Author Topic: fresh yeast quantity  (Read 2540 times)

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Offline upper crust

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fresh yeast quantity
« on: January 10, 2006, 12:52:58 PM »
hey guys... does anybody know if their is a formula or a way to figure out how much yeast to use per litter of water or per amount of flour?

-room temp (65F)

lets say one day I would like to do 6 hour rise another day a 15 hour rise etc..

how can I figure out how much yeast to use, depending on how long of a rise I want. without doing all kinds of trial and errors and wasting dough.


Offline chiguy

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Re: fresh yeast quantity
« Reply #1 on: January 10, 2006, 01:14:09 PM »
 Hi uppercrust,
 The fermention time is affectd by the amount of yeast being used, the kitchen temperature and just as important if not more important the finished dough temperature. I am aware that taking dough temperature is not common practice in italy with neo-dough. The guy's who are not taking dough temperature have been making pizza a long time and fermention time and temps are second nature to them. As for myself or anyone else that are not trained pizziolos, taking the dough temperature is good practice. It can help with understanding temperature and affects on fermention times. I have mentioned this before that an 18F rise in finished dough temperature can double yeast activity. The way i figure the problem is, once you fine tune procedure you can ditch everything from the thermometer to the measuring cups. The Neo style is one i have very limited experience with but the rules of fermention mentioned above still do apply.   Chiguy

Offline Pete-zza

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Re: fresh yeast quantity
« Reply #2 on: January 10, 2006, 01:27:35 PM »
upper crust,

Since you posted on the Neapolitan Style subject, I assume you would like to use fresh yeast for a Neapolitan style pizza.

If so, I would say that there is perhaps something out there that might help you. In fact, I recall reading about a relationship betwen yeast and time and have some notes on it somewhere in my notes file. I will try to find what I read.

I will mention, however, that it will be difficult to factor in temperature, amount of yeast, and time in one single equation or expression. That is too many simultaneous-occurring variables. Salt and other ingredients, and also water temperature, also play a role in fermentation/rise rates and times and can complicate matters.

I will see what I can find.

Peter


Offline Pete-zza

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Re: fresh yeast quantity
« Reply #3 on: January 10, 2006, 05:31:01 PM »
Chas,

I found what I was looking for--at http://www.dclyeast.co.uk/DCL_Main/main_tech/tech_dried.htm. The important part of the material at that site that relates to how much yeast (active dry yeast, or ADY) to use is the following, which I have excerpted:

The quantity needed is mainly determined by the recipe and process used and on local climatic conditions. As a guide, when processing a dough at 27C (80F) the quantity in grams of Active Dried Yeast required per 100kg of flour is indicated approximately by dividing a factor 1360 by the number of hours of bulk fermentation.

It takes a little work to convert the above to your situation, but let’s give it a try. For purposes of what follows, I will assume that you plan to use 1 kilogram (1000 grams, or 2.2 pounds) of flour, and that you would like to use compressed (cake) yeast and a room temperature of 65 degrees F and a 5 hour fermentation.

Based on the foregoing assumptions, the amount of ADY that would be needed for 1 kilogram of flour would be 1360/(5 x 100), or 2.72 grams. Since the above excerpt is based on ADY, to convert to cake yeast, we have to multiply 2.72 grams by 2. That gives us 5.44 grams. To convert that quantity to ounces, we divide it by 28.35, which gives us 0.1918871 ounces. From this point forward, I will give you the exact numbers in case you want to follow on your own calculator.

The above excerpt is also based on a fermentation temperature of 80 degrees F. To convert from that temperature to 65 degrees F, perhaps the easiest way is to adjust the amount of cake yeast. As chiguy has mentioned, for every 18 degrees increase in dough temperature, the rate of fermentation doubles. The number I usually use is 15 degrees, which is what General Mills uses, and I will use it here simply because it makes the math easier, especially since the difference between 65 degrees and 80 degrees happens to work out to exactly 15 degrees. To equate the two situations, if we double the amount of yeast, we get 0.3837742 ounces. Since one of those little cubes of fresh yeast found in the supermarket weighs 0.6 ounces, 0.3837742 ounces represents about 5/8 of one of such cubes. That sounds plausible to me.

