Test #5 - Fermentation under different conditions, medium wet dough

Setup from left: fresh yeast (control trials) / old yeast / plenty salt (2.5% = 12 g) / milk instead of water



Here I make a test where I use 1/8 pkg of yeast for all batches of a medium wet dough (70% hydration) (like in test # 3). And then I do as follows:

Fresh yeast is the control experiment. Which corresponds to the 1/8 package of yeast in the dough, in an test #3.

is the control experiment. Which corresponds to the 1/8 package of yeast in the dough, in an test #3. Old yeast is yeast that is right at its "best before" date. It appears dry and brownish, but otherwise there should be nothing wrong with it.

is yeast that is right at its "best before" date. It appears dry and brownish, but otherwise there should be nothing wrong with it. Many recipes uses milk instead of water , so it's nice to know what happens to the fermentation time with milk.

, so it's nice to know what happens to the fermentation time with milk. Plenty Salt: you typically use between 1.5% and 2.5% salt in a bread. The 2.5% is among the highest that is realistic to use. And since salt inhibits the fermentation is also handy to know by how much.

Conclusion of the experiment

This result is a bit funny compared to the other results I've had, I would have expected a fermentation time at 2 - 2½ hours for the control experiment, and 2 hours, from my rule of thumb in relation to the amount of yeast. But it actually went a little faster.

I think that was because this video was recorded on a warm spring day with the sun shining through the window. So the room I recorded in has had to be 24°C-26°C (75°F-79°F) degrees. You can also see that the video "flickers" a little due to the sun that shines into the room once in a while. but it does show very well that it is a biological process with living organisms that is depends on many things. Especially with the smaller amounts of yeast, a temperature difference shows its influence.

The previous tests/videos were made on cool spring days, so my kitchen was cooler too. The fermenting batches was placed close to the outer walls, that would also have been cooler on the cold days.

Another funny thing is that the dough with the old yeast actually raises faster than dough with it the fresh yeast. This is a surprise. I suspect either it may be because I used a different bag of flour. Although it's the same brand of flour perhaps there may be the difference. Or I could have cut the yeast a little crooked so it was not exactly 1/8 of a package. However, that is not as likely as I was pretty careful. The difference is approximately a hour compared to 7 quarters hours for the total fermentation time, which is a 14% difference. So it does not mean sooo much in practice over a 2-hour fermentation. But if it IS because I've switched to another bag of flour, is nevertheless an interesting result which I had not considered.

The dough with the maximum amount of salt took half an hour longer to ferment. Or 1/3 extra fermenting time. I believe that is very realistic as a general result.

According to my experience a dough without any salt at all raises like crazy. But since the only place where an unsalted bread is typical is in Tuscany (due to tax-political problems in the renaissance), I therefore think that "no salt" it is an unimportant thing to measure in the rest of the world :-S So I only measured the typical ranges of salt in bread. "a little" and "a lot" ...

The dough with milk is yet another slow surprise which may be due to several things. The milk came straight from the refrigerator and is 5°C (41°F). I did it this way because I believe this was the most realistic situation when you ferment something with that little yeast as in this test. You don't heat up the milk first. However, the cold milk may have been a reason for the extra fermentation time. The tap water I used for the other tests was approx. 16-18 ° C for comparison.

Milk contains a lot of "solids" even though it seems like a liquid. They are the ones that can turn into cheese, sour milk, Greek yogurt, etc. When I made my bread recipes I tried to mixing some batches by touch to compare how wet the dough felt during kneading. I found out that I actually needed to make a dough with 4 dl (1.7 cup) milk for a dough comparable to one with 3 dl (1.3 cup) water, and the I had to use 1 dl (0.4 cup) less of flour, to offset the solids in the milk.

So a dough based on milk, with the same liquid percentage as a water based dough, is much drier. Whether it played a role I do not know. There is nothing in the tests where a dry dough seem to go any slower.

Milk contains fat which inhibits fermentation. I used semi-skimmed milk with 1.5% fat so it should not have much impact. On the other hand, there are sugars and proteins in the milk which should facilitate the ferment. So I am somewhat perplexed. I have no idea why milk is slower. It's against my intuition. But it takes about 1/3 as long to ferment so it's pretty unique. If I should ever want to do more fermentation tests in the future it would be a fine candidate for further tests.

