Need help understanding yeast

[shopkins1994]

Hi Everyone,

I needed help understanding what is happening with a yeast experiment. In my experiment, I use all-purpose flour and baker's yeast because they are readily available, cheap, and easy to mix.

First experiment: 250 grams all-purpose flour, 200 grams water, 1/6 TEASPOON bakers yeast. Mix well and let sit in a close vessel for 12 hours. When I remove the lid, I can quite clearly smell the alcohol and other fumes, sometimes having to turn my head. The flour is very puffed up from the CO2.

Second experiment: 250 grams all-purpose flour, 200 grams water, 1 TABLESPOON yeast. Mix well and let sit in closed vessel for 1 hour. When I remove the lid, no smell at all other than flour. It is puffed up a lot from the CO2.

So my question is, when I use 48 times more yeast, the time for the alcohol and fumes to be produced is not reduced at all.

Does anyone know why this experiment is turning out as it is? I would expect more yeast equals quicker ferment.

Any insight or help you can provide is greatly appreciated.

 

[Hjandersen]

First experiment: 250 grams all-purpose flour, 200 grams water, 1/6 TEASPOON bakers yeast. Mix well and let sit in a close vessel for 12 hours. When I remove the lid, I can quite clearly smell the alcohol and other fumes, sometimes having to turn my head. The flour is very puffed up from the CO2.

Second experiment: 250 grams all-purpose flour, 200 grams water, 1 TABLESPOON yeast. Mix well and let sit in closed vessel for 1 hour. When I remove the lid, no smell at all other than flour. It is puffed up a lot from the CO2.

So my question is, when I use 48 times more yeast, the time for the alcohol and fumes to be produced is not reduced at all.

Does anyone know why this experiment is turning out as it is? I would expect more yeast equals quicker ferment.

Any insight or help you can provide is greatly appreciated.

The main factor would be whether or not oxygen is present. Yeast is a facultative anaerobe organism - capable of aerobic respiration if oxygen is present and fermentation if oxygen isn't available. In the second, short experiment the yeast is never forced to switch to fermentation and thus very little or no alcohol (and most other yeast-derived flavours) is formed.

 

[yeahfairly]

I am not a yeast expert but...... If I were guessing I would say that regardless of how much yeast you add to the all-purpose flour, there is a lag time in the fermentation process due to the required conversion of the starches in the flour that must take place before the yeast can start munching on them.

 

[shopkins1994]

The main factor would be whether or not oxygen is present. Yeast is a facultative anaerobe organism - capable of aerobic respiration if oxygen is present and fermentation if oxygen isn't available. In the second, short experiment the yeast is never forced to switch to fermentation and thus very little or no alcohol (and most other yeast-derived flavours) is formed.

I would think that the 1 tablespoon of yeast would consume all the oxygen relatively quickly? If I go your theory (which it may very well be correct, I don't know), if the 1/16 teaspoon yeast can consume it in 12 hours, shouldn't 48 times more yeast be able to do it very quickly?

 

[flars]

You may be trying to mash wheat, with no diastatic power, at to low of temperature, for conversion, if there were starches to convert. Bakers yeast works in bread because sugar is added for the yeast to use for the rising.

 

[duboman]

Welcome to the world of a severe over pitch as can also happen in brewing. If the massive amount of yeast consume everything available to them in a limited state they lose the ability to properly function and quit working.

Obviously this is an extremely basic explanation but in brewing, poor attenuation can occur for the exact same reason.

Think of it this way, if you send a crew of 50 people to perform the job that only requires 10 men, you wind up with a bunch of people standing around picking their a$$ with nothing to do and no resources available to them to do their job

 

[Hjandersen]

I would think that the 1 tablespoon of yeast would consume all the oxygen relatively quickly? If I go your theory (which it may very well be correct, I don't know), if the 1/16 teaspoon yeast can consume it in 12 hours, shouldn't 48 times more yeast be able to do it very quickly?

Nope - you're missing the basic fact that yeast divide - a yeast cell population in good conditions should exhibit logistic growth. Expect a doubling of the yeast cell count every 1-2 hours..

