Optimizing Yeast Nutrition!


Yeast converts fermentable sugars into alcohol. Sugar levels, temperature, oxygen levels, pH, and nutrients in the yeast’s environment all play an important role. Today, we investigate nutrition. Healthy yeast creates a higher yield and a faster ferment. So let’s dive in deeper and find out what nutrients it needs in order to perform!


Why does yeast need nutrition? Doesn’t it come fully functional? It does, but – just like you and me – yeast needs nutrients to keep going. And there is more. Yeast, in an oxygen-rich environment, so especially at the beginning of your fermentation cycle, multiplies. One yeast cell becomes two, then four, then eight, then sixteen, etc. Without additional nutrients, the available nutrition would have to be divided between more and more cells.


Yeast Assimilable Nitrogen (YAN) is very important. During the first 72 hours of your fermentation, the yeast will absorb it. During the fermentation, YAN is used to synthesize proteins, amino acids, other building blocks, that are essential to the yeast and its ability to produce alcohol.

A lack of YAN leads to an increased production of glycerol at the cost of alcohol production. YAN deficiency can decrease total alcohol yield by up to 10%. Put differently, by adding enough nitrogen, the craft distiller can potentially increase his yield with 10%!

But there is more. A lack of YAN also results in less esters and acids being formed. If you are educated in Odin’s Theory of Fermentation, you will immediately understand that this is bad for overall flavor development.

The optimal amount of nitrogen is 267 mg per liter. Amounts below 140 or above 400 mg per liter will result in non-optimal outcomes. The yeast may stall and stop producing alcohol all together.

To prevent such a situation from developing, add 0.6 grams of di-ammomium Phosphate (DAP) per liter.

Zinc sulphate

Zinc sulphate is another essential nutrient to yeast growth and performance. The yeast cells use it to grow. It is also a source of energy, via the production of NADH and NAD+. and it increases alcohol tolerance. Off the yeast, not of the consumer. 😉

Zinc improves the production of ethanol. Zinc ions help the yeast create vitamine B2, essential to yeast growth.

Zinc sulphate is absorbed during the first 48 to 96 hours of the fermentation. An ideal level is 0.4 mg per liter of fermentation. Values above 0.6 or below 0.1 mg per liter will result in the yeast stopping to function.

Add 0.0004 grams of zinc sulphate per liter.

Copper sulphate

Copper ions and zinc ions can react and form a superoxidedismutase. That word helps you win at Scrabble. It is also an enzyme that catches biradical oxygen atoms, that are toxic to the yeast, and turns them into O2, oxygen, which is exactly what it needs.

Copper ions help induce metallothioneïnesynthesis, which helps bind heavy metals, that would otherwise harm the yeast cell. It is also essential to the yeast’s metabolism and growth.

Add 0.001 grams of copper sulphate per liter.


Mash or otherwise mix substrate with water. Bring the mix to fermentation temperature. Add the above nutrients and mix them in. After that, add the yeast.

For more reading

Please see:

1.        Asif, H. K. et al. Comparative study of bioethanol production from sugarcane molasses by using Zymomonas mobilis and Saccharomyces cerevisiae. African J. Biotechnol. 14, 2455–2462 (2015).

2.        Arroyo-López, F. N., Orlić, S., Querol, A. & Barrio, E. Effects of temperature, pH and sugar concentration on the growth parameters of Saccharomyces cerevisiae, S. kudriavzevii and their interspecific hybrid. Int. J. Food Microbiol. 131, 120–127 (2009).

3.        Mendes-Ferreira, A., Barbosa, C., Lage, P. & Mendes-Faia, A. The impact of nitrogen on yeast fermentation and wine quality. Cienc. e Tec. Vitivinic. 26, 17–32 (2011).


5.        Albers, E., Larsson, C., Lidé N, G., Niklasson, C. & Gustafsson, L. Influence of the Nitrogen Source on Saccharomyces cerevisiae Anaerobic Growth and Product Formation. APPLIED AND ENVIRONMENTAL MICROBIOLOGY 62, (1996).

6.        Mendes-Ferreira, A., Mendes-Faia, A. & Leao, C. Growth and fermentation patterns of Saccharomyces cerevisiae under different ammonium concentrations and its implications in winemaking industry. J. Appl. Microbiol. 97, 540–545 (2004).

7.        Pretorius, I. S. & Henschke, P. A. Title: Influence of diammonium phosphate addition to fermentation on wine biologicals Mar Vilanova [1].

