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Help with Zinc as yeast nutrient

Discussion in 'Homebrewing' started by far333, Dec 30, 2012.

  1. far333

    far333 Advocate (640) Connecticut Nov 16, 2002

    I bought zinc pills recently in the hopes of using them as yeast nutrient. I ground them up in a coffee grinder to make a fine powder. Now I'm trying to determine how to actually add it.

    On page 75 of White/Zainasheff's "Yeast" book, they suggest adding .2 to .3mg/L near the end of the boil for enough nurtrient in the fermentor. Therefore, in a 6 gallon boil, roughly 23 L, I would need 7 mg of zinc, or .000246918 ounces. How does one measure out such a miniscule amount without a digital scientific scale? Thought I read on some website where someone suggested a specific dilution of zinc powder in water, where a few tablespoons of the solution equated to the right amount of zinc.

    Also, White and Zainasheff reference zinc chloride or zinc sulfate. My pill jar lists zinc gluconate as the main ingredient, with several other filler ingredients such as cellulose, dicalcium phosphate, stearic acid, croscarmellose sodium, glycol, and magnesium stearate. Will this zinc be appropriate?
  2. Reminds me of when Theakston's Brewery replaced their brass fittings with stainless steel and found the yeast went on strike! It had become accustomed to zinc leached from the brass.The brewer added 50 ml of zinc chloride solution to each brew and everybody lived happily ever after.
    50 ml in a full commercial brew isn't a lot. Suggest just a few drops might be enough for a homebrew quantity.
  3. Ilanko

    Ilanko Aficionado (190) New York Aug 3, 2012

    I love to figuration simple homemade solution, but this wyeast nutrient is so cheep and simple to use. 1/2 tsp per 5 gallon, dissolve in water and add it at the last 10 min.
  4. I would guess you find out what each pill weighs and how much zinc is in each, and divide the pill up visually accordingly. This should work provided your pills aren't 50 mg+ per pill.
  5. VikeMan

    VikeMan Advocate (740) Pennsylvania Jul 12, 2009

    IIRC, I think hopfenunmaltz adds zinc to his batches. Hopefully he'll weigh in.

    I get my zinc from Wyeast Nutrient Blend.
    DubbelMan likes this.
  6. far333

    far333 Advocate (640) Connecticut Nov 16, 2002

    I've already ground the pills into a powder
  7. far333

    far333 Advocate (640) Connecticut Nov 16, 2002

    Just a few drops is probably way too much. White/Zainasheff call for .000246918 ounces in 6 gallons. Overdoing it can cause flavor problems.
  8. BobCS

    BobCS Aficionado (205) New York Sep 15, 2006

    The pill will also have inert materials so you still need to know what the dose of zinc in each pill is. You can't just weight out 0.0002 ounces of the ground powder. Typical supplements might contain 50 mg zinc per tablet. Using that as an example, if you want 7 mg in your batch you'd use 7/50th of a pill. That is still a small fraction, but if you can estimate 1/10th of a pill you'd be at least close.
  9. Or if you know how many pills you already ground up, you make 7 (or 14, 21, etc...) approximately equal piles or dust...
  10. cmac1705

    cmac1705 Aficionado (245) Florida Apr 30, 2010

    You could also do serial dilutions to get a concentration that's amenable to measuring in ounces. Of course, you would still need to know the exact mass of zinc. And some graduated cylinders wouldn't hurt either.

    Or you could eyeball it.
    mountsnow1010 and inchrisin like this.
  11. I use 15 mg diet suppliments. Half per 10 gallons, grind it after I split it.

    7.5 grams/38 liters = 0.197 grams/liter which is close enough.
  12. mountsnow1010

    mountsnow1010 Savant (360) Vermont Jan 23, 2009

    This would be the easiest way to go about it without a scale that can measure 7 mg (and even that is a pain in the ass and I avoid it in the lab if I can).

    The supplement should tell you how much zinc, by weight, is in each pill. I will assume it is 200 mg as an example. Weigh the pill, and it should be more than the weight of zinc per pill (because it has the added weight of the fillers, binders etc). For my example I will assume it is 400 mg. You can then determine (approximately) that if you weighed out 1000 mg of pills (or 2.5 pills), you would have 500 mg of zinc. You can then dissolve it in a known amount of water (I would use distilled or purer, but that's just me being anal, probably not necessary for your purposes). Let's say you dissolved it in 1000 mL (1L). You would have a 0.5 mg/mL solution of zinc. So if you need to add 7 mg of zinc, you can just add 14 mL of your solution. It's late and I have had a few beers but I think my math is correct.

