I wonder about the 1.040 starter gravity one reads often. Several people that are very knowledgable about yeast have said something in the 1.028 to 1.032 range is very good for growing cells.
This is a great thread. I thought I knew all I needed to know about starters. I’ve even printed a couple of posts for future reference. Thanks S.C!
Ditto that! Starters are where I’m putting a lot of my effort the last few batches, still working on it… Thanks all!
AFAIK, Wyeast and others are around 1.020 for yeast propagation. I try to keep to the low end, 1.030ish.
Do any of you guys make allowances for yeast age and yeast viability? Ive been using brewers friend yeast starter calc and/or the mr malty calculator…those usually have me doing at least 1L starters with one vial of white labs yeast for 3.5 gals (Yeast is usually > 2 months old). Usually target a starter gravity between 1.030 and 1.040.
So I tried this. 2L of pre canned 1.035 starter on stir plate 18hrs, chilled 6 hrs while I brewed, then pitched at 62 with temp controller set at 65. Pitched at about 8 pm yeserday. Checked it this morning and its rockin and rollin.
+1
I chose 1.030 as my basic starter gravity because it strikes a balance between optimum cell growth conditions and and preparing the cells for the higher osmotic pressures encountered in fermentation.
With that said, a 5% w/v solution (1.020 S.G.) is optimum for basic cell propagation because it provides enough nutrient for cell growth while placing low osmotic pressure on yeast cell walls. It’s also easier to dissolve oxygen into 1.020 wort than it is 1.040 wort. The autoclaved 40ml first-level starters that I inoculate from slant are 1.020.
A true 10% w/v volume solution has an specific gravity (S.G.) of 1.040. Mixing 100 grams of DME into 1L of water should result in a S.G. of approximately 1.036 because it is a 9% w/v solution. If the solution is boiled for 15 minutes, the resulting S.G. should be between 1.038 and 1.040 after it has been cooled to room temperature depending on the evaporation rate.
More good info. I’ve always used 1.020 starter wort for my first step when culturing bottle dregs because I thought it was a good idea. Glad to get some validation of that practice.
That sounds like a tiny bit of yeast that you are putting in to your starter. Can you estimate how many cells you are grabbing with your loop, and how many cells you end up with after your starter?
Indeed, this is very interesting and likely to change my starter routine, but I have to ask, considering how the commercial breweries repitch their yeast at the end of primary fermentation (as well as many homebrewers) - how important is it in the final product? I know that the breweries repitch for the economical reasons, but if it was an inferior product that resulted it would certainly affect their bottom line.
Is it quantity vs quality? If you have daily access to gallons of yeast I guess you can pitch as much a you see fit.
Mac
Brewers repitch for more than economical reasons. A yeast culture rarely performs at its best on the first pitch. Repitching acclimates a yeast culture to one’s brewery. Environment impacts how a yeast culture expresses it’s genotype (a.k.a. it’s phenotype). Environmental conditions can also cause genetic drift, not all of which are negative (i.e., if one repitches a yeast strain enough times, it will become a different yeast strain). A good example is Harveys Brewery in Sussex, England. Harveys has been repitching the same culture for over fifty years.
Some small places I know will repitch until they see a need for a new order from the yeast supplier. This is done mainly by taste.
One speaker at the NHC said they go 5 repitches before reordering.
Some big breweries have yeast propagators, so they can grow up large pitches in house from their yeast bank. These breweries have labs with trained personnel to take care of the yeast.
Growing yeast from a slant is not a single step process. It requires one to two steps of growth before inoculating a 1L starter. The standard step ratio is 10:1, that is, 10 milliliters of autoclaved 1.020 wort is inoculated aseptically from a slant. That culture is stepped to 100 milliliters, which is used to inoculate a 1L starter. Each step requires an incubation period. I am confident enough with my process at this point that I start by inoculating 40 milliliters of wort that has been autoclaved in a 100ml media bottle. I then step this culture to 600 milliliters, which is a 15:1 increase in volume.
40 milliliters of autoclaved wort in a Corning 1395 100ml media bottle
A few of the Alan Pugsley-built breweries have repitched the same Ringwood culture since they opened. I am fairly certain that Shipyard and Magic Hat are members of this group. One of the beauties of Ringwood is that it is true top-cropper. All of the Pugsley-built breweries top crop from open fermentation vessels. Top cropping is the only way to go if one wants to repitch a culture indefinitely (Harveys also top crops).
Arcadia is supposed to be one as well.
Minor thread hijack about starter gravity. I asked Chris White about this via email right before his yeast book came out (because I’m an impatient bastard)
Here is his reply:
[quote]Hello. Thank you for your comments and for using our yeast. To really eliminate the crabtree effect, you need to be down under 1.010, and slowly feed the yeast sugar. But 1.025-30 is still a good range, and I think it is a good compromise to good yeast physiology and good fermentation. So I think that is the best gravity, and brewers wort with grain, liquid, or dry malt are all good. Thank you, enjoy the book,
Chris
[/quote]
I use the 100 gram + 900ml water ratio because it does not require math. I think that gets me at about 1.036. I add the DME to the flask then fill the flask to my desired volume. Making a half strength starter is easy as well.
Edit. Fixed 900ml
Yes Arcadia uses Ringwood. One of the Brewers said it was a “Fussy Bitch” in that it would require more attention some times, ie rousing.
Grizzly Peak in Ann Arbor had a Pugsley system and would struggle with Diacetyl. They changed to Essex and the beers are much improved. They open ferment and top crop. The problem is they don’t have the tank time for a long D rest, they were doing close to 1600 barrels on a 7 barrel system. WLP -022 produces clean beer for them.
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Let’s work out the amount of DME needed to get below the Crabtree threshold using Briess Pilsen Light DME, which is specified as containing 14% glucose (Find Your Perfect Malt - Brewing With Briess). The Crabtree threshold is 0.3% glucose w/v. With Briess Pilsen Light DME, the Crabtree threshold lies at 0.003 / 0.14 x 100 = ~2.14% w/v, or an S.G. of a little more than 1.008. We need to stay below this value in order to maintain aerobic growth; hence, an S.G. of 1.008 should do it (0.02 x 0.14 x 100 = 0.28% glucose w/v). We can go lower; however, we are talking about a nutrient source that will be consumed fairly rapidly. Maltotriose and higher-order saccharides make up almost a third of Briess Pilsen Light DME. Many strains are limited in their ability to break the glycosidic bonds that hold the three glucose molecules in maltotriose together. Strains such as Windsor cannot do it at all, which is why it leaves a high terminal gravity.
In order to grow yeast aerobically, we need a way to maintain the carbon source (sugar) and the dissolved oxygen level at a steady state. This type of process is known as a chemostatic process. The device used by the big boys to produce dry yeast aerobically is called a bioreactor. Bioreactors propagate yeast aerobically in a continuous process where yeast cells are drawn off while nutrients and oxygen are added.
As an aside: a tower fermenter is a bioreactor in which beer is continuously drawn off of the top while nutrients are added at the bottom. Whitbread B (a.k.a. NCYC 1026, Wyeast 1098, WLP007, and S-04) was selected for use in tower fermentators (click on strain information on this page: https://catalogue.ncyc.co.uk/saccharomyces-cerevisiae-1026). That’s why it’s the cockroach of yeast strains. Whitbread B is a seriously hardy yeast strain.