If we use your 15-hour fermentation time example, you can go through the same exercise as above, or, since 15 hours is 3 times 5 hours, you can simply take 1/3 of 0.3837742, or 0.1279247 ounces of cake yeast. That comes to about 1/5 of one of the small supermarket cubes of cake yeast. That also seems plausible to me.

To simplify the math further, I have converted all of the above math to a simple expression that will save you a lot of time. Just divide 1.9188712 by T, Where T is the bulk fermentation time. That will give you the ounces of cake yeast you need for the fermentation time T. If you want to know what fraction of one of those little cubes of cake yeast that represents, you simply divide the results from using the expression 1/9188712/T by 0.6. Keep in mind, however, that this expression applies only to using 1 kilogram of flour, cake yeast, and a 65-degree room temperature fermentation. If you change any one or more of these parameters, the expression has to be redone. I think I gave you enough of the math and methodology to allow you to redo the expression yourself, but if you need help, let me know.

I have no idea how well the above expression will work in your real life situation. The final calculation is a guide only and there are too many variables at work that can alter the outcome, and the scaling process I went through may introduce its own effects. The above expression eliminates some of the variables but there are others at work also. For example, for Neapolitan style pizza dough, salt is often used as a regulator of the fermentation process, and water temperature can also be used to alter the fermentation process. Even changing the hydration can affect the rate of fermentation. Neapolitan doughs quite often use a lot of salt, in many cases from about 2.5-3% (by weight of flour). This can slow down the normal rate of fermentation. So you may want to increase the calculated yeast quantity a bit since I suspect that the material excerpted above does not contemplate such high amounts of salt. You might also use a water temperature to provide a finished dough temperature of around 80 degrees F. Beyond that, you will have to do some experimentation to get the dough exactly as you want. Like it or not, experimentation is inevitable.

Please let us know if you decide to proceed based on the above and, in particular, what results you get.

Peter

Offline upper crust

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Re: fresh yeast quantity
« Reply #4 on: January 10, 2006, 06:16:18 PM »
hey guys thanks so much for the input. here is a little more info.

1.7Kg of flour
1L of water
50G of salt
10G of yeast for a 8 hour rise at a room temp of 65F

I make the dough come off the hook @ 75F

-basically what I am trying to figure out is, when I make a really big batch of dough lets say 30.6Kg of flour
18Kg of water
900G of salt
?G of fresh yeast
and I make it come off the hook @ 75F, the room temp is 65F and I want it to rest for 8 hours.
-How much fresh yeast would I need? I know you would think just multiply 10G of yeast by 18Kg of water and then you'll have the answer but thats not the case.
« Last Edit: January 10, 2006, 08:16:37 PM by upper crust »

Offline Pete-zza

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Re: fresh yeast quantity
« Reply #5 on: January 10, 2006, 07:31:21 PM »
Chas,

I'm not sure what you are trying to say, but the relationship I previously discussed is not between water and yeast, but rather flour and yeast.

Let's take your first formulation and work on that and then we can look at your second formulation.

If you want to use 1.7 kg. of flour, cake yeast, a room temperature of 65 degrees F, and an 8-hour fermentation time, then, assuming that the prior methodology is correct, then 1360/8 equals 170, and the amount of ADY you would need is 170 x (1.7/100), or 2.89 g. For cake yeast, this would convert to 2 x 2.89, or 5.78 g. Using 65 degrees F, we double the amount of yeast to 11.56 g. That's a bit more than your formulation but it is in the ballpark.

Examining your second formulation, which calls for 18 times the flour of the first formulation, the amount of yeast you would need would be 18 times the amount of yeast in the first formulation, or 18 x 11.56 = 208.08 grams. If you work through the math from the beginning using 30.6 kg., you will confirm the 208.08 number.

FYI, the baker's percents for your first formulation is as follows, based on my calculations:

100%, Flour, 1.7 kg.
58.8%, Water, 1 kg.
2.94%, Salt, 50 g.
0.68%, Cake yeast, 11.56 g.

