There are other players involved but fermentability is governed chiefly by the content of maltose and dextrine in the wort. The ratio between the two being important.Does the length of the mash affect fermentability, assuming the mash temperature is held constant through the entire mash? If so, why?
Assuming an adequate grain milling, longer mashes don't really affect the fermentability because the temperatures that activate the enzymes that produce the maltose and dextrine also destroy those same enzymes. That is the basis for choosing the mash temperature as the beta enzyme denatures quickly at the higher temperature so it cannot break down all the dextrines. Once denatured, it is done. It can't come back.Does the length of the mash affect fermentability, assuming the mash temperature is held constant through the entire mash? If so, why?
Thanks for the responses folks.Yes, mash time does effect fermentability. You will convert starches to sugar relatively quickly but after that you will continue to convert non-fermentable sugar to fermentable sugars as they are further broken down. Example: at a 150 degree mash at the 30 min mark you will have about 8%ish starches left, 42% unfermentable sugar, and about 50% fermentable sugar. After 60 minutes your starches will be close to 0%, UFS at 16%, and FS at about 84%.
Thanks for sharing that graph.http://www.woodlandbrew.com/2013/01/mash-temperature-theory.html
It is from the charts found on this page (hopefully the picture loads correctly)
And this does make sense to me since at most mash temps there are both alpha and beta amalyse active so if you are producing unfermentable sugar at higher temps that those unfermentable sugars can be broken down further into fermentable sugars.
Mash temperature is definitely a huge player in fermentabilty and I agree that the charts show this, I was not trying to say otherwise. I agree that I do believe that mash temp is the main player.Thanks for sharing that graph.
I don't interpret it the same way as you are. I don't agree with your interpretation.
Yes fermentability is increasing over the course of the mash but that is because the sugar content is increasing as the starch content is reducing. You can't use this to control fermentability except by not achieving full starch conversion.
At the earlier phase in the mash duration, unfermentable sugars are present in greater proportion yes. These longer sugars are not reducing in quantity but are only reducing as a percentage of the total sugar content as more and more starches are converted to maltose.
The other two graphs in the article however show the full picture where mash temperature is the key player, not mash time. The link you shared does not support your position.
I agree with you there but would argue the graph is in error, [EDT: THE GRAPH IS NOT IN ERROR, I AM ]not the science. Specifically the point of intersection of the red and green on the y axis and the starch curve leveling off too early. These are only models after all and not actual measurements taken on specific mashes. They should not be interpreted with the level of exactitude you are using IMO.With this interpretation, the 160 degree temp chart. At 30 minutes the total starch is about 3%ish meaning that the total sugar content (FS + UFS) is about 97%. Over the next 30 minutes it shows the starches decreasing to roughly 0%, a difference of about 3%, but it shows the UFS and FS changing significantly more that 3%. So that says that the UFS is being broken down into FS.
Fair point. I need to start brewing enough to be able to actually do this type of experiment.I agree with you there but would argue the graph is in error, not the science. Specifically the point of intersection of the red and green on the y axis and the starch curve leveling off too early. These are only models after all and not actual measurements taken on specific mashes. They should not be interpreted with the level of exactitude you are using IMO.
The other interpretation is that the dextrin is being converted to maltose by the action of alpha amylase. Not something I am familiar with but concede I have much to learn on this specific topic.
Been thinking more about this and I've come to the conclusion that I'm completely wrong. I thing your interpretation is completely right. The non-fermentable sugars being repeatedly cleaved into simpler fermentable sugars by alpha and/or beta amylase still present and not as yet denatured.Fair point. I need to start brewing enough to be able to actually do this type of experiment.