8.        Brice, C., Sanchez, I., Tesnière, C. & Blondin, B. Assessing the mechanisms responsible for differences between nitrogen requirements of saccharomyces cerevisiae wine yeasts in alcoholic fermentation. Appl. Environ. Microbiol. 80, 1330–9 (2014).


10.      Zhao, X.-Q. & Bai, F. Zinc and yeast stress tolerance: Micronutrient plays a big role. J. Biotechnol. 158, 176–183 (2012).

11.      Zhao, X. Q. et al. Impact of zinc supplementation on the improvement of ethanol tolerance and yield of self-flocculating yeast in continuous ethanol fermentation. J. Biotechnol. 139, 55–60 (2009).

12.      Raj, S. B., Ramaswamy, S. & Plapp, B. V. Yeast alcohol dehydrogenase structure and catalysis. Biochemistry 53, 5791–803 (2014).

13.      De Nicola, R., Hall, N., Melville, S. G. & Walker, G. M. Influence of Zinc on Distiller’s Yeast: Cellular Accumulation of Zinc and Impact on Spirit Congeners. J. Inst. Brew 115, (2009).

14.      De Nicola, R. & Walker, G. M. Zinc Interactions with Brewing Yeast: Impact on Fermentation Performance. J. Am. Soc. Brew. Chem. 69, 214–219 (2011).

15.      Šillerová, S. et al. Preparation of Zinc Enriched Yeast (Saccharomyces Cerevisiae) By Cultivation With Different Zinc Salts. J. Microbiol. Biotechnol. Food Sci. 2019, 689–695 (2019).

16.      Priest, F. G. & Stewart, G. G. Handbook of brewing. (CRC/Taylor & Francis, 2006).

17.      Vecseri-Hegyes, B., Fodor, P. & Hoschke, Á. The role of zinc in beer production. Acta Aliment. 35, 17–24 (2006).

18.      Walker, G. M., De Nicola, R., Anthony, S. & Learmonth, R. Yeast-metal interactions: impact on brewing and distilling fermentations.

Yeast Cell Division Caused Nutrient Deprivation …


Production Constrained, not Sales Constrained!

I remember when, after having produced iStills for about a year, we got the first real truck in. We needed a truck to get an order shipped to Scotland. A big order. A feeling of pride and accomplishment. The weird thing is, we now do about a truck per week. A truck of iStills per week, yet it never gets normal or boring.

Thank you all for your continued support, your orders, your feedback, and your success stories! It is a delight to work for you. It is amazing to see you all making a difference and putting an ever bigger dent into Big Alcohol’s industrialized mass production, one drop, one glass, one bottle, one iStill at a time.

The steep increase in demand for iStills does create its own set of challenges, though. We are nearing a situation of being production constrained rather than sales constrained. In plain English: we sell more stills than we make. iStill currently plans production batches as far ahead as January 2022.

What you can do about it, as a prospect iStill customer? Order as early as possible. That way lead times or future price increases won’t surprise you. What we’ll do? We’ll keep increasing our production capacity. For 2021 with probably another 15 to 25%.


Odin, CEO of iStill.


iStill 5000 Production & Assembly!

Here’s a picture of the iStill 5000. The unit is what we called “produced” and will now get “assembled”. With “production” we mean the actual metal cutting, bending, welding, cleaning, and insulation. With “assembly” we refer to the step after “production”, where we electrify the unit by adding the PLC, the cuts selector, the robot, the heaters, the probes, etc.

We just produced a new iStill 5000 for the Japanese whiskey market …


We invented a way to purify your heads and tails!

Willem’s Miracle Powder

Making careful cuts for hearts, leaves you with heads and tails losses. Well, here is the good news: as of today they are losses no more! iStill’s chemist Willem has tested a powder and designed a purification protocol, that will help you clean up your heads and tails to the extend that they will become your purest vodka or GNS. Want to learn more? Yes, you do, so let’s dive in deeper!

The Goal

Heads and tails are full of flavors. Mostly off-flavors, and that’s why you cut them out. But a deeper analysis learns us that the vast majority of those heads and tails are actually … hearts. Good ethanol, contaminated by small fractions of actual lower and higher boiling point alcohols and their associated flavor molecules aka esters.

The goal of Willem’s Miracle Powder? To recover this ethanol, but to get rid of the bad alcohols and bad flavors. Now, redistilling heads and tails during a vodka program on the iStill does a great job at getting rid of the bad alcohols. But the compaction of heads and tails, leads to the associated bad flavors to leach into the ethanol recovery.

