Author Topic: Fresh yeast  (Read 7242 times)

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Offline norma427

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Re: Fresh yeast
« Reply #20 on: December 22, 2011, 12:02:45 AM »
Norma, I am sure there are members who will disagree with me, but you can propagate that CY in a starter like form.  This way you can have access to the same organisms whenever you need them.  I have been doing this for awhile now with seemingly consistent results.  All you have to do is to make a 50/50 mixture of flour and water and then add your CY.  Maintain it like you would a starter and the same yeast organisms should just replicate themselves.  By doing this, you don't have to keep buying fresh yeast.  

That or divide the block into multiple pieces, double wrap, vacuum seal, and freeze.  CY will last for a very long time in the freezer.

Chau

Chau,

I am always interested in your experiments or what you think.  I didnít know that CY can be propagated in a starter like form.  I never remembered you posting about that.  I would like to have access to the same organisms whenever I want to use them.  I will start an experiment using your methods and see what happens.  It would be great if I didnít have to buy CY because most of the time I canít find it in my area. I wonder if since some yeasts are fed molasses when they are started if molasses could be added to help propagate the yeast better.  

I do have some frozen cake yeast I have been recently using, but wonder how long it will last frozen.

Thanks!

Norma
« Last Edit: December 22, 2011, 12:04:34 AM by norma427 »
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Offline Pete-zza

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Re: Fresh yeast
« Reply #21 on: December 22, 2011, 07:49:22 AM »
Now that is interesting. The article states that different strains of S. cerevisiae are used to make the different types of yeast. I've never seen that in print before. Have you seen this written any place else?

http://www.cooksillustrated.com/tastetests/overview.asp?docid=9814

Craig,

I have researched and written on this subject (at a fairly elementary level) several times over the last several years. In fact, when I did an Advanced forum search this morning using my forum name and the terms yeast and strain, I got a bit over a page of hits. A lot of what I have written is repetitive, as the same questions on yeast would pop up from time to time. But I first became aware of the strain issue several years ago after reading an article, possibly one by Tom Lehmann, that said that IDY and ADY were different strains (and with different particle geometry also). And then there was a period where I had several exchanges by email and telephone with yeast producer like Fleischmann's and Red Star/SAF where I tried to find out whether the retail brands of their yeast products sold to mostly home bakers (like the Rapid Rise and similar fast-rise yeast products) were identical to those sold to professional bakers, which many of our members were using in the one- and two-pound bags. Getting answers to these simple questions was like pulling teeth and, to this day I am not absolutely certain, but the impression I came away with is that the yeast strains of the retail yeast products were not identical to those at the professional baker level but that any performance differences were minor and of no concern.

As an aside, from my experience dealing with yeast producers, I came to the conclusion that it is best to try to speak with someone on the foodservice side of the business where you are far more likely to be able to speak with a technical person familiar with the technical aspects of their yeast products. On the retail side, you get people who are more used to dealing with home consumers with the most basic of questions.

I think a good article to read on this subject, as well as other related topics, is the one at http://www.pizzamaking.com/forum/index.php/topic,8912.0.html. What I found interesting is the statement at the end of the article where it says that it can take up to ten years to develop a new yeast from strain to commercial product.

Peter

Offline DNA Dan

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Re: Fresh yeast
« Reply #22 on: January 06, 2012, 01:57:31 AM »
Aren't there more dead cells per gram of fresh yeast than for the pelletized versions? Performance aside, could this be adding a perceptible flavor that the pelletized form doesn't have?
« Last Edit: January 06, 2012, 01:59:10 AM by DNA Dan »

Offline Pete-zza

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Re: Fresh yeast
« Reply #23 on: January 07, 2012, 08:37:37 AM »
Aren't there more dead cells per gram of fresh yeast than for the pelletized versions? Performance aside, could this be adding a perceptible flavor that the pelletized form doesn't have?

Dan,

To the best of my knowledge, fresh yeast is about 70% water and all of the cells are live cells. See, for example, the quoted material in Reply 8 at http://www.pizzamaking.com/forum/index.php/topic,14060.msg141140/topicseen.html#msg141140. It is possible to destroy some of such cells by freezing the yeast, and especially if the freezing is done slowly, as in a static freezer, and in such a case one can expect the release of glutathione, which is an amino acid component of the dead cells. Otherwise, with the recommended use of the fresh yeast one should get good gassing power.

I have heard of using large amounts of dry yeast to get more crust flavor, in most cases because many professionals have gone to dry forms of yeast, but I recall that according to Professor Raymond Calvel in his book The Taste of Bread, you need at least 2.5% fresh yeast to taste it in a finished bread. He did not give a corresponding percent for ADY or IDY. 

Peter

Offline dellavecchia

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Re: Fresh yeast
« Reply #24 on: January 07, 2012, 09:36:15 AM »

but I recall that according to Professor Raymond Calvel in his book The Taste of Bread, you need at least 2.5% fresh yeast to taste it in a finished bread. He did not give a corresponding percent for ADY or IDY. 


