[HoosierBrew]

I see it definitely as art in the inception stage - coming up with the mental picture of the beer's color, flavor profile, aroma, body. After that it's using scientific principles to your advantage. Thank goodness for that info. 

[S. cerevisiae]

On my lager starters, I did move to 1 liter starters with 7 ounces of DME to boost cell count but only because I had everything I needed for that.  So does this sound like underpitching?

No, this part does not sound like underpitching, but it does sound like a recipe for yeast stress.  Seven ounces of DME is equal to 198.5 grams of DME.  That amount of DME in a 1L solution is a 198.5 / 1000  * 100 = 19.6% solution weight by volume, which is equal to 19.6 Plato because 1ml of water weighs 1g.  A 19.6 Plato wort is a 1.081 wort.  That's a recipe for serious osmotic pressure induced stress and possible cell death.

Osmotic pressure is a concept that is thrown around in home brewing circles, but few home brewers actually know what it means.  Osmotic pressure is the result of liquids on opposite sides of a semi-permeable membrane having different solute levels (the primary solute in wort is sugar).  What happens is that water is drawn to the side of the semi-permeable membrane that contains the highest solute content, which is the wort in a high gravity starter or batch.  The loss of water inside of the cell results in the loss of something known as turgor pressure.  Turgor pressure is the internal pressure that pushes the cell plasma membrane up against the cell wall. Loss of turgor pressure results in wrinkling of the plasma membrane and shrinkage of the cell wall.  This morphological change results in nutrients not being able to enter and waste products not being able to exit the cell as freely as they would in a non-dehydrated cell.

The images shown below were cut out of a publication entitled "The Effects of Osmotic Pressure and Ethanol on Yeast Viability and Morphology" (http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.2003.tb00162.x/pdf).  I had the pleasure of exchanging e-mail with G.G. Stewart a couple of years ago when I inquired about two yeast strains that he deposited into the NCYC.  It is a rare treat to find a yeast culture deposit where the depositor is still with us.

Here's what happens when yeast cells are subjected to 20% w/v sorbitol (sugar alcohol):



Ethanol has the same type of effect on yeast cells because ethanol is hygroscopic.  In essence, yeast cells stop fermenting because they become dehydrated to the point where the loss of turgor pressure prevents them from taking in nutrients and expelling waste products.

Here's what happens when yeast cells are subjected to 10% w/v ethanol:

[Village Taphouse]

On my lager starters, I did move to 1 liter starters with 7 ounces of DME to boost cell count but only because I had everything I needed for that.  So does this sound like underpitching?

No, this part does not sound like underpitching, but it does sound like a recipe for yeast stress.  Seven ounces of DME is equal to 198.5 grams of DME.  That amount of DME in a 1L solution is a 198.5 / 1000  * 100 = 19.6% solution weight by volume, which is equal to 19.6 Plato because 1ml of water weighs 1g.  A 19.6 Plato wort is a 1.081 wort.  That's a recipe for serious osmotic pressure induced stress and possible cell death.

Osmotic pressure is a concept that is thrown around in home brewing circles, but few home brewers actually know what it means.  Osmotic pressure is the result of liquids on opposite sides of a semi-permeable membrane having different solute levels (the primary solute in wort is sugar).  What happens is that water is drawn to the side of the semi-permeable membrane that contains the highest solute content, which is the wort in a high gravity starter or batch.  The loss of water inside of the cell results in the loss of something known as turgor pressure.  Turgor pressure is the internal pressure that pushes the cell plasma membrane up against the cell wall. Loss of turgor pressure results in wrinkling of the plasma membrane and shrinkage of the cell wall.  This morphological change results in nutrients not being able to enter and waste products being able to exit the cell as freely as they would in a non-dehydrated cell.

The images shown below were cut out of a publication entitled "The Effects of Osmotic Pressure and Ethanol on Yeast Viability and Morphology" (http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.2003.tb00162.x/pdf).  I had the pleasure of exchanging e-mail with G.G. Stewart a couple of years ago when I inquired about two yeast strains that he deposited into the NCYC.  It is a rare treat to find a yeast culture deposit where the depositor is still with us.