    Finally, this is assuming that the 200 mg of zinc is just 200 mg of zinc. If it's 200 mg of zinc gluconate then you will have to account for the weight of the anion component of the salt (gluconate in this case).
  13. pweis909

    pweis909 Advocate (705) Wisconsin Aug 13, 2005

    Dissolve some larger amount into a known amount of water, and then add a solution to your beer in measured amounts of liquid that contain the desired amount of zinc.
  14. far333

    far333 Advocate (640) Connecticut Nov 16, 2002

    This was very helpful. I can't do this by the pill since I've ground up all the pills, but I weighed the entire amount of powder, and it's 50 grams by weight. The amount of zinc per pill was 50mg, and there were 100 pills, so I've got 5000mg of zinc in my 50g of powder, or 100mg of zinc per gram of powder. The smallest amount of powder that I can reasonably weigh out on my scale is 5 grams of powder containing 500mg of zinc. I can dilute this in 500ml of distilled water and store in a half liter plastic soda bottle, and I'll end up with a solution of 500mg of zinc per 500ml, or 1mg/ml. I can then measure out roughly 7mg of zinc for my six gallon batch by measuring out 1.5 teaspoons of the solution, which is 7.5 ml.
    mountsnow1010 likes this.
  15. VikeMan

    VikeMan Advocate (740) Pennsylvania Jul 12, 2009

    I'm pretty sure (but not 100% sure) that when a supplement label says something like...

    "Zinc (as Zinc Gluconate) 50 mg"

    ...that 50 mg is the elemental zinc content, and not the Zinc Gluconate content. It's confusing (to me anyway), because it's a different convention than, say, the 'Sulfate as Sulfur' (Sulfate, SO4-S) from a water lab report, where the 'as' means the weight of the 'as' substance.
    mountsnow1010 likes this.
  16. far333

    far333 Advocate (640) Connecticut Nov 16, 2002

    I believe you are correct VikeMan. The front of the pill jar says 50mg, and the nutritional info on the side of the jar lists the serving size as one caplet, and lists zinc content as 50mg per serving, without a distinction for zinc gluconate.
    mountsnow1010 likes this.
  17. Wow, sure glad I just buy Wyeast Nutrient!
  18. mountsnow1010

    mountsnow1010 Savant (360) Vermont Jan 23, 2009


    Thanks for the clarification. I am more familiar with drug labeling than supplement labeling, but looking at my package of multivitamins, I would agree one hundred percent!
  19. billandsuz

    billandsuz Savant (380) New York Sep 1, 2004

    why does your wort need zinc? is there a zinc defficiency?

    i am with the others on this one. a careful and controlled addition of yeast nutrient is probably all you need, and even then only for big beers or if the yeast is stressed or otherwise not optimal.

    great has been made forever without having to measure zinc additions. i am not suggesting that you don't follow your path. its homebrewing and we all love to make it more complicated, only that there is a better way.
    Cheers.
  20. Wort is deficient in zinc and the yeast need trace amounts of zinc. This is pretty well known. Many breweries make sure there is zinc added to the wort, or built into the yeast when propagating. I have been at enough talks at the NHC where the yeast experts talk about making sure the yeast get the trace amounts of zinc, so I do it.

    Edit: In addition to the reference to Yeast above, here is another one.
    http://www.howtobrew.com/section1/chapter6-9-1.html
    far333 likes this.
  21. far333

    far333 Advocate (640) Connecticut Nov 16, 2002

    I'm only interested in zinc, and I'm a bit of a DIYer, and I seem to sometimes take the more complicated route. :)
  22. It's a mighty fine balance that can weigh stuff out to six significant figures.Particularly as the zinc content in the source material is probably only assayed to 2 or 3.

    Agreed that it's only a tiny amount required and like vitamins, or oil in your car, once there is enough adding more is no help and adding much more is bad news.
  23. Marquis is right, I remember that zinc is toxic to yeast in higher concentrations, maybe 2 mg/L.
  24. far333

    far333 Advocate (640) Connecticut Nov 16, 2002

    Palmer recommends .5mg/L max before causing yeast to produce excessive by-products leading to off-flavors, but does not mention toxic levels.
  25. VikeMan

    VikeMan Advocate (740) Pennsylvania Jul 12, 2009

    This paper talks about zinc toxicity to yeast...

    http://mic.sgmjournals.org/content/129/11/3421.full.pdf

    Excerpt: "This was in contrast to the rapid loss of viability of S . cerevisiae above a threshold level of 0.1 mM-ZinC
    (Fig. 3)."

    I don't know if/how this would translate directly to a brewing situation, and my molar concentration kung fu is a little rusty.
  26. Looking over the NHC presentations, optimal levels are in the .2 to 2 ppm or mg/L range. There was one graph that showed that at 10 ppm the fermentation completed, but was a little slower.

    I might put a full tablet in next time. The yeast take up the zinc in the first hour of the lag phase, then use it for the growth phase.
  27. mountsnow1010

    mountsnow1010 Savant (360) Vermont Jan 23, 2009

    I just have to say that this has been a very interesting thread to follow; I love to see the hard science approach to brewing!
  28. mountsnow1010

    mountsnow1010 Savant (360) Vermont Jan 23, 2009

    Interesting paper. That would indicate that a soln of > ~8.1 micrograms/mL would be toxic to yeast....much lower than the previously mentioned concentrations of 0.5-2 mg/mL....several fold lower in fact.

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