Adding Fruit / Oxidation Issues?

[Mr Drinklestien]

I'm currently fermenting a 16 gallon batch with Philly Sour yeast (Stainless Conical). After day 15, I'm going to run a trub and yeast dump then add 30 lbs of tart cherries (as is). The cherries are frozen and will be thawed 32 hours in fridge prior to being added. I'll then purge and pressurize the conical with CO2. My question, with this much fruit being added, what's the chance of oxidation from adding 30 lbs of fruit, is there any way to mitigate? Will the CO2 purge be enough to remove any oxygen introduced. Background on the cherries, they are from a farm here in Ontario, they are pitted and placed into a 10 lb pail during cherry season, if not sold in "X" amount of time they are frozen at the farm in the pail. Would it be wise to add some potassium sorbate to the fruit to kill off any wild yeast, or just toss the fruit in. I'm planning to leave the beer on the cherries at 68F for three weeks before kegging.

Cheers

 

[day_trippr]

You definitely need to do something to sanitize the cherries. When I add mass quantities of frozen raspberries I heat them in a pot to 145°F and hold them there for 35 minutes to pasteurized them, then cool them to room temp before adding to the base wheat beer...

Cheers!

 

[Mr Drinklestien]

Thank you for the info!

Few questions on this,

- Will the flavour change during pasteurization?
- Would you be able to add potassium metabisulfite direct to the cherries rather that pasteurize?
- What would be the bad side / worse case scenario of adding the cherries without either pasteurizing or adding potassium metabisulfite?

Cheers

 

[day_trippr]

- I don't think there was measurable character change if any. And I'm still drinking the last batch of that raspberry hibiscus wheat beer and the raspberry character is still going strong.

- I have no experience with any metabisulfites, have to defer to someone else on that one

- fruit commonly bear wild yeasts and fungi. Worst-case you get a wild infection that isn't a good one...

Cheers!

 

[Agent]

Especially because your cherries were pitted for a period of time before freezing, yeast/bacteria may have established themselves in places where a quick wash of metabisulfite may not do an adequate job of knocking them down.

 

[Mr Drinklestien]

Noted, thank you gentlemen. I'll run with the pasteurization method as you had described.
being 30lbs of cherries, I was going to ladle them into the 4" port on the top of the conical to minimize the amount of oxygen, then close & purge with CO2. I'll be running a trub dump on Saturday followed by a yeast dump Sunday prior to adding the cherries (day 14 of fermentation @ 69F). Leaving on the cherries for 3 weeks at 64F. Any concerns you see with the current methods in regards to oxidizing?

 

[day_trippr]

fwiw, as I use carboys, when I do a fruited wheat I rack the base beer on top of the fruit in a freshly sanitized carboy - with a half cup of corn sugar added just to provoke some extra CO2-production - and do a rudimentary CO2-flush before attaching the blow-off. Oxidation has not been an issue to date...

Cheers!

 

[Mr Drinklestien]

Cherries were pasteurized between 146F-150F for 40 min. I cooled the cherries to 80F over 4 hours then popped it into the fermenter (also added 1.5 tbsp of cinnamon). I purged a few times with CO2. Next day the pressure was rising on the gauge so there's a minute amount of yeast activity, looks to be enough to drive away any oxygen that made its way in with the cherries. lol, next challenge is going to be transferring into the kegs without the tube being clogged with cherries...Well at least this is another 3 weeks away kind of problem lol

Thank you for the tips.

 

[day_trippr]

fwiw, I rack out of my carboys using an SS cane with a section of paint strainer bag material rubber-banded to the end with a large SS washer inside. The washer keeps the bag open/prevents it from being sucked into the racking cane. Sanitize the assembly before using it in a CO2-push transfer...

Cheers!

 

[Mr Drinklestien]

Well...I did a trub dump on Saturday (day 14 of fermentation) then a yeast dump on Sunday. Both didn't have as many solids compared to other trub and yeast dumps done via other types of yeast. Cherries were added on Sunday...PSI on the conical was at 5. Tuesdays PSI jumped to 12, when i purged it it quickly rose back to 12PSI, where it currently remained yesterday. Going to assume there's a lot of yeast still hanging around and eating at the sugar in the Cherries. I dropped the ambient temp to 62f which now puts the fermentor at about 59F.
I did take a reading on Sunday prior to adding the Cherries and I was at a 1.010 FG (from a 1.056 OG). I think i'm going to need to add some Maltodextrin to give a bit more perceived sweetness in order to balance out the dryness/tartness, looking at 2lbs split for the 16 gallons (added direct to kegs). I would add Lactose but by wife is lactose intolerant. Seeing as there's still yeast, I'll need to reduce the time on the cherries from 3 weeks to 2 weeks in order to get the beer off the yeast (4 weeks), there's 33 lbs of cherries and i don't think i'll manage another yeast dump due to tube clogging.