7

Yeast follow the laws of natural selection. As a cell is budding the new mass may have some minor defects / mutations. If those changes give the yeast an advantage to survive it will get passed on. You can have noted changes in just a few generations. I've observed in my own washing methods strains becoming less flocculant just because my washing method ...


6

Yes, I have saved tons of money by growing my own yeast. It just takes a little planning and time. Slants or glycol storage are going to be your best bet. Get a pressure cooker to acts as a makeshift auto-clave for sterilization. With some yeasts coming in at $6-$9 a vial, this will help you get the most out of that money. In fact I have pulled proprietary ...


5

CO2 in suspension will cause bubbles to come out of the airlock long after the fermentation is done. It is an indicator, but not a precise one. Experience will tell you that for a particular yeast/wine, fermentation takes, for instance, 5 days to complete if all parameters are identical. Again, it is not precise. You should get an hydrometer and mesure ...


5

I do this about once or twice a year. I'm an all grain brewer, so I typically just brew a batch of base malt. You can do the same with buying some DME/LME and adding that to the right amount of water to get the SG around 1.035-1.040. Your process sounds good, although I would probably blend all the DME and water at once so you can check the SG, and then ...


4

It looks like you streaked several times from the same sample of yeast, and that there was a bit too much liquid in each streak (they resemble puddles). The liquid should be nearly invisible on your when applied to the plate. Also the plate surface should be a bit dry, so liquid is absorbed quickly. The streaking technique is important too: the plate in the ...


4

'So what exactly is 4 - 6 generations? [...] Are all of those considered generation 2?' A generation of yeast is considered as having gone from pitching to post-fermentation collection. So if you ferment a batch with new yeast and collect five jars, those are all first generation. If you pitched every one of those jars into a new batch and collected five ...


3

During the aerobic phase there is a presence of oxygen in the brew, during this phase there is a rapid increase in yeast and an almost exponential growth of yeast. During the anaerobic phase there is an absence oxygen, this causes the yeast growth to slow down and almost come to a halt. This since yeast does not grow well 'anaerobically' but needs the ...


3

I assume they're all different re-pitches of the same original strain? Certainly you would want to keep different strains apart so you can pitch based on their desired properties. But even still, I would keep the harvested yeast separate, if only so you can use them in a FIFO order of collection. The method you're using the harvest yeast has a reliable ...


3

The Wyeast smack packs have a small nutrient pouch inside the main pouch (which contains the yeast slurry). The nutrients will cause the yeast to "wake up" and consume the sugars in the nutrient liquid, causing the swelling. However, this is a function not only of the yeast, but also of the date of manufacture, the viability/vitality of the yeast and the ...


3

"Does it contain the same yeast strain as heffe, or not?" It's quite possibly the same strain BUT not necessarily the strain you're looking for (Weihenstephan's Hefe yeast). Bottle conditioning for one or both (or neither) of these beers may be conducted with different yeast strains than the primary (from which all of the characteristic hefe flavor comes), ...


3

Gelatin will help clear beer, but will not reduce or help pack down yeast sediment in bottles. To do that, you need to allow the yeast to settle longer or in colder conditions (fridge), or both. But you will not be able to drink from a bottle without yeast. To fine with gelatin to make your beer clear, you should do it in the fermenter. Mix 1 tsp. of ...


2

Monoammonium phosphate and diammonium phosphate contain all the same chemical compounds (phosphate ions, ammonium ions, and hydrogen ions), the major difference is that MAP has a second hydrogen in place of the ammonium. So, if you buy food grade stuff, it should be totally safe to consume, however, pH is determined by those hydrogen ions, so your wine may ...


2

I was able to find at least one paper in which a standardized wort was used to classify many (153) yeast strains based on, among four other parameters, degree of attenuation. The wort used was an 'All-malt hopped wort (specific gravity 1040, pH 5.0, attenuation limit ca. 1006) [...] prepared according to [another paper]...' This second paper referenced ...


2

I have veiwed a few papers and this one contained similar proportions to other references but was the only one to contain a reference for the source of the proportions. Isolation and Characterization of Brewer's Yeast Variants with Improved Fermentation Performance under High-Gravity Conditions Which references: 8.6.1 Fermentability, Attenuation Limit of ...


2

Most of the yeasts have both qualitative and quantitative notes that describe the flavor profile and other characteristics (flocculation/clarity, attenuation, temperature effects, &c.) The YeastBot Database is an attempt to centralize some of this information. I usually try to find a yeast that's in the same sort of family as the style I'm trying to ...


2

If you practice good sanitation. Decant the water off and combine to save space.


2

I suspect that the source of the infection was glycerin I used, since I perhaps erroneously assumed it should be sterile from a previously unopened container. I found citations that Sporobolomyces in particular had been isolated from "technical glycerin". Will now run my glycerin supply through the pressure cooker "autoclave". (My wife, trained as a ...


2

If you don't have an hydrometer, just keep a close eye to the airlock and give it a few days (3-5) after the activity has stopped. Mind that this is not the correct way to do that and there's no guarantee that your fermentation has finished. The only proper way to know that is to take periodic measurements of the density and determine when the gravity has ...


1

If you have no other instrumentation, look at the airlock. If the brew is fermenting, there is always going to be positive pressure against the liquid in the airlock, even when fermentation is relatively slow. If the room temperature drops and the liquid seems to be creeping back towards the brew, this indicates negative pressure, and suggests that ...


1

There is no set time and no set form that the mutation will take. But in general, mutations take a long time to happen. Years is the time line often cited.


1

You want to grow the slant up to about 100b cells by a mini starter, I start with 500ml 1.040 with nutrients. Then treat that as I would a new pack of yeast. Each step up of a starter takes 12-24 hours generally. Stirplate will help a lot to give more growth in shorter times.


1

A slant/plate made directly from a starter will likely stay viable longer than that picked up from trub. I'd estimate under decent conditions it should be good for up to about 6 months.... longer if under optimum conditions. But like Evil Zymurgist said, there are many, many factors at play here.


1

There are really too many factors to give a solid time frame when all the cells will have died. I've had year old trub I've been able to make starters from. If I had to pick a safe age I would reslant a precious strain ever 3-4 months.


1

Yeast is usually categorised by how well they flocculate, the esters and phenols they release and the attenuation you can expect. A "standard" American yeast (US05) is descibed as "clean", whereas your "standard" British yeast (S04) is described as fruity. Your weiss yeasts would be very fruity with high banana and spicy with clove. A lager yeast might be ...


1

You might be interested to look up Krebs cycle and the electron transport chain which yeast follow when in its aerobic respiration phase. This is when the yeast can create a ton of energy and that surplus of energy is used to replicate. After the oxygen runs out, it goes into anaerobic processes where the yeast produce CO2, ethanol, and sometimes lactate ...


1

Multiple single strain fermentation followed by blending gives much better control over the combined yeast character and is way more reproducible. It goes like this. Split the batch into multiple fermenters, innoculating each with a different yeast strain. You can split the wort volume equally the first time you brew the recipe. Ferment each part optimizing ...


1

I have been banking my yeast when I buy a new strain. Instead of cropping and washing, though, I overbuild my starter, then save half of that yeast. This save a lot of mucking about with washing and rinsing, and means that what I have stored is essentially first generation yeast. I find it really handy, and now have a freezer full of nearly pitchable ...


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