Protein rest and starch conversion

[nexy_sm]

Hi all guys,

I would like to ask a few questions about protein rest and starch conversion. The reason I am writing is improving the taste of my beer, especially the it's body.

It is written in some pages that in order to improve body of the beer, protein content of the wort should be improved, usually by addng unmalted barley oats or wheat. What I don't understand is how long should the protein rest be. As an example, i brewed two different belgian wit beers. The first recipe was contained about 20 % of malted wheat. I mashed in at arround 50 C and rised to 62 for starch conversion. The final beer had really good head, the retention was good and the beer was hase.
The second beer contained 30 % of unmalted wheat and 20 % of malted wheat. I mashed in at 57 for protein rest and stayed there for 15 minutes. The final beer doesnt have head at all, and it is not that hasy.
So my question how much should I reduce protein resty in the second recipe in order to improve body and the head?

The second doubt is about starch conversion. Namely, as far as I understood, beta amylaze can only chop sugar molecules from the end of the long starch chains, while alpha amylaze cut the chains at random places. They say that if only beta amylaze is to be used we will get most fermentable wort, but it will take some time to finish. However, for having full bodied beer, it is suggested to use alpha amylaze for main conversion in order to have more unfermentable sugars in the wort. The classical mash schedule is also stated as 15 minutes at 62 C and the rest at 70 or 72 C. I would like to know, to what extent are long starch chains chopped by beta amylaze depending on the time. Does this happens linearly or not. The second doubt is what would happen if we use only alpha amylaze, how fermentable wort will we get?

best regards and I hope someone wil lhave time to read this wuite long post.

 

[mabrungard]

Only a few beer styles benefit from protein rests since most malts are well converted already. In fact, those minor additions of unmalted grains are to leave your wort with a minor beta glucan and protein content that will enhance the body you want in the beer. You are better off with mashing at a single mid 60C range and adjusting the unmalted grain content to produce the body you want.

I do caution against mashing with a single rest at temperatures above 68C since the resulting wort tends to be too unfermentable and the resulting beers too chewy and sweet. I find that creating a more fermentable wort and adjusting the bittering to maintain the balance is more successful. Then the addition of a small percentage of those unmalted grains is the way to add the degree of body you want in the beer. Of course, there ARE cases (such as brewing session beers) where you will want a single mash at greater than 68C. But they are the exception.

 

[nexy_sm]

let say that I want to make the same wit beer that I mentioned in my post. The one that contains 30 % of unmalted wheat (flakes). My idea is to mash in at 58 centigrades and to start immediately temp rise in order to reach 62 centigrades in 15 minutes or so. I expect in that way to break a part of the proteins and part of them to preserve. But I am not comfortable about the time, don;t have sense of it in that purposes. What should I roughly expect with that approach?

thanx and cheers

 

[ajdelange]

The key to good head is to have a protein spectrum with a heavy concentration in a certain band of molecular weights and I don't remember what that is (nor have access to my library at the moment). Low MW protein fragments just get consumed by the yeast. High MW fragments coagulate and drop out during the boil and those in the middle stick around to give that great head we all want. The advice that goes with this is to manage the protein rest according to the protein modification level of the malts (0 if unmalted) so as to get those mid-range MW fragments. Unfortunately I don't have any specific advice to give here. I used to make wits but it's been so long that I can't remember what the mash program was. I'd research the style including the old traditional way which was quite complex as I recall. In the end it is only experiment which will answer your questions.

 

[nexy_sm]

Hi all guys and thank you for your answers,

If somebody is able to give me some explanatino regarding following questions I think I will be illuminated in a way.
In the book about Belgian Ales, Mr. Pierre Rajotte says that he brew with following mash schedule:
1. mash in at 58 degrees
2. rising temp to 62 in 15 minutes
3. rest at 62 for 15 mintes
4. rise temp to 66 fot 15 minutes
5. rest at 66 until iodine test show that starch conversion is over
6. rise temperature to 72 in 15 minutes
7. rest at 72 for 15 minutes
6. rise temp for mashout

Since he brewes belgian style ales which are not heavy bodied I assume that in the firs conversion rest at 62 beta amylaze cuts some endings of the starch chains. At 66 maybe both alpha and beta amylaze are active and the starch is completely converted leaving behind besides fermentable sugars some dextrins and other unfermentable sugars which I don't know, but not starch. At 72 these unfermentables are more broken into fermentables and unfermentables, but since alpha amylaze is not able to reach joints of the chains it will leave some unfermentables behind.

What I would like to see is some kind of graph of beta amylaze activitiy in a wort, for example x axis as time and y axis percentage of produced fermentables. Would this function be almost linear? By knowing this I can understand better which ratio of fermentables/unfermentables is optimal for beer body for example.

If we take a look at his pages:
http://www.castlemalting.com/CastleMaltingBeerRecipes.asp?Command=RecipeView&RecipeID=7 and http://www.castlemalting.com/CastleMaltingBeerRecipes.asp?Command=RecipeView&RecipeID=21
the first recipe is described as sweet. Both recipes has the same alcohol content even if the first has lower original gravity. Is this related to mash schedule? Is it possible that in the first recipe, the long beta amylaze rest provided the main part of fermentables? Is for example (hipothetically) possible to achieve the same results if u do x minutes beta rest and 0 minutes alpha rest and y minutes at beta and z minutes at alpha where (maybe) x > y + z?

a bit longer post but I had inspiration,
Best and cheers