The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Proofing fresh yeast

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msova's picture
msova

Proofing fresh yeast

So how much foaminess should I get when proofing fresh yeast (Or any yeast for thy matter). Also, if I pull the fresh yeast out of the fridge, seems I should let it attain room temperature even if using warm water right? (Theory being that the cold yeast cools off the water and hence the lackluster foaming). 

Mini Oven's picture
Mini Oven

flour, squish yeast & flour with your fingers to break it up and not worry about it.  

If it looks good and smells good it will work just fine.  

Kitchen Barbarian's picture
Kitchen Barbarian

Here's a pictorial account of what "until the yeast foams" looks like.

If you're not getting that, the yeast is probably kaput.  Be sure you put some sugar in the water with the yeast.  I think about a tsp to 1/4cup of warm water?  Or is that 1/2 tsp in 1/4 c of warm water?  Something like that.

And the temp of the yeast is pretty inconsequential - its not going to lower the temp of the water enough to matter even if you take the yeast directly out of the freezer.

EDIT:  Ooops, I see you're talking about fresh yeast. Here's a tutorial on proofing fresh yeast.  Fresh yeast is fragile enough that I wouldn't even consider using it without proofing first, due to the high chances of getting an old/bad batch and it not working.  I'd rather it poop out on the counter in a little sugar water than in 2 lbs of supposed-to-be-dough that won't rise, LOL!

Personally I find it (fresh yeast) to be way more trouble than its worth.  I find no difference in flavor between fresh yeast and active dry yeast.  And the active dry yeast is a lot cheaper (buy in bulk from Costco/Sam's or other bulk store) and it keeps a LOT longer.  YMMV.

Mini Oven's picture
Mini Oven

looks questionable.  No wonder they want to test it.  Lol!

If you smell ammonia, and the outside is discolored with mushy soft spots; cut, trim or ditch.  Use only a nice looking cube of fresh yeast.  I have put yeast to proof and gotten a foam similar to milk foam.  With a clean looking yeast cube that smells light yeasty breaks under light pressure between fingers and has a starchy almost moist feel to it, no proofing is needed.   Crumble and use.   

Sugar doesn't feed the yeast as much as it serves to break apart yeast lumps chemically. Throwing in a big spoon of flour into the warm water or milk makes sense if you want to stimulate the yeast before adding to dough. 

 

Boron Elgar's picture
Boron Elgar

Actually, it is pretty easy to tell the viability of fresh yeast from feeling it. It should be crumbly and breakable, not overly soft and not creamy at all. You should be able to break it into chunks very cleanly and easily, with no smear.

There are two other things that feel the same when you break them apart- bear with me, as I am not sure if you are familiar with them - both India rubber art erasers and Silly Putty will "break" apart the same way fresh yeast will - cleanly and easily. No other characteristics are shared. :)

msova's picture
msova

Uhhh...u had up until you mentioned silly putty. I get the India eraser but unless you're talking about frozen or fifty year old silly putty. Anyhow....It's crumbly and smells fresh (typically buy it weekly) but I've definitely never seen a half inch of foam when proofing it, some tiny bubbling and a slim layer of go at best. Again, maybe this has to go with the yeast coming out of the fridge ?

Boron Elgar's picture
Boron Elgar

LOL. Actually Silly Putty can have a pretty clean break. I have some here on the desk.

Nevertheless, you needn't feel that a certain amount of foam is the only indicator for the fresh yeast. Once you lean the specific characteristics that truly "fresh" yeast has, it is all you need to guarantee its function.

It isn't like dried yeast at all, for which there is no way to tell by look or feel whether it is any good any more. Fresh yeast's condition is quite predictable by the look and feel. It is a win-win.

Boron

msova's picture
msova

Thanks all. is there any way, while on the subject of proofing yeast, to test Diastatic malt? I made some from wheat berries, but I also ordered some bobs red mill malted barley flour (definitely described on the website and over the phone as Diastatic but it doesn't mention it on the package ). just curious. 

msova's picture
msova

Ok. Definitely got a whole lot of foam just now using very warm almost hot water (about 100*) Using the fresh yeast (at least a week or so old). Didn't really measure things so I may have the proportions off. And after I had about 3/4" of foam I threw in some of my homemade d. malt and I have almost 3" of foam (in a 2 cup measuring container). Hmm....now I need to try it with the bobs brand. 

Kitchen Barbarian's picture
Kitchen Barbarian

I'm not sure what you would need to test diastatic malt for - it's basically flour with enzymes ...

msova's picture
msova

To test that the wnzes are kneed their and not dead (ie- killed off in production due to too much heat, or in transport in the back of a hot semi trailer). Anyhow...adding the malt to the foam greatly increased the foam at least double. so in sure both my homemade and the bobs red mill are indeed good. 

