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Help with Zinc as yeast nutrient

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

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  1. far333

    far333 Poo-Bah (1,986) Nov 16, 2002 Connecticut
    Beer Trader

    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. marquis

    marquis Crusader (739) Nov 20, 2005 United Kingdom (England)

    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 Aspirant (200) Aug 3, 2012 New York

    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. kjyost

    kjyost Meyvn (1,174) May 4, 2008 Manitoba (Canada)

    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 Meyvn (1,335) Jul 12, 2009 Pennsylvania
    Beer Trader

    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 Poo-Bah (1,986) Nov 16, 2002 Connecticut
    Beer Trader

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

    far333 Poo-Bah (1,986) Nov 16, 2002 Connecticut
    Beer Trader

    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 Aspirant (200) Sep 15, 2006 New York
    Subscriber Beer Trader

    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. kjyost

    kjyost Meyvn (1,174) May 4, 2008 Manitoba (Canada)

    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 Initiate (0) Apr 30, 2010 Florida

    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. hopfenunmaltz

    hopfenunmaltz Meyvn (1,301) Jun 8, 2005 Michigan

    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 Initiate (0) Jan 23, 2009 Vermont

    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 Poo-Bah (1,606) Aug 13, 2005 Wisconsin
    Supporter Subscriber

    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 Poo-Bah (1,986) Nov 16, 2002 Connecticut
    Beer Trader

    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 Meyvn (1,335) Jul 12, 2009 Pennsylvania
    Beer Trader

    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 Poo-Bah (1,986) Nov 16, 2002 Connecticut
    Beer Trader

    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. Wolfsdenbrew

    Wolfsdenbrew Initiate (0) Jun 16, 2004 New Mexico

    Wow, sure glad I just buy Wyeast Nutrient!
  18. mountsnow1010

    mountsnow1010 Initiate (0) Jan 23, 2009 Vermont

    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 Disciple (308) Sep 1, 2004 New York

    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.
  20. hopfenunmaltz

    hopfenunmaltz Meyvn (1,301) Jun 8, 2005 Michigan

    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.
    far333 likes this.
  21. far333

    far333 Poo-Bah (1,986) Nov 16, 2002 Connecticut
    Beer Trader

    I'm only interested in zinc, and I'm a bit of a DIYer, and I seem to sometimes take the more complicated route. :slight_smile:
  22. marquis

    marquis Crusader (739) Nov 20, 2005 United Kingdom (England)

    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. hopfenunmaltz

    hopfenunmaltz Meyvn (1,301) Jun 8, 2005 Michigan

    Marquis is right, I remember that zinc is toxic to yeast in higher concentrations, maybe 2 mg/L.
  24. far333

    far333 Poo-Bah (1,986) Nov 16, 2002 Connecticut
    Beer Trader

    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 Meyvn (1,335) Jul 12, 2009 Pennsylvania
    Beer Trader

    This paper talks about zinc toxicity to yeast...


    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. hopfenunmaltz

    hopfenunmaltz Meyvn (1,301) Jun 8, 2005 Michigan

    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 Initiate (0) Jan 23, 2009 Vermont

    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 Initiate (0) Jan 23, 2009 Vermont

    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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