Here's what happens when yeast cells are subjected to 20% w/v sorbitol (sugar alcohol):



Ethanol has the same type of effect on yeast cells because ethanol is hygroscopic.  In essence, yeast cells stop fermenting because they become dehydrated to the point where the loss of turgor pressure prevents them from taking in nutrients and expelling waste products.

Here's what happens when yeast cells are subjected to 10% w/v ethanol:

Mark, wow... thanks for that.  I just went down to my "brew bunker" to check the sizes of the two flasks I have.  I was wrong.  I have been using 7 ounces of DME in a *TWO*-liter starter flask, not a 1-liter.  This all started because I had a 1-liter flask and a bud of mine who had numerous extra flasks gifted me one of his 2-liters.  I wanted to get away from the "bumping-up" of lager starters so numerous people suggested 7 ounces of DME in 2-liters, use some O2, get it on the stirplate, get it to high-krauesen, chill, decant, etc. and I have made several lagers this way in the past 8 months or so with very good results.  Do you have an opinion on the best amount of DME to use in a 2-liter starter or the best OG for a starter?  Also, do you have an opinion on using pure O2 through a stone in a starter?  Many brewers have said that they think it's a waste of O2 but I do it on every starter just like I oxygenate 5+ gallons of wort.  Thanks again for the response... good stuff.

[S. cerevisiae]

I will give you and anyone who is interested simplifying his/her starter preparation process some advice, and, that is, do not mix units of measurement.  Our modified English-based units of measurement are inferior to the metric system when culturing or performing any other laboratory work.  For example, weight-by-volume and weight-by-weight are not equal when using our units of measure because one U.S. fluid ounce weighs more than one U.S. dry ounce.  Specific gravity is also a flawed unit of measure because it is affected by temperature, which is why professional brewers use degrees Plato.  Degrees Plato measures sugar concentration weight-by-weight.

Making a starter of any gravity is a trivial process when using the metric system. Weight-by-volume (w/v) and weight-by-weight (w/w) are equivalent units of measure when the solvent is water when using the metric system because one milliliter of water weighs one gram.  Making a starter of any gravity is as simple as looking up degrees Plato for the gravity desired, dividing that number by 100, and multiplying the result by 1,000 in order to obtain the number of grams of DME per liter needed to prepare the solution.  For example, a 10% w/v solution is a 10P solution, which is a 1.040 solution at 60F (most hydrometers are calibrated at 60F).  A 10% w/v solution contains 10 / 100 * 1000  = 100 grams of DME per liter of solution.  A 5% w/v solution is a 5P solution, which is a 1.020 solution. A 5% w/v solution contains 5  / 100 * 1000 = 50 grams of DME per liter of solution.  The relationship between degrees Plato and specific gravity is not linear above 12.5P, but conversion is simple using a look-up table.  For example, a 15% w/v solution is not a 1.060 solution.  It is a 1.061 solution. 

[klickitat jim]

I will give you and anyone who is interested simplifying his/her starter preparation process some advice, and, that is, do not mix units of measurement.  Our modified English-based units of measurement are inferior to the metric system when culturing or performing any other laboratory work.  For example, weight-by-volume and weight-by-weight are not equal when using our units of measure because one U.S. fluid ounce weighs more than one U.S. dry ounce.  Specific gravity is also a flawed unit of measure because it is affected by temperature, which is why professional brewers use degrees Plato.  Degrees Plato measures sugar concentration weight-by-weight.

Making a starter of any gravity is a trivial process when using the metric system. Weight-by-volume (w/v) and weight-by-weight (w/w) are equivalent units of measure when the solvent is water when using the metric system because one milliliter of water weighs one gram.  Making a starter of any gravity is as simple as looking up degrees Plato for the gravity desired, dividing that number by 100, and multiplying the result by 1,000 in order to obtain the number of grams of DME per liter needed to prepare the solution.  For example, a 10% w/v solution is a 10P solution, which is a 1.040 solution at 60F (most hydrometers are calibrated at 60F).  A 10% w/v solution contains 10 / 100 * 1000  = 100 grams of DME per liter of solution.  A 5% w/v solution is a 5P solution, which is a 1.020 solution. A 5% w/v solution contains 5  / 100 * 1000 = 50 grams of DME per liter of solution.  The relationship between degrees Plato and specific gravity is not linear above 12.5P, but conversion is simple using a look-up table.  For example, a 15% w/v solution is not a 1.060 solution.  It is a 1.061 solution.

