Zinc usage - amount for healthy fermentation

[cactusgarrett]

Instead of necro'ing an almost ten year old thread, I thought I'd spin up a new one regarding zinc usage for healthy fermentation for anyone doing math for themselves.

Recent generally accepted sweet spot for elemental zinc seems to be 0.3 ppm into the fermenter (that is 0.3 mg zinc per 1 L wort). However, this gets convoluted a bit since you need to take into account your form of zinc (ex. heptahydrate, monohydrate, etc.). For this purpose, I'm examing the heptahydrate (because that's what I have on hand). There's 22.8% elemental Zn in ZnSO4*7H2O (heptahydrate), so the info in the OP of that other thread would actually yield about 0.114 ppm elemental zinc instead of what they thought was a 0.5 ppm target.

The OPs prep matches closely with what BSG recommends on the low end (0.5-1.0g per 10 HL => 0.5-1.0 ppm), translating to 0.114-0.228 ppm elemental zinc.

I crunched numbers for my own purposes (6.5 gal into fermenter) and what I'd need to prepare and perform:

• Stock Solution: 494 mg into 100 mL water
• Working Solution: 5.0 mL of stock solution into 6.5 gal wort => 0.228 ppm

(obligatory "show my work" and imperial/metric conversion section)
5.0 mL x 4940 mg/L x 1L/1000mL x 22.8% ÷ 6.5 gal x 1 gal/3.8 L = 0.228 mg/L (ppm)

Obviously your preferences and targets will vary.

 

[cactusgarrett]

Just to clarify that this is such a nuanced subject, as to get detailed it does depend on yeast growth and viability. Not to mention there's work done to show that lager yeast need less than ales - target 0.05-0.15 ppm (MBAA Ep 041, around the 15:30 mark)

 

[DavidWood2115]

Very timely post. Craft Beer and Brewing has a recent episode on fermentation health, with a deep dive on zinc at around the 21 minute mark link. I thought it was fascinating.

My main take aways:
* Cold side zinc addition is better, as studies show that 60% of hot side zinc is bound up in trub.
* Premix Zinc Sulfate in acidified RO water and autoclave (pressure canning) to sterilize; can easily make a year or two's worth of home brewing amounts in one batch.
* Barley malt has about 100ppb of zinc, so add ~200ppb to reach sweet spot of ~300ppb or .3ppm
* Dosing at the high end of the BSG recommendation seems about right: 1g/10hL
* Lagers are actually more sensitive to yeast health, so zinc dosage is more important. This may be because off flavors are more noticeable?

I have yet to add this to my process, but it's on my list.

 

[bierhaus15]

Dialing in zinc is one of the biggest positive leaps you can make for beer flavor and quality. The number of pro brewers who don't do any of this is mind boggling. All good info above, but I'd add if you start doing this, target 0.3 ppm zinc for ales and 0.2 ppm for lagers. Zinc is also cumulative, so it often takes a couple generations to see full effects... so if collecting yeast, make sure to harvest when fermentation is complete and re-use within a week, ideally.

For a 1% zinc solution, 2.75 ml in 5.5 gallons is 0.3 and 1.8 ml is 0.2 ppm.

 

[cactusgarrett]

Very timely post

Yep - one of the reasons I started digging so hard into it. Nice callout.

 

[cactusgarrett]

target 0.3 ppm zinc for ales and 0.2 ppm for lagers

I understand this changes, too, when your grainbill changes. Higher percentages of adjuncts will need higher amounts of zinc, but at that point people have recommended the use of a general nutrient that conains FAN as well as Zn when you're looking at 60% wheat, etc.

I think the end target is 0.3/0.2 ppm, but I keep hearing that 0.1 ppm is carried downstream via the malt, so it's advisable to add 0.2/0.1 ppm yourself. I don't know how much merit there is to this claim, though.

 

[Erik the Anglophile]

Doesn't grain contain zinc and magnesia in such amounts that adding additional amounts won't really do anything?

 

[DavidWood2115]

Check out the podcasts in the first couple of posts. Most of the zinc in the boil is bound up with proteins et al. Adding zinc to the fermentation gets it where it needs to be.

 

[HighVoltageMan!]

I have actually switched to cold side additions of yeast nutrient after listening to the Craft Beer and Brewing podcast. I’m not sure it made a huge difference, but the sulfur production is lower (I make mostly lagers). I’m not sure if it’s the nutrient or the high levels of FAN in the starter which also reduces sulfur. Flavor is mostly unchanged so far.

Without some lab work, it’s very difficult to get an accurate measure of dissolved zinc in the wort since other ingredients also contain some zinc. I just add Wyeast nutrient to the fermenter by boiling it in a cup of distilled water, cooling it and adding it before the wort and yeast.