Peter - Does this imply tasting the yeast itself, or the by products?

John

Offline Pete-zza

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Re: Fresh yeast
« Reply #25 on: January 07, 2012, 10:11:38 AM »
Peter - Does this imply tasting the yeast itself, or the by products?

John

John,

This is what Professor Calvel says in the book about fresh yeast ("baker's yeast"), at page 19-20:

This commercially produced yeast (Figure 2-2) is generally of uniformly good quality. The taste of bread made through the use of this "biological" baker's yeast is relatively low in acid and is dominated by the taste and aroma derived from wheat flour. These elements are combined with flavor components produced by alcoholic fermentation of the dough and as a result of the baking process. In French bread, the taste of yeast is not discernible until the usage level reaches 2.5%. Beyond that level its presence becomes more and more noticeable as the usage level increases. Without being disagreeable in itself, this is an atypical taste that seems undesirable in bread.

I first became acutely aware of the use of a lot of yeast for crust flavoring purposes when I played around with very low hydration doughs (around 35% hydration) for cracker style doughs/pizzas. Those doughs fermented very slowly so it took a long time to develop all of the byproducts of fermentation that contribute to final crust color, flavor, taste, aroma and texture. So, the easy way out was to just use more yeast. And, since the skins were rolled out, usually with commercial rollers/sheeters (or by rolling pin or equivalent in a home setting), and then docked, dough volume was not an issue since these measures forced most of the gases out of the skins. I also learned that professionals who make cracker style doughs seem to use short periods of fermentation, whether at room temperature (usually for same day use) or in a cooler (typically for a day). So, high yeast usage makes sense as a way of getting more crust flavor.

Peter

Offline Jackie Tran

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Re: Fresh yeast
« Reply #26 on: January 07, 2012, 10:50:29 AM »
Peter, I recently made a 3 hour emergency pie using high amounts of CY, well high for me anyway.  I didn't post the exact amount but it was no higher than 1.5%, I'll have to check my notes again.  But I did note a surprisingly yeasty taste to the crust.   It was also aged CY and not fresh that I used.

Reply #15

http://www.pizzamaking.com/forum/index.php?topic=15956.0

Offline Pete-zza

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Re: Fresh yeast
« Reply #27 on: January 07, 2012, 12:50:54 PM »
Chau,

One of the first times I tried to make an emergency dough was with Tom Lehmann's NY style dough formulation. I was tapped into such a version by something that I read by Tom over at the PMQ Think Tank (unfortunately, the link was in an older version of the PMQTT forum and is no longer accessible). However, I made reference to the amounts of yeast Tom said to use to make a short-time emergency dough, at Reply 407 at http://www.pizzamaking.com/forum/index.php/topic,576.msg27251.html#msg27251. You will note that the recommended amount was 2% for fresh yeast. Since it has been a very long time since I have been able to find fresh yeast in the markets near me, I have pretty much used the 2% figure when converting from fresh yeast to ADY or IDY.

I note in the example you referenced at Reply 15 http://www.pizzamaking.com/forum/index.php/topic,15956.msg156743.html#msg156743 that you used ingredients other than just flour, water, salt and yeast, namely, oil and dry milk powder, as well as old cake yeast. Dry milk powder includes its own flavor contributors, including lactose and other "sugars" (about 52% by weight) as well as small amounts of fats and calcium and other minerals that can impart flavor to products into which the dry milk is incorporated. The lactose itself is on the low end of the scale of sweetness compared with table sugar (it is about 16% as sweet as table sugar), but when I have used dry dairy products, including whey and dairy blends, in pizza doughs I can detect that they are there, typically with a dairy note and mild sweetness. The only way to rule out the contribution of dry milk is to omit it, and use just flour, water, salt and the cake yeast at 2.5%, and preferably fresh. Using old cake yeast might also make an interesting experiment to see if old yeast imparts a flavor that new cake yeast does not.

Peter

Offline Jackie Tran

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Re: Fresh yeast
« Reply #28 on: January 07, 2012, 04:07:57 PM »
Peter you are right, dry milk and oil can definitely add to the flavor profile, but not in a yeasty manner.  I have used very similar recipes before with a longer fermentation period and did not note the yeasty flavor.

Next time I get some fresh CY, i'll remake this 3hour dough and see if I notice the yeasty flavor again.  I have never used more than 1.5% CY so at 2.5%, the dough maybe ready in an hour or so.    :-D

UPDATE:  My mistake Peter.  My memory is faulty.  I went back and found my notes, it was 2% CY, when I thought it was ~1.5% earlier.  Definately yeasty taste at 2% old CY. 
« Last Edit: January 07, 2012, 09:51:51 PM by Jackie Tran »


 

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