Ok, but what Plato is best for a starter? I've been using 1.030 for starters

[S. cerevisiae]

Ok, but what Plato is best for a starter? I've been using 1.030 for starters

You are asking for absolutes where no absolute exists.  A 1.030 starter is a 7.5P, or 7.5% w/v starter.  I have used 5% (1.020), 7.5% (1.030), and 10% (1.040) starters. I currently only use 5% and 10% media for starters.  I use 5% media for first-level starters when propagating from slant, attempting to revive bottle sediment, and starting old commercial cultures.  I use 10% media for second-level starters when starting from slant and propagating commercial yeast cultures that are less than four months old.

DeClerck stated that 1 gram of extract contains enough carbon to grow 1 billion cells. Other scientists have bumped that number up to around 1.5 billion cells per gram (both growth rates are bounded by culture volume).  Given the room to grow and enough dissolved O₂ to support cell heath, we can expect to be able to grow between 75 and 112.5 billion cells with a 7.5% (1.030) 1L starter. A 1L 10% starter contains enough carbon to grow between 100 and 150 billion cells, which pretty much ensures that there is enough carbon to approach, it not reach maximum cell density with a young White Labs vial.  I suspect that a well-swollen Wyeast smack pack will reach maximum cell density due to the fact that it has a built-in first-level starter.  In the grand scheme of things, the difference between 75 billion and 100 billion cells is insignificant due to the fact that yeast biomass grows exponentially. We have to get to a point where the difference in cell counts is a couple of multiples before we see a significant difference in performance.

[klickitat jim]

Ok, but what Plato is best for a starter? I've been using 1.030 for starters

You are asking for absolutes where no absolute exists.  A 1.030 starter is a 7.5P, or 7.5% w/v starter.  I have used 5% (1.020), 7.5% (1.030), and 10% (1.040) starters. I currently only use 5% and 10% media for starters.  I use 5% media for first-level starters when propagating from slant, attempting to revive bottle sediment, and starting old commercial cultures.  I use 10% media for second-level starters when starting from slant and propagating commercial yeast cultures that are less than four months old.

DeClerk stated that 1 gram of extract contains enough carbon to grow 1 billion cells. Other scientists have bumped that number up to around 1.5 billion cells per gram (both growth rates are bounded by culture volume).  Given the room to grow and enough dissolved O₂ to support cell heath, we can expect to be able to grow between 75 and 112.5 billion cells with a 7.5% (1.030) 1L starter. A 1L 10% starter contains enough carbon to grow between 100 and 150 billion cells, which pretty much ensures that there is enough carbon to approach, it not reach maximum cell density with a young White Labs vial.  I suspect that a well-swollen Wyeast smack pack will reach maximum cell density due to the fact that it has a built-in first-level starter.  In the grand scheme of things, the difference between 75 billion and 100 billion cells is insignificant due to the fact that yeast biomass grows exponentially. We have to get to a point where the difference in cell counts is a couple of multiples before we see a significant difference in performance.

I'll stick with my 1.030 then. Thanks

[Village Taphouse]

Wow I'm I glad we have Mark here.  Yeast is by far the most mysterious part of brewing for me because I have no idea what the health of the yeast is like, how much of the content is dead cells, how many cells there are and what they may be needing and/or lacking.  I also realize that the right approach to using yeast produces better beer so I'm all for happy & "ready" yeast.  Cheers.

[Footballandhops]

I like to pitch yeast into wort after I cool it down and transfer it to my fermenter.

That is how I use my yeast

[Hooper]

I've decided putting my yeast on a stir plate is akin to putting cattle on a feed lot or chickens in a small pen. It also may be making them dizzy. So...I put the not quite cooled starter wort on the stir plate to aerate until it reaches ambient temperature....then I turn the stir plate off and add the "free range" yeast. I do not decant...I add it all to the fermenter the next day or two.

[RPIScotty]

Does anyone here play guitar? I frequent the various Les Paul guitar forums around the internet, and being that I am an electrical engineer, I tend to get involved in discussions concerning electrical components in guitar circuits. One in particular that gets a considerable amount of attention and attracts a considerable amount of debate is the use of different types of capacitors (with different dielectric compositions) in passive tone controls circuits. Often there are spirited debates between engineers like myself and the various die hard guitar players (pros and hobbyists) over whether these different compositions can affect the tone of the instrument, specifically the high frequency content of the output signal.