The reason I use Wyeast is because I really don't have another good source. It takes such a small amount to hit the .3ppm level with only a 7 gallon batch, I risk over dosing. The other thing to consider, is making sure that if you make a starter, the zinc levels are up in that wort. I add a big dose of organic yeast nutrient (autolyzed yeast) to the starter to make sure the lager yeast is heathy. The organic yeast nutrient contains some zinc.

 

[AlexKay]

Doesn't grain contain zinc and magnesia in such amounts that adding additional amounts won't really do anything?

My understanding of the conventional wisdom is that all-malt grain bills contain all the nutrients needed, except for zinc. Wort contains some zinc, but not enough.

I'm looking at my notes, and I add 0.1 mg/L hot side for ales and 0.2 mg/L for lagers. It's been long enough that I don't remember which sources I consulted to arrive at these numbers.

I found it to be more than a bit of a hassle to find zinc compounds that were explicitly labeled as food grade. I eventually found this, which I dose using a micropipette, and so one bottle will last forever. I think I've also found food-grade zinc gluconate. Brewery suppliers do sell bulk zinc sulfate, but in unreasonably large packages.

2 ppm zinc gives better foam. Fermentation consumes virtually all available zinc, though, so zinc for foam has to be added at packaging.

 

[MaxStout]

I add Wyeast nutrient on the hot side, about 1/2 tsp for a 5 gallon batch. The ingredient list for the WY nutrient mix says it contains zinc, but I am unable to find anything online that quantifies that. Wyeast states it is a "proprietary mix."

I might order the zinc solution drops that @AlexKay linked above, and use some to bolster the zinc in the wort. Maybe 1-2 mg/L. I know that zinc can be toxic to yeast but I believe that would require a much greater amount to be a problem.

 

[Group W]

What about throwing a new US penny in the fermenter? They are 97.5% zinc, 2.5% copper (copper plated zinc). Buff the copper off.

 

[mashdar]

What about throwing a new US penny in the fermenter? They are 97.5% zinc, 2.5% copper (copper plated zinc). Buff the copper off.

US pennies have ~2.4g of zinc based on initial googling. Sounds like a huge overdose.

And personally, copper in acidic foodstuffs sketches me out.

 

[Group W]

The penny isn’t going to dissolve, and a little copper won’t hurt. I’m just going to wire wheel a penny a little and try it. If it helps it will just be my secret weapon.

 

[HighVoltageMan!]

The ingredient list for the WY nutrient mix says it contains zinc, but I am unable to find anything online that quantifies that.

Here you go:

https://www.homebrewtalk.com/threads/wyeast-beer-nutrient-minerals.334882/

 

[MaxStout]

Here you go:

https://www.homebrewtalk.com/threads/wyeast-beer-nutrient-minerals.334882/

Interesting, thanks.

OP in that thread claims 0.635ppm Zn at 1 tsp per 5 gallons wort. My post-boil vol is typically closer to 6 gal, so more like ~0.5 ppm. Plenty o' zinc.

Won't need the drops, after all.

 

[AlexKay]

What about throwing a new US penny in the fermenter? They are 97.5% zinc, 2.5% copper (copper plated zinc). Buff the copper off.

Penny does not count as "explicitly labeled as food grade."

I wouldn't do it, but that's just me.

 

[MaxStout]

The low pH of wort will dissolve some of the zinc penny. The question is: how much will dissolve?

 

[Bramling Cross]

* Cold side zinc addition is better, as studies show that 60% of hot side zinc is bound up in trub.

Jennifer Talley's fantastic Session Beers: Brewing for Flavor and Ballance already has me adding salts, to noticeable effect,* post-mash, to make up for those that get trapped in the mash, so this makes sense.

Not having read this article and relying upon Wyeast nutrient @10min, would you suggest that the nutrient might be more usefully added as a whirlpool addition? Perhaps at ~150F? That should keep it from precipitating out with the trub, right? The mead guys just add it to the fermenter, right? I've often thought about that...why not?

Thank you, both! I'm eager to start messing around with this data!

*This isn't the same as Brungard's advice about withholding salts from your mash, later to be added. Talley is, instead, arguing that you should reinforce salts lost in your mash. Very different, and a big improvement in my ales/lagers and more in line with this discussion.

 

[k-daddy]

My understanding of the conventional wisdom is that all-malt grain bills contain all the nutrients needed, except for zinc. Wort contains some zinc, but not enough.

I'm looking at my notes, and I add 0.1 mg/L hot side for ales and 0.2 mg/L for lagers. It's been long enough that I don't remember which sources I consulted to arrive at these numbers.

I found it to be more than a bit of a hassle to find zinc compounds that were explicitly labeled as food grade. I eventually found this, which I dose using a micropipette, and so one bottle will last forever. I think I've also found food-grade zinc gluconate. Brewery suppliers do sell bulk zinc sulfate, but in unreasonably large packages.

2 ppm zinc gives better foam. Fermentation consumes virtually all available zinc, though, so zinc for foam has to be added at packaging.

Interesting. What is your exact dosing rate when using this product and how do you split the dose between pre and post fermentation?