February 12, 2016 - 10:35pm
hypothesis and questions about preferments
dear all,
Being new to using preferments in bread, I have studied its use and preparation methods online. Based on what I've learned, I can't help to have the following hypothesis about preferments.
- Since the direct consequence or (maybe objective too) of using preferments is to have a readily available large yeast population at the first working stage (mixing I guess), this relatively large yeast population should exhaust the nutrition in the dough faster than a dough prepared without preferments.
- Since the nutrition in the dough prepared using preferments can be exhausted faster, it has a relatively high risk of yeast running out of food, and a higher risk of poor performance in the second proofing and baking.
- This risk may be mitigated by adding sugar into the dough.
Is my hypothesis reasonable?
and my question is: most of the information sources about preferments say that it enhances flavor (and if I remember correctly, reducing bulk fermentation time too), is this the main if not only purpose of using preferements? Could it lead to better crumbs or volume? and what differences can be made in the flavour, sourness?
Thank you !
Liming
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You need to consider several points for starters
- What will ferment faster - straight or prefermented dough depends on how much yeast you put in either.
- Effect of preferment on the fermentation will depend on the percentage of prefermented flour.
- Nutrition in the dough never gets exhausted completely. During the fermentation we use something on the order of 1% of potentially available sugars. To temporarily exhaust available nutrients, to have the yeast outrun amylolytic enzymes, you need to overload dough with yeast. That's not something to really strive for.
I use pre-ferments for a couple of reasons:
I don't worry too much about the science; I like to try things and see what works!
that yeast need to feed on. To do thhis they use 100% malted grains which tale 5 days to sprout and dry the grains. Then they mix the malted grains with water and take the temperature up to 140 F for 1 hour and then to 150 F for an hour and then up to 170 F to denature the enzymes that break down the grain starches into sugar. At this point most all the starch is broken down to sugars. Then the yeast is added and the mix is allowed to ferment for a week at room temperatures. This converts most of the sugars into alcohol and CO2. Now the yeast have little to eat.
To exhaust the food in bread dough you would have to make beer instead of bread. Since bread is made at room temperatures, at much lower hydration levels, using almost 100% un-malted grain, over a short period of time, the idea that you could exhaust the sugars needed by LAB and yeast in the dough is - slim to none.
Happy baking