Long story short, there are always going to be differing opinions based on professional, academic and empirical experience in brewing, as well as many other fields and hobbies. I always found it is important to have an open mind, to challenge your assumptions and make decisions based on both experience and science.

These threads concerning the "Shaken not Stirred" method and the offshoot conversations that have sprung up about it are extremely interesting. Its enjoyable to see people questioning their methods, challenging themselves to step outside of their experiences and doing it all in a civil, respectable manner.

There is a reason why this is the most evolved and enjoyable of all the brewing forums.

[beersk]

Does anyone here play guitar? I frequent the various Les Paul guitar forums around the internet, and being that I am an electrical engineer, I tend to get involved in discussions concerning electrical components in guitar circuits. One in particular that gets a considerable amount of attention and attracts a considerable amount of debate is the use of different types of capacitors (with different dielectric compositions) in passive tone controls circuits. Often there are spirited debates between engineers like myself and the various die hard guitar players (pros and hobbyists) over whether these different compositions can affect the tone of the instrument, specifically the high frequency content of the output signal.

Long story short, there are always going to be differing opinions based on professional, academic and empirical experience in brewing, as well as many other fields and hobbies. I always found it is important to have an open mind, to challenge your assumptions and make decisions based on both experience and science.

These threads concerning the "Shaken not Stirred" method and the offshoot conversations that have sprung up about it are extremely interesting. Its enjoyable to see people questioning their methods, challenging themselves to step outside of their experiences and doing it all in a civil, respectable manner.

There is a reason why this is the most evolved and enjoyable of all the brewing forums.

Opinions are just that - opinions. Science is science - it is there to prove, not to opine. Any good scientist accepts results with skepticism, that's why empirical data must be collected. That's why we have awesome people like Mark with microscopes and all that fancy sh*t that spread their knowledge to us common folk who don't have the ambition to study in such detail and access to such equipment.

[Village Taphouse]

These threads concerning the "Shaken not Stirred" method and the offshoot conversations that have sprung up about it are extremely interesting. Its enjoyable to see people questioning their methods, challenging themselves to step outside of their experiences and doing it all in a civil, respectable manner.

There is a reason why this is the most evolved and enjoyable of all the brewing forums.

Well said and I agree 100%.

[RPIScotty]

Long story short, there are always going to be differing opinions based on professional, academic and empirical experience in brewing, as well as many other fields and hobbies. I always found it is important to have an open mind, to challenge your assumptions and make decisions based on both experience and science.

Opinions are just that - opinions. Science is science - it is there to prove, not to opine. Any good scientist accepts results with skepticism, that's why empirical data must be collected. That's why we have awesome people like Mark with microscopes and all that fancy sh*t that spread their knowledge to us common folk who don't have the ambition to study in such detail and access to such equipment.

Just to be clear, I agree with you 100%. I didn't mean to give the impression that I am for arguing opinion in the face of science. I used my example to illustrate how civil this forum is compared to many others of all varieties.

The great thing about this forum is people's willingness to adjust and alter their opinions based on empirical evidence. That is truly a rare thing in some of these dogmatic communities.

Sorry to derail the thread. Continue this conversation please! One of the best I've read for sure.

[Village Taphouse]

Again, agree with all of the above.  I like Beersk's comment about our brewing superheroes doing the dirty work for us mortals so we can all benefit by making better beer.  I try to go out of my way to share what I have learned but none of my information could be called scientific or even carefully collected.  I am a "by the numbers" brewer for the most part.  If I hear of someone doing something that seems to have a benefit that lines up nicely with the way I do things, I try it.  If for some reason the new trick has to do with equipment that I don't use or it addresses a problem I don't seem to have, I just put it in my back pocket for later.  On the topic of dogmatic communities, I assume we have all concluded that many people conduct themselves different online than they would IRL because there are no consequences.  This goes for all online activity, not just brewing.  But our hobby also has SO many boogeymen and "learned guidelines" that end up becoming arguments.  The only way to slash the boogeymen is to prove that they don't exist and try something a little off-the-map to see if it works.  Cheers.