Best Practices - Zinc Addition

Best Practices - Zinc Addition

In an ideal world, barley malt provides sufficient nutrition for yeast health and performance with the exception to zinc. While we recommend brewers supplement wort with a complete yeast nutrient such as Yeast Lightning Nutrient, some brewers prefer to add only zinc. 

Why is zinc important for yeast health? 

Zinc plays a key role in yeast metabolism because it is a cofactor in key fermentation enzymes. In particular, alcohol dehydrogenase enzymes that help convert acetaldehyde to alcohol require zinc as a cofactor.

How do I give my yeast enough zinc? 

Most high-quality yeast nutrient blends such as Yeast Lightning are formulated to contain an appropriate quantity of zinc, so these are a great option to conveniently add zinc to your wort. 

If not using a nutrient blend, most brewers will use a hydrated zinc salt such as zinc sulfate heptahydrate (ZnSO₄ x 7H₂O). 

In general, most brewers target between 0.1-1 ppm of elemental zinc in wort. In general lager yeasts need less zinc and ale yeasts need more. In both cases, While 1 ppm is technically an excessive amount, solubility of zinc additions in wort is often inefficient as the zinc can be precipitated in trub. 

How much zinc do I get from Yeast Lightning Nutrient? 

At the standard dosage rate, Yeast Lightning will provide your yeast with 1 ppm of bioavailable zinc (updated January 2024). This type of zinc is easier assimilated by the yeast. If you are currently adding zinc sulfate to your wort and switching to Yeast Lightning, we recommend cutting your typical zinc addition in half since you get some zinc from Yeast Lightning. 

How do I calculate how much zinc to add? 

Time for some math! 

Zinc ions are 22.8% of the molecular weight of zinc sulfate heptahydrate (65.3 out of 287g/mol).

To get to 1 ppm zinc, we need to add 1/0.228 = 4.39 mg/L (ppm) of zinc sulfate heptahydrate.

So to get to our range of 0.1 - 1 ppm zinc, this would translate to a measurable quantity of between 0.04- 0.44 g per 1hL (100L). To shoot for the middle, 0.2 g per 1 hL would be appropriate. This translates to 2 g in 10 hL of wort. 

Keep in mind that zinc solubility is never 100% efficient, and this efficiency is not consistent between brewhouses. You may need to dial in the amount you add upward or downward based on the yeast performance you observe. 

Remember to factor in the zinc concentration of your source water. 

Best practice for zinc addition in the brewery 

NOTE: As of January 2024, Yeast Lightning with lot codes starting with "24" contain a higher concentration of zinc and does not requre further addition of zinc.

Here is our recommended nutrient regime, including zinc addition. This especially works well to boost Lager yeast fermentation and repitching performance: 

Yeast Lightning - 4g/hL, added at whirlpool 
Zinc Sulfate Heptahydrate - 0.2g/hL, made into a sterile solution and added directly to the tank 

We recommend both Yeast Lightning and Zinc because they offer different benefits and are ideally added to the wort at different times in the process. Adding the zinc to the fermentor helps avoid the solubility problem mentioned above, since zinc added in the brewhouse will partially precipitate with the trub. 

Additional Resources

- MBAA members can access a fantastic presentation on zinc from Joe Kinney. 

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