Author Topic: Zinc sources  (Read 7038 times)

KernelCrush

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Zinc sources
« on: May 23, 2014, 03:02:05 PM »
Been reading about getting the correct levels & sources of zinc.

One I read the guy said he uses collected rainwater to brew with and his roof is galvanized, so he is good.

Others suggest a piece of zinc plated hardware in the boil...evidently some German brewers have done this.

Then I found this exacting method.  From what I read it appears you don't want to exceed 0.6ppm

Zinc Solutions

 Two common sources of zinc are Zinc Chloride (ZnCl2) and Zinc Sulphate that normally has water attached to it (ZnSO4.7H20). This hydrated ZnSO4 is still a crystal, it just absorbs water from the atmosphere. You can get these from school labs or lab suppliers.

 In these examples we are looking at adding 0.4ppm of zinc to the final wort.

 ZnCl2
 Make a solution of 4.17g ZnCl2 (dry) per litre of de-ionised or distilled water.
 This solution contains 2mg of Zinc per mL.
 So for 20L wort you add 4ml to get 0.4 ppm Zn in the wort

 ZnSO4.7H20
 Make a solution of 35 grams of ZnSO4 per litre of deionised or distilled water.
 This solution contains 8 mg of zinc per mL.
 So for 20L wort you add 1ml to get 0.4 ppm Zn in the wort

Looks like a small quantity of ZnSO4.7H20 will get you a lifetime supply in a mason jar. 

Offline grathan

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Re: Zinc sources
« Reply #1 on: May 24, 2014, 11:06:55 AM »
Those are pretty small measurements . Could zinc be toxic to yeast above 0.5 mg/ml?
http://www.beeradvocate.com/community/threads/help-with-zinc-as-yeast-nutrient.58610/

What about just using Wyeast Yeast Nutrient. It claims to have adequate levels of all minerals required by yeast.


Offline Scott Ickes

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Re: Zinc sources
« Reply #2 on: May 24, 2014, 11:40:11 AM »
Those are pretty small measurements . Could zinc be toxic to yeast above 0.5 mg/ml?
http://www.beeradvocate.com/community/threads/help-with-zinc-as-yeast-nutrient.58610/

What about just using Wyeast Yeast Nutrient. It claims to have adequate levels of all minerals required by yeast.

I've seen different reported levels of zinc being toxic to yeast.  If you're using Wyeast Nutrient Blend, you're already getting some zinc.  If you add zinc from another source, in addition to the zinc in the yeast nutrient, you may go above the toxic level of the yeast.

In addition, if you have any brass fittings, you leach some zinc out of the brass with each batch.

I've googled Wyeast Nutrient Blend to find out how much zinc it adds to a 5 gallon batch, but couldn't find any numbers on it.  All I found is that it has zinc in it, but not how much.
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Offline Baron Von MunchKrausen

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Re: Zinc sources
« Reply #3 on: May 24, 2014, 11:54:09 AM »
This was posted by someone who contacted wyeast directly to ask what the mineral content was of their beer nutrient.
This was the response by one of the wyeast microbiologists:
______
At the recommended usage rate of 1/2 tsp (2.2 grams) per 5 gallons (19 liters) of wort, or 0.116g/liter, the mineral concentrations are:

Calcium 0.696 ppb (virtually zero ppm)
Magnesium 0.928 ppm
Sodium N/A (not a part of any of the major ingredients)
Sulfate 13.920 ppm
Chloride N/A (not a part of any of the major ingredients)
Bicarbonate N/A

As well as:

Zinc 0.635 ppm
Manganese 0.567 ppm
Thiamine 0.241 ppm
_______

As you can see, it is quite high in zinc.
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Offline Baron Von MunchKrausen

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Re: Zinc sources
« Reply #4 on: May 24, 2014, 12:02:33 PM »
As a side question.. (sorry, don't mean to derail the thread), I'm puzzled by the use of rainwater for brewing.
Rainwater is absolutely filthy. Granted, some methods of collection are better than others. I can't imagine collecting runoff from a galvanized roof. I doubt boiling can remove these impurities. It seems that many brewers use it so I must be missing something..
Can someone explain the purpose of using rainwater?
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Offline brewfun

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Re: Zinc sources
« Reply #5 on: May 24, 2014, 05:42:23 PM »
Could zinc be toxic to yeast above 0.5 mg/ml?

The first time I remember seeing a discussion about zinc in brewing was around 2000 or so. This was part of a much longer discussion on stuck fermentations and high alcohol styes. The question was which of the necessary nutrients was the "limit" factor. Meaning, which mineral, when exhausted, caused the yeast to slow and shut down.

The limit mineral quickly was thought to be Zinc, with the next two being Manganese and Copper. All of them being related to how much specialty malt and/or kettle sugars (i.e. Belgian Quads) was in the recipe. This went further into malt extracts and their notoriously low FAN levels.

There's a sweet spot of Zinc that is around .2 mg/l for ales and .3 mg/l for lagers. In that range, beer will finish faster and drier than without it. Both yeasts can handle amounts above .5 but the side effect is a longer lag time and a slightly metallic aftertaste.

Generally, an all malt beer doesn't need any nutrient to finish fermentation. All the nutrients needed are already in pale malt, along with the enzymes and starches. ...That's the thing about malt, it wants to become beer.

What the nutrient does is aid the yeast with flocculation and stasis. Basically, a preventative for autolysis and health enhancement for repitching. Kinda like a protein bar on a long hike.

The main thing is that once you feed the yeast with nutrients, the limiting factor is the sugar content. From that point forward, excess nutrient becomes food for contamination organisms.
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KernelCrush

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Re: Zinc sources
« Reply #6 on: May 29, 2014, 12:32:02 PM »
Here's the skinny on Servo & WLN1000.  Looks like WL doesn't make it.