible), then freeze them. once the beer is ready thaw them out and rack onto them. Is there some reason you have to add them so soon?

I have never messed with taking pits out and neither do any other homebrewers or commercial brewers I know. I would be more concerned about the cherry flavor degradation over a long period of time than high levels of cyanide. I would definitely not add an almond extract to a kriek either, if doing that you may as well just add a cherry extract as well.

 

[suprchunk]

I have frozen, dumped in fresh, cooked them, macerated them, almost any way you can think of except for chocolate covered (yet). Cherries are my favorite fruit to add to almost any beer, especially sours. If you are concerned about the infection; freeze it after soaking in starsan.

Cyanide? Not enough of it to matter anyway. 100g-400g (200 at Cantillon in their base Kriek - 300 for Lou Pepe, though there is no penalty in going higher) per liter will give you what most good commerical sour brewers add. If you want to kettle sour or other quick-souring, non-complex beer methods I'm not sure I can help much as those beers don't taste good to me. I'm looking at you Cascade!

Traditional, turbid-mashed, continental sours? I can help.

Don't overthink this. The pH of sours will be enough to keep most other bad things at bay, as long as you are working with clean cherries, they will be okay with minimal sanitation. Just make sure they are clean and free of any dirt or rot.

 

[sweetcell]

Here is what I have done with good results:
pick the cherries when they are ready, bag them up whole without any roasting/cooking (vacuum seal if possible), then freeze them. once the beer is ready thaw them out and rack onto them.

THIS. ferment the base beer first, then add fruit, wait a few weeks, and then bottle/keg.

two reasons to do it this way, IMO:
1) fresher fruit flavor
2) lower infection risk. fruit is covered in all sorts of microbiota and if you add them to wort along with your primary yeast you're giving the wild nasties a chance to take hold. by adding them to a fermented beer, you're giving them a really rough enviro (no sugars, alcohol, low pH, etc.) where they are much less likely to thrive. freezing the fruit also knocks down the nasties population.

as others have mentioned, cyanide isn't a concern... but adding the fruit for a few weeks at the end, instead of having it hang around for the whole time, will greatly cut down even the possibility of cyanide leeching out of the pits (which, as mentioned before, isn't really a thing to be concerned about).

 

[mashpaddled]

I would not worry about contamination unless the fruit looks terrible and you're dumping mold into the beer that will give it a lousy taste. Sour beer is already low ph and alcoholic which are two barriers to most wild yeast and bacteria. If anything, you might get some extra lactic acid bacteria and yeast adding diversity to the culture. If you want to freeze the fruit for easier and faster extraction, that's your choice.

Also would not worry about cyanide. (FWIW the pits only have the precursor to cyanide--that gets formed in your body.) If you've drank quality cherry sour beer, you've undoubtedly drank beers that had whole cherries and lived. The amount of pits you would need to consume is far more than you'll ever get out of beer extraction or be able to drink before you passed out.

You should ferment out the beer and then add the fruit for additional aging. That will allow you to control the fruit flavor so you can rack off when you're happy with it. You might find after a year the cherry flavor lost its vibrancy or became too tannic.