Zinc dosing: Kettle or Fermenter?

[BugHunter]

The standard practice in the brewery I work at is to add a dose of zinc solution to the end of our boils as a yeast additive since we're an entirely stainless system. I recently came across information indicating that we're pretty much wasting our zinc solution and causing it to bind to our hot break and precipitate out.

Short of sending off samples from our post boil kettle and our heat exchanger output do any of you have any experience with this issue? Would it be more effective to autoclave our zinc solution to sterilize it and add it directly to our fermenter, or is this a minor issue?


Papers cited:

• Vecseri-Hegyes, B., Fodor, P., and Hoschke, A. The role of zinc in beer production. Acta Aliment. 341373-380, 2005.
• De Nicola, Raffaele, and Graeme M. Walker. "Accumulation and cellular distribution of zinc by brewing yeast." Enzyme and Microbial Technology 44.4 (2009): 210-216.[/*]

[gitchegumee]

Autoclave?

I recommend using zinc vitamin supplements. These are cheap and sterile right out of the bottle. I add in the whirlpool, but I am also aware of zinc being lost in the trub. Most of my references say that half might be lost with trub complexing in the whirlpool and that you would want about 0.1-1.5 ppm in the fermenter. Double that to 0.2-0.3ppm in the kettle/whirlpool. If you already have zinc salts, then I would not autoclave. Keep it stored clean and dry and hydrate with hot water. Bugs aren't likely to flock to zinc salts! Instead of sending any samples to an outside laboratory to confirm any exact numbers, I would keep meticulous records of your fermentations and adjust accordingly. Consistency is more important that some number guideline in a book! Good luck!

[dick murton]

I'm not sure that I have heard of using zinc vitamin supplements before but this sounds like a good idea. All the big breweries I have worked in have added the equivalent of 0.15 ppm zinc (so the addition rate as zinc sulphate or zinc chloride is considerably higher) to the clarified wort, normally cold wort in FV, but sometimes added (because they are big, and can) to hot wort on transfer to the FV. I guess if you add it to the whirlpool at the end of the stand, or perhaps even towards the end of runoff, then not much will get absorbed by the trub.

For a micro brewer, I have to say I like the idea of "vitamin" grade supplements - sounds really easily controlled.

[liammckenna]

I'm not sure that I have heard of using zinc vitamin supplements before but this sounds like a good idea. All the big breweries I have worked in have added the equivalent of 0.15 ppm zinc (so the addition rate as zinc sulphate or zinc chloride is considerably higher) to the clarified wort, normally cold wort in FV, but sometimes added (because they are big, and can) to hot wort on transfer to the FV. I guess if you add it to the whirlpool at the end of the stand, or perhaps even towards the end of runoff, then not much will get absorbed by the trub.

For a micro brewer, I have to say I like the idea of "vitamin" grade supplements - sounds really easily controlled.

Philip is spot on again.

Been buying 50 mg zinc tabs for brewing from the chemist/pharmacist for years...

Pax.

Liam

[gbrower]

We have been adding Zinc here as well. I add it to the last 15 min of my boil. I've done a few water test on the amount added verses the finial product. I add at a rate of 0.5 ppm and that puts my zinc at 0.15 in the wort before pitching yeast. It will be a little different with your system and process. I suggest getting a few water tests done to make sure you have what you want.

One note on purchasing zinc sulphate. Make sure you get food or pharma grade. Zinc is commonly found with arsenic and the fertilizer grade will have some for sure. If your batch sizes are fairly small you can get away with the pills. If you need a large quantity send me a message and I can give you my contact but he only deals in 50lbs or more. That is enough for almost a year and a half for me but it doesn't go bad.

[Azbrewdude]

We were having similar issues. The lab started comparing additions vs. kettle and whirlpool. Long story short, zinc levels were much higher when it was added to our separate whirlpool vessel.

[patbrewer]

We use Servo(essentially zinc fortified yeast hulls) when we shut off the whorl pool. All of our fermentation's have been great and we have had predictable repitches, no off flavor, no attenuation problems, quick start, etc...