In other words, for the sake of easy calculations let's say you're adding 4 mill yeast cells for 12 hours and 200 mill for 1 hours - then:

Low yeast dose + long time: 12 hours => 12 divisions: 4^12 = 16,777,216 mill yeast cells
High yeast dose - short time: 1 hours => 0 divisions: 200^1 = 200 mill

In this scenario you'd be dealing with a fold difference of 83,000 in favour of the low yeast dose.

 

[shopkins1994]

Welcome to the world of a severe over pitch as can also happen in brewing. If the massive amount of yeast consume everything available to them in a limited state they lose the ability to properly function and quit working.

Obviously this is an extremely basic explanation but in brewing, poor attenuation can occur for the exact same reason.

Think of it this way, if you send a crew of 50 people to perform the job that only requires 10 men, you wind up with a bunch of people standing around picking their a$$ with nothing to do and no resources available to them to do their job

Duboman, it appears that over pitching doesn't limit the function. The yeast are clearly consuming sugar because they are releasing CO2 in huge amounts. The flour mixture with 1 tablespoon of yeast starts to rise almost immediately, compared to the 1/16 teaspoon where it doesn't. So the question is, if the yeast are releasing CO2 and clearly consuming sugars, where are all the byproducts at (i.e. aromas, alcohol, etc)?

 

[duboman]

Duboman, it appears that over pitching doesn't limit the function. The yeast are clearly consuming sugar because they are releasing CO2 in huge amounts. The flour mixture with 1 tablespoon of yeast starts to rise almost immediately, compared to the 1/16 teaspoon where it doesn't. So the question is, if the yeast are releasing CO2 and clearly consuming sugars, where are all the byproducts at (i.e. aromas, alcohol, etc)?

Sorry, that's not how I read your OP, you stated that while the first batch had the smell of alcohol and other fumes the second did not. If you had to turn your head away from the first batch you most likely got a huge whiff of co2 which can take your breath away and make you pass out, the second you stated this did not happen so I read that as being less efficient fermentation. While the yeast may have proofed/puffed up it clearly was not working the same way the smaller yeast pitch was. co2 is a byproduct of fermentation, not growth.

During the initial pitch the yeast are multiplying and once they go through the growth phase they begin fermentation, from what I am reading it appears that while both yeast pitches went through/are going through growth phase, the smaller pitch actually began to ferment and the larger pitch did not, hence my explanation.

If I am missing something perhaps you switched the amounts pitched in your OP and recorded observations are mixed?

 

[boydster]

Duboman, it appears that over pitching doesn't limit the function. The yeast are clearly consuming sugar because they are releasing CO2 in huge amounts. The flour mixture with 1 tablespoon of yeast starts to rise almost immediately, compared to the 1/16 teaspoon where it doesn't. So the question is, if the yeast are releasing CO2 and clearly consuming sugars, where are all the byproducts at (i.e. aromas, alcohol, etc)?

If the yeast is clearly consuming sugars and there is CO2 as you say, the answer is that you simply aren't detecting the byproducts even though they are there (except you are noticing one of the primary byproducts). When sugars are consumed, ethanol and CO2 are the byproducts, and you simply won't get large amounts of CO2 without producing some ethanol. More yeast growth will allow for more ester development, so perhaps that is the element that is lacking in your 1T group.

 

[shopkins1994]

Everyone, thank you so much for all the help. You have given me some ideas to go after. Right now I have both the 1/16tsp and 1TBL going at the same time to see what I get tomorrow morning.

Does anyone know what an ester smells like? Tough I know. When I think of what ethanol smells like, I think vodka.

 

[shopkins1994]

Well, the 1TBL experiment had risen and fallen and had much more of an odor than then 1/16tsp version. I actually coughed when I inhaled the 1TBL air.

 

[MattyIce]

From a lab standpoint, huffing fumes of chemical reactions is bad juju lol. Is there a way to measure alcohol despite all that flour?

 

[shopkins1994]

From a lab standpoint, huffing fumes of chemical reactions is bad juju lol. Is there a way to measure alcohol despite all that flour?