Mini Oven's picture
Mini Oven

with a control  1. (flour water yeast flour)

a second control 2. (flour water yeast sugar)

your wheat malt  3. (flour water yeast w-malt)

bob's malted barley  4. (flour water yeast b-malt)

I might use 50g flour, 50g water and 1g yeast then  add 5 g either more wheat flour, sugar, w-malt or b-malt.  mix well and pack into the bottom of 4 tall straight drink glasses or narrow jars, lightly cover.  Mark them, note the temperatures, time, aromas, etc. and let them race.  Mark and check on them every 30 minutes.  Malt helps fermentation.

I would let them peak and then watch them casually to see which ones separate liquids from solids first.  

If 1g of yeast is hard to measure, take all the water (200g) and dissolve some yeast into it and then divide into 50g portions. 

msova's picture
msova

Good idea. So, I've encountered this "measure water by grams" thing. I've got a digital scale so does that basically mean I just weigh the water? (accounting for the container of course). 

Mini Oven's picture
Mini Oven

50g water is 50ml of water    (at 4°C)   (or about 1.7 oz. for this experiment)

put the bowl on empty and turn on the scales.  then pour in water to measure

or  put the bowl on the active scale and hit the tare button to subtract the weight of the bowl.

Kitchen Barbarian's picture
Kitchen Barbarian

The weight of water for a particular volume depends on its temperature (it has to do with density). 

So neither rule of thumb - that 1 ml of water weighs 1 g, or that 1 cup of water (8 oz by volume) weighs 8 oz (avoirdupois) - is true except at extremes of temperature.

8 oz of water at "room temp" weighs about 8.3 oz, or roughly 235 g  (one cup btw is approx 236.6 ml)

At the freezing point (32F) the weight of one cup of water is 8.3436 oz or approx 236.5 g.  So unless your water is at the freezing point, 1 ml in volume does not weigh 1 g - it weighs LESS than one g

At 60F it is 8.3378 oz or approx 236.4 g

At 80F it is 8.3176 oz or approx 235.8 g

At 100F it is 8.2877 oz or approx 234.95 g, which I just round to 235 g

That's about as high as we care about as bakers.  So I use 235 g or 8.3 oz per cup

A cup of water doesn't weigh 8 oz until you get up to the boiling point.

And 1 ml of water does not weigh 1 g unless it's at the freezing point.

However, the error is much smaller if you assume 1 ml of water weighs 1 g - the only problem with that being that here in the US we don't measure volumes metrically, and recipes are given in cups and Tablespoons, not ml.

So to translate volume to weight for a recipe, use either 235 g per cup or 8.3 oz per cup.  Since I switched to translating a cup of water to 8.3 oz (or 235 g) a lot of recipes I was having trouble with before suddenly came together. 

I am not one of those people who can easily compensate for even such a seemingly small difference - I have to get really close to start with, and taking into account the approximate weight of water at room temp instead of using a value that is only true at extremes of temperature does that for me. 

I need one thing to be constant when translating a recipe, and it works better for me if the constant is the water - because the error in measuring water by volume is much less than the error in measuring flour by volume.  If I hold the water constant, I only have to worry about the flour, and all other measurements - yeast, salt, etc. - can be held constant relative to the water as well.  Since "one cup of flour" can weigh anywhere from about 3.5 oz to over 7 oz depending on who is doing the measuring, its not a good idea to try to hold the flour constant most times, LOL!

Antilope's picture
Antilope

I have a Tupperware measuring cup set. The "1 cup" holds 227 g of water. I also have a Pyrex glass measuring cup. At the 1 cup mark it holds 236 g of water. (I live in the U.S. and the cup sets were purchased here.) So I agree, it is better to weigh your liquids rather than measuring by volume, because different measuring cups may not agree.

Kitchen Barbarian's picture
Kitchen Barbarian

It's even worse than that - I "calibrated" my measuring cups and they were all off by at least 10%, and they were all different.  Measuring spoons too.  At least with the measuring spoons the amount is so small anyway that it doesn't matter THAT much ... So I weigh my liquids whenever possible.

msova's picture
msova

Jeeezo peeezo that's more than I ever thought there was to know about measuring water. Thanks!

Kitchen Barbarian's picture
Kitchen Barbarian

What can I say, weighing stuff really changed my baking - for the better!  And in particular, getting the right volume-to-weight equivalence for water made a big difference.  Most everybody I know thinks a cup of water weighs 8 oz, and I did too - until I looked it up after not being able to get several recipes to work for me, where flour was already given by weight but the water had been given by volume.