The corresponding numbers for the second formulation, but not the baker's percents (which remain the same), would be 18 times larger.

Given the amount of salt, the calculated amount of cake yeast seems reasonable to me, and your finished dough temperature of 75 degrees F should help keep the rate of fermentation within an acceptable range. However, the only way to really tell for sure is to make some dough based on the numbers. You might scale down the first formulation for test purposes so that you don't end up wasting the ingredients if the results turn out not to be what you want.

Peter

Offline sebdesn

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Re: fresh yeast quantity
« Reply #6 on: January 10, 2006, 10:36:47 PM »
Pete, To come up with that is truly awesome!

I wonder if all the effort with yeast timing/amount is relevant to pizza...
I bake lotsa bread, both with commercial yeast and natural. There, timing is everything.  Since the mechanics of pizza seems to be  oven spring from the dissolved co2/air ,and alcohol in the dough, The time ,as long as it "enough",  to achieve that, is all that is needed...Please  don't take this as being a smart azz,but hopefully a legitimate question/observation..
Bud

Offline Pete-zza

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Re: fresh yeast quantity
« Reply #7 on: January 11, 2006, 11:03:58 AM »
Bud,

That’s a fair observation and comment. And if we were talking about a dough other than a Neapolitan dough, such as a cold fermented dough, I might agree--at least in part--with your thesis. But not with respect to a Neapolitan dough. What upper crust is trying to do is to make an authentic Neapolitan dough—just as it would be made in Naples. Once I saw the formulation he posted and the question he posed, I knew almost immediately what he was trying to do, and the premise behind his question on the amount of yeast to use.

To make a typical Neapolitan dough as it would be made in Naples entails taking several important steps that are pretty much unique to Neapolitan doughs, including the following: 1) selecting and using a 00 flour, such as one of the several Caputo 00 flours, based on the desired fermentation time (or “window”); 2) using fresh yeast (or, less frequently, a preferment/starter); 3) using only room temperature fermentation, preferably within a controlled range of 64.4-68 degree F; 4) controlling the finished dough temperature; and 5) using a controlled amount of salt (usually sea salt at between 2.5-3% by weight of flour). All of these aspects, along with the hydration levels selected, have to be kept in proper balance in order to achieve optimal results. To this end, it is not unusual for Neapolitan pizzaioli to adjust the quantities of flour and salt, the hydration levels, and the amount of yeast in order to control the fermentation process. Quite often this is done to compensate for seasonal temperature changes, but it might also be done for dough management purposes. Using too much or too little salt or yeast, or too high a room temperature, or too high a finished dough temperature, can lead to less than satisfactory dough performance. The dough has to stay within the "window" to produce the best results and to allow the pizzaiolo to remain in business in a highly competitive business environment.

Based on my experience, it is far easier to make a cold fermented dough using refrigeration because refrigeration provides a greater measure of control over the dough management process than is present with authentic Neapolitan doughs where everything takes place at room temperature and where the doughs have to be used within the window designed into the dough by all of the measures discussed above, including the amount of yeast used. Hence, upper crust’s question about the amount of yeast to use is well founded in the context of the formulation he is planning to use and the objective he is trying to achieve—to make the best and most authentic Neapolitan dough/pizza possible. As for myself, I enjoyed the mathematical exercise and I would have gone through it any event, even if it was only to satisfy my own curiosity and to flex my brain muscles.

Peter

Offline chiguy

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Re: fresh yeast quantity
« Reply #8 on: January 11, 2006, 11:40:06 AM »
 Hi Sebdesn & Peter,
 What you said is absolutly correct,  a dough is ready when its' ready. On the other hand, I feel that understanding the rules that govern fermentation times are important in addressing problems that can occur during the process. Whether or not you strictly follow the rules is up to you, but knowing them can only help. They would definetly be important for upper crust, who is trying to achieve optimum fermention at a set time(6 & 15hours).

                                                                                                                   Chiguy       
                         

Offline upper crust

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Re: fresh yeast quantity
« Reply #9 on: January 11, 2006, 05:04:39 PM »
gentlemen I would like to thank you all for helping me out.

 ;)