=D

I don't think so. Though I was going to try to suction the air out and pump it through my portable breathalyzer and see if that would give anything.

 

[Happywanderer]

The issue is that yeast in a dough starter (like a sour dough starter) is really a function of time.

This is from a sourdough starter FAQ.

My sourdough starter smells like alcohol. Is there a way to fix it?

When sourdough starter isn't fed often enough or feedings are skipped, it is common for an alcohol odor to develop. When a sourdough starter runs out of food, it will begin consuming discarded yeast as well as its own waste, leading to the odor. The best way to prevent this from happening is to feed the sourdough starter more often. How often a sourdough starter is fed is a function of the nature of the particular variety of starter, how active the starter is and room temperature, so it may take some adjustment and experimentation to find the best feeding schedule for your situation. Most sourdough starters do best being fed every 8 to 12 hours when not stored in the refrigerator. Some varieties such as brown rice sourdough starter may need to be fed more often (closer to every 4 hours).

To correct an existing alcohol odor problem, you can sweeten your starter by taking 8 ounces (1 cup) of your sourdough starter and mix it with 4 ounces (1/2 cup) of flour and 4 ounces (1/2 cup) of water. Stir thoroughly, then let the starter sit at room temperature until it's nice and bubbly before returning it to the refrigerator. This method is also useful for correcting an overly sour starter. If this method is not successful, contact us for further instructions.

 

[shopkins1994]

I think I am getting closer!

Last night I mixed up a 1TBL batch and a 1/16TSP batch. In both I added 2TBL of table sugar and 1/4TSP yeast energizer. This morning the 1/16TSP had no odor. The 1TBL had a STRONG odor. The strongest yet. I might have blacked out when I sniffed it. I am going to try more sugar tonight and see if the odor reduces.

 

[ABVIBUSRM]

Hi Everyone,

I needed help understanding what is happening with a yeast experiment. In my experiment, I use all-purpose flour and baker's yeast because they are readily available, cheap, and easy to mix.

First experiment: 250 grams all-purpose flour, 200 grams water, 1/6 TEASPOON bakers yeast. Mix well and let sit in a close vessel for 12 hours. When I remove the lid, I can quite clearly smell the alcohol and other fumes, sometimes having to turn my head. The flour is very puffed up from the CO2.

Second experiment: 250 grams all-purpose flour, 200 grams water, 1 TABLESPOON yeast. Mix well and let sit in closed vessel for 1 hour. When I remove the lid, no smell at all other than flour. It is puffed up a lot from the CO2.

So my question is, when I use 48 times more yeast, the time for the alcohol and fumes to be produced is not reduced at all.

Does anyone know why this experiment is turning out as it is? I would expect more yeast equals quicker ferment.

Any insight or help you can provide is greatly appreciated.

because when there is less yeast there is more growth= more metobolic activity= more smell

 

[shopkins1994]

because when there is less yeast there is more growth= more metobolic activity= more smell

It seems that the yeast running out of food is causing the smell.

 

[ABVIBUSRM]

Why are you experimenting with flour instead of wort? Just curious

 

[shopkins1994]

Flour is a lot easier and cheaper. It also rises so I can judge the CO2 without an airlock.

 

[ABVIBUSRM]

Flour is a lot easier and cheaper. It also rises so I can judge the CO2 without an airlock.

yeah but it does not have maltose in it..so the yeast will react different

 

[dyqik]

You may be trying to mash wheat, with no diastatic power, at to low of temperature, for conversion, if there were starches to convert. Bakers yeast works in bread because sugar is added for the yeast to use for the rising.

Baker's yeast works fine in bread without any added sugar. Most french bread and sourdough recipes don't use any sugar at all. Bread flour has some diastatic power, and can convert itself somewhat - enough to get a very good rise. Rising is usually more limited by the strength of the gluten matrix and it's ability to hold onto the CO2 bubbles. Kneading dough helps to break up the starch and release sugars as well as building the gluten matrix.

 

[ABVIBUSRM]

i just read the ingredients to APF and it does indeed have malted barley flour so there is some maltose but i still think its not the best medium for yeast experiments