Yeast

Misc Tips

London ale adjusts to a cylindrical conical fv in about 2 generations. So they use fresh pitches on their American wheat (white nose) cause that will stress it a little and gives it a touch of banana CBB 316 - Uberbrews

Life Cycle

Fermentation Time Line - Chris White

Lag phase, 3-15 hours after pitching yeast:

When yeast is pitched into beer, it begins a process of acclimation to the environment. This is known as the "lag" phase. The yeast begins to uptake minerals and amino acids (nitrogen) from wort. Amino acids are used to build proteins. The amino acids that yeast can not obtain or get fast enough from wort need to manufactured by the yeast. Much the same way that humans need 100% of essential vitamins and minerals to make it through the day, yeast cells also need 100% of their vitamins and minerals (nutrients) to make it through a fermentation properly nourished.

All-malt wort is an excellent source of nitrogen, minerals, and vitamins. Most of the vitamins yeast need for proper fermentation are supplied in wort. Some examples of necessary vitamins are riboflavin, inositol, and biotin. Important minerals are phosphorous, sulfur, copper, iron, zinc, potassium, and sodium. As the minerals and vitamins are taken up from the wort, yeast begins to manufacture enzymes necessary for growth. Wort can be supplemented with additional minerals and vitamins by using commercially available yeast nutrients, which will improve the health and performance of the yeast.

Oxygen is rapidly absorbed from the wort during the lag phase. The yeast need this oxygen to grow in order to produce important cell wall constituents. It is important to provide enough oxygen into wort at the beginning of fermentation. By shaking the fermentor, a homebrewer is able to, at best, add about half the recommended level of 10 ppm oxygen into solution. This will produce satisfactory fermentation results, but to make sure a healthy fermentation will take place, oxygen can be added to the fermentor with several commercially available systems.

The lag phase can be carried out at a higher temperature than the rest of fermentation because very little flavor compounds are produced. Ethanol production is also very limited, therefore ester formation is not a concern. Some brewers begin the lag phase for ales at 72-75F, and complete the fermentation at 68F. This can be done with success for lagers too, with starting the lag phase at 72-75F and lowering the fermentation temperature to 50-55F.

Brewers will not see any visible activity during the lag phase, hence the way it got its name. But this phase is very important in building new healthy cells that will be able to complete fermentation. If the wort is overpitched, this will decrease the lag phase, and each individual cell will not be as healthy at the end of fermentation. Although it may feel reassuring to a homebrewer to see fermentation activity within one hour of pitching yeast, it is not best for the yeast.

Exponential growth phase: 1-4 days:

As the yeast comes out of lag phase, it starts to consume the sugars in the solution. CO2 is produced, which starts to expel from the airlock and create a surface layer of foam on the beer. The exponential, or logarithmic, phase of yeast growth is now starting. During this phase, the cell count will increase rapidly, and ethanol and flavor compounds will be produced. Airlocks will bubble like crazy within this time frame. The aroma that escapes from the airlock of most neutral ale yeast fermentations has an "olive" smell.

The exponential phase occurs because yeast rapidly consumes the sugar. Wort sugar is consumed by yeast in a certain pattern. Glucose is used first, then fructose and sucrose. These are simple sugars, and can be quickly shuttled into metabolism. The glucose concentration in wort is roughly 14% of wort sugars.

Maltose is the centerpiece sugar of malt and is a very important flavor component. It makes up 59% of wort sugars, and its use by yeast gives beer its characteristic flavors. There are 1 to 5 genes in yeast DNA that "turn on" in response to maltose, allowing for fermentation by brewers yeast. After maltose enters the cell through a special uptake mechanism, it is hydrolysed into glucose units by maltase enzymes. Glucose can then enter the normal metabolism cycle.

Best Practices

Zinc

Best Practices - Zinc Addition (Escarpment)

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 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.

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

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.

Expat Brewers… What is an ingredient in your arsenal that often goes unnoticed or underappreciated? What do you like it in?

Zinc sulfate in everything ….
I’ve heard it’s good for pushing beers through fast and reducing acetaldehyde.
how much Zinc Sulphate would you recommend?
all depends on what kind of zinc sulphate you get. There's monohydrate and heptahydrate - the latter having 7 times the amount of water molecules and therefore ratio is different. ….
I still use it with fresh yeast. whilst packed with nutrients it's still quite a traumatic process for yeast - and if you want to build a healthy second gen with beautiful healthy cell walls, then zinc is perfect. ….

Oxygen

Oxygen Flow Rate (Reddit)

I know it’s generally supposed to be 8-10ppm dissolved oxygen for ales and more for lagers.
Gravity Points divided by 4 is a good starting point, for ppm for each batch - .044 / 4 = 11ppm. Lager yeasts needs extra and big beers above .052 need a boost. No meter equals guess work, which is where a lot of breweries start. Good luck!
For my 7bbl, knocking out through a 1 inch hose, that’s 30 foot long at 68 degrees, with an 8 inch sintered stone from glacier tanks. I use a DO meter to get me in the range of 12-18ppm for ales. I inject at around 0.3 LPM for the duration of the 30-40 min knockout. Its imperative to have DO meter for measuring it. It’s super easy to inject oxygen amounts that are toxic to yeast and will affect fermentation performance.
I have a 5 hL system and knockout at about 25 lpm / 22 C. Oxygen flow is about 0.15 lpm for duration of transfer, resulting in about 10-12 ppm.
A while back I did a bunch of experiments. For our stone and knockout procedure, 1.5 LPM was the best set point to get turbulent mixing. Any lower and the oxygen just floated on top of the wort and any higher and it causes foaming and huge bubbles that also didn't dissolve.