Again, the goal of Willem’s Miracle Powder and this new procedure? To destroy the esters found in your heads and tails factions.

The Thought Process

If you have followed the iStill University, you have learned all about esterification and how flavor molecules are formed. You remember Odin’s Esterification Formula? And how a low pH results in more flavor molecules or esters being created?

Guess what, the opposite is true as well! If you make your heads and tails factions very alkaline, instead of acidic, you can destroy the alcohol-carbon bonds that make up the ester molecule. Treating your heads and tails factions and then distilling it in vodka mode, breaks up the esters, recovers the ethanol, and helps you turn what was a loss into the purest vodka or GNS possible.

The Procedure

  1. Add your heads and tails faction to the iStill;
  2. Dilute the heads and tails faction to 30% ABV;
  3. Add sodium hydroxide (0.4 grams per liter of diluted heads and tails faction);
  4. “Sodium hydroxide” as in caustic soda, also used by breweries to clean their stainless steel brewing equipment;
  5. Mix the sodium hydroxide in (be careful, this is not the stuff you want to inhale or get in touch with!);
  6. Start the vodka program;
  7. Choose the heads stabilization program to be at least 60 minutes;
  8. Distill as per usual;
  9. Toss heads and tails, keep hearts – the most neutral and delicious vodka;
  10. Treat the boiler content with citric acid to bring pH back to 7;
  11. Drain your boiler and rinse the system with water.

The Results

The results of the above procedure are amazing. The worst heads and tails turn into a beautiful vodka or GNS. That’s not just our opinion, but a scientific fact. Do you want to see some of the proof?

A chromatographic overlay of a 1% ethyl acetate solution (a heads faction) in purple, a 0.1% ethyl acetate solution in yellow, an untreated heads sample in green, and the black line (look careful!), that signifies the heads sample after treatment with Willem’s Miracle Powder (aka sodium hydroxide):

The above chromatographic analysis proves that iStill’s Heads & Tails Purification Procedure successfully removes the associated headsy esters from a heads (the graph title mistakenly says “hearts”) sample.

But that is not all! How does the procedure do against other heads and tails flavors? Well, here is the outcome of further CG analysis. In purple you see the various esters available in an untreated heads and tails sample. The black, line that is significantly lower, represents the ester count after the purification procedure:

But that is not all! This procedure, since you basically use a cleaning agent, also makes your boiler shine as if it were new.

The Conclusion

iStill’s Heads & Tails Purification Protocol works a charm. It allows the craft distiller that possesses iStill equipment to process former heads and tails losses and turn them into the purest vodka or (reusable) GNS.

The iStill is not a still, it is a distillery!

“Good morning Odin! I just wanted to share this with you because having made the right choice makes me feel really good. I have been mashing-in corn and barley, fermenting, and distilling non-stop for 2 months now. I have been able to process 1.7 tons of grain per month (all this on my own). All this would not have been possible without my iStill along with the rest of my setup, and the experience to manage all that, of course!”

Aristides Distilling uses an iStill 2000 to mash, ferment, and distill (in one run) whisky and bourbon …


One Stop Shop!


iStill is a one stop shop. As a craft distiller, you develop, produce, and sell your own spirits. We help you with each and every step. Why? Acquiring equipment without knowing how to make a great gin, rum, or whiskey doesn’t make sense. Making great product without knowing how to sell it, doesn’t make much sense either. That’s the “why”. Now, let us dive into the “how”.


To be able to distill great spirits, you first need to become a great distiller. The iStill University offers an amazing theoretical course as well as a hands-on follow-up course. The iStill Mini is the perfect training still and the perfect recipe development still. Our courses aim to help you become a craft distiller. This means that you learn how to create recipes, how to distill these recipes into quality spirits, and how to sell them and take advantage of market opportunities. As a graduated student, you can apply to the iStill University Facebook group, where over 300 fellow iStillers help each other out, asking and answering questions.


Our distilling equipment is based on 21st century theory and technology. Not on romantic ideas stemming from the 1800’s. You are opening a business, after all, and not a museum, right? Okay, so here’s what we offer: modern equipment with unparalleled process control. It helps make distilling easier. More controlled spirits production processes, so improved reproducibility, resulting in higher quality products at lower production costs. Again, you are a craft distiller, not the night manager at the Smithsonian.

Recipe development

Do you want your recipes and spirits to be top notch? Of course you do. We offer recipe development services that help you perfect your spirits. Together, our training and equipment and recipe development services help you win medals. See: https://istill.com/halloffame/