CnnmnSchnpps
Well-Known Member
I thought it was methylene blue that was typically used for yeast.
Yes it's methylene blue
I thought it was methylene blue that was typically used for yeast.
Control pitch: 0.75 million cells/ml/º Plato 32.9 billion cells.
Overpitch: 2.5 million cells/ml/º Plato 112.8 billion cells.
Underpitch: 0.1 million cells/ml/º Plato 4.7 billion cells.
Yup... IIRC (or if I'm confusing it with another dye process) it dyes dead yeast cells (i.e. no controll of what goes in or out) so you can get an idea of viability.
I'm wondering how you are going to take all those gravity readings with only .5 gal of beer to work with. Are you goind to keep dumping it back in? If so, contamination could easily throw off your results. Plus, getting up in the middle of the night to take 8 gravity readings is not on my list of things to do.
So for a starter are you saying make a 1L starter and take 100mL from the 1L and add that to the 2L and dump the rest?
that 100ml number comes from the assumption that you're making a 1L starter. if you're doing a 2L starter, make it 200ml, he said that you step in up series of 10. so like if i had a 20ml sample, start it in a 200ml starter, than step it to 2L.
just got back from the class! i want to give a huge thanks to brooklyn homebrew and jason the microbiologist for his very informative class.
the beginning of the class talked about the physical aspects of yeast cells and how they metabolize sugar into c02 and alcohol. he also brought slides of different types of yeast and we got to see them under a microscope. got to see 1056 budding and some brett, which is really long and rod shaped, unlike the spherical 1056. that part was cool.
he taught us a cool thing about how to check for diacetyl. you need two class, a cold water bath and a hot water bath, a thermo and some aluminum foil. pour some wort (fermented but before bottling) into the glasses and put one into the hot water and one into cold, covering with foil. let sit for 20min. then take the hot sample and put it into the cold water, you want to make them the same temp. take off the foil and smell. the cold is your control, if the hot sample smells buttery, you need more time on the yeast.
he really stressed temp control and aeration. temp differences of 3 degrees in the first few days of fermentation can really change the flavor, so if you don't have temp control, get it!
another interesting thing was mixing yeasts. start off fermentation with one yeast strain and when you get about halfway through, pitch your second strain and you will get something from both, whether it's super attenuation or a flavor. if it's a low gravity brew, just pitch them at the same time. i'm thinking about mixing saison and english yeast for some kind of mutant high attenuating pepper fruit beast.
last thing was the proper way to step up a starter. don't just cold crash and pitch fresh wort onto the starter cake. you get yeast growth from small beginning numbers of yeast so pull 100ml of starter wort and pitch that into the fresh starter wort, cold crashing the first starter and mixing them when done, you'll get vastly more yeast.
i picked out the overpitch brew but mixed up the under and the control. overpitch was very thin, under was bubblegummy and the control was more fruity. i was just glad to get one haha.
thanks again to everyone there. jason if you're reading this, i was the guy up front with the joker hat
also, sorry if it seems i'm stepping on your toes with this thread. i'm just stoked to talk about the new stuff i learned.
phattysbox said:Dude no worries!! You had some great questions and yes I agree with what you said. Next time I'll demonstrate more practical stuff. I was pressed for time and felt rushed towards the end.
BTW, you should be getting the powerppint file soon from BK homebrew.
J
Dude no worries!! You had some great questions and yes I agree with what you said. Next time I'll demonstrate more practical stuff. I was pressed for time and felt rushed towards the end.
BTW, you should be getting the powerppint file soon from BK homebrew.
J
Could this be shared with all of us nonpaying students?
Could this be shared with all of us nonpaying students?
The 100ml used for the second starter is non-crashed slurry, correct?
Correct.
However, if the starter is cold crashed and decanted then 1/10 of that volume should be used to inoculate the next starter. If that turns out be 140 mls then one would shake the decanted starter to get the flocs to break up and take 14 mls...
Got it, thanks. That makes sense. How anal retentive do we need to be about sanitation/sterilization? If I'm using clean, "star-sanned" glassware, is this going to lead to mutation?
-d
Contamination will not lead to mutation, only bad beer... Only stressful situations such as no O2 at beginning of fermentation or really high fermentation temps will cause mutations over time.
As for sanitizing, yes you should sanitize make everything clean as possible. Sterilization is best, but you either need a pressure cooker or autoclave for that.
Treat the starter as if it were a beer (for sanitation purposes)
J
A couple questions, since I find this topic interresting:
1. A stir bar will certainly keep the yeast in suspension and delay flocculation, but how does it force oxygen into suspension, to be available to the yeast? I had been led to believe the stir bar speed should be adjusted to make a dimple, not a vortex.
2. If you are repeating the experiment with oxygenation, how are you planning to meter the amount of oxygen in suspension? Certainly as a casual brewer, i just shake the P*&^ out of the fermenter after pitching, but as a lab experiment I assume you want eliminate differing oxygenation levels in the starter as a variable.
1. The surface area of a moving liquid under constant stirring is huge and gas exchange occurs at a very fast rate. No O2 is needed and tightly covered foil is sufficient. Either a dimple or a vortex - doesn't really matter. A vortex only increases gas exchange at a insignificant marginal rate more than a dimple.
2. A good question. I would have to get a oxygen regulator to monitor my flow rate. Since I don't have one, and funds are not available for one, I'll have to do my best with the oxygen system I have. I'll make sure to keep all samples the same - i.e. same amount of O2.
I think another important variable here is yeast selection. 1056 is not expressive at all and I might see better differences with a characterful english ale yeast.
1. The surface area of a moving liquid under constant stirring is huge and gas exchange occurs at a very fast rate. No O2 is needed and tightly covered foil is sufficient. Either a dimple or a vortex - doesn't really matter. A vortex only increases gas exchange at a insignificant marginal rate more than a dimple. QUOTE]
OK, I had assumed ( incorrectly, perhaps) that the pre pitch shaking had to be vigorous enough to force the air "into suspension" mechanically. From what you have said, a gentle swirling with a sanitized spoon for the same amount of time as the vigorous shaking would suffice. Have I missed something? Any idea what the effect of liquid temperature is on the o2 absorption rate? For instance, does o2 absorb faster in a warmer liquid?
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