alpha amylase action doubts

Hi all guys again,

I would like this time to ask you a question that I couldn't find any answer for, but I bet that many, not well educated in chemistry homebrewers, would ask the same. The question is why alpha amylase is not able to make high fermentable wort. From readings about alpha and beta amylase one can only figure out that alpha is mightier cause it can break long chains almost everywhere.

Wikipedia says:

By acting at random locations along the starch chain, α-amylase breaks down long-chain carbohydrates, ultimately yielding maltotriose and maltose from amylose, or maltose, glucose and "limit dextrin" from amylopectin. Because it can act anywhere on the substrate, α-amylase tends to be faster-acting than β-amylase. In animals, it is a major digestive enzyme, and its optimum pH is 6.7–7.0.

Click to expand...

If the result of alpha amylase attacking amylose is maltotriose and maltose (+ the rest of the chain?) and maltose, glucose and limit dextrin (which is also long chain that I suppose can be broken again?) for me it looks like the activity of the alpha amylase yealds to the fermentables and alpha amylase breakable rest.
So, my question is what is actually unfermentable rest of alpha amylase long rest, since it can break every alpha 1->4 connections.

thank you for understanding,
and cheers

My understanding is that you want both alpha and beta present in your mash, if possible, they both work on the chains in different ways; so I don't see why alpha amylase wouldn't be part of a highly fermentable wort. Where did you hear that alpha amylase doesn't work well?

Hey,

the general information that you can get arround internet is that if u want more unfermentables and higher body beer, highet temperature rest with alpha amylase should be performed.

Im not a chemist and havent taken chemistry in 12 years, but I thought amylase created branched dextrins with a 1->6 bond which it cannot break down. I could be wrong.

It is said that dextrins are polymers consisted of glucose connected with 1->4 and 1->6 bonds. In my opinion (just logic not chemistru, unfortunately), after finite time all 1->4 bonds should be destroyed whether u use alpha or beta amylase. This is based on my reading on wikipedia and several other sources which may lack in some information.

I did some checking, found that (of course) How to Brew has a good a break down on how both beta and alpha amylase work.

http://www.howtobrew.com/section3/chapter14-5.html

As I said before, you need both to have a good break down of sugars for maximum fermentability. In a wort aimed at fermentability, you want a good mix of both, the alpha amylase breaking down the larger starches into pieces the beta amylase can then further break down into easily fermentable sugars; those two amylase compounds are most heavily present at the same time at the temperature of 150-154F. So, if you're aiming for a heavier, sweeter beer, you don't want to go below 150F, while if you're aiming for a dryer, lighter beer you need to keep things below 154F for the most part. There are other factors involved, but there you go.

I am a chemist, and I suggest you (all) check out the Chemistry of Beer course, beginning Aug. 18 by the Univ. of Ok. The program is called JANUX. It is archived, too, so it's accessible now; but you will need Google Chrome or Firefox.

Hi,

@AlCophile: Thank you for suggesting me the course. I will definitely try to follow it.

As for the section about starch conversion from Palmer's book, I read that many times. I must say I am a bit surprised that nobody asked here why alpha amylase is not able to make highly fermentable wort. From the information for amateurs, one can see that alpha amylase can break down everything that beta can and even more. My logic is that if there is finite numbers of 1->4 bonds, after finite period of time alpha should break them all. The problem is I couldn't find explanation of this.

Ah, see, this is where my background in computer programming comes into play. Let's imagine amylopectin as a long list of words with each word written on a slip of paper, in all these words, we're looking for the letter "m" (aka maltose). Let's now imagine we have two people who can search for the letter "m", but only in two unique ways; alpha can only look for the letter "m" by snipping apart at random until eventually he is left with "m" and beta who can only cut an "m" off if he finds it in the start or beginning of a word. Let's also assume we give alpha and beta only sixty minutes to find as many "m's" as they can. Now beta along will leave some "m's" behind, alpha on the other hand will leave a lot of random bits and pieces lying around, maybe some of them are an "m" but a lot of them aren't. However, clearly the best option is to let beta and alpha work together to get the "m's", alpha can cut at random and beta can look at each end for m's; that way beta isn't leaving "m's" behind and alpha doesn't need to snip at random as much. Yes given enough time alpha amylase would likely get the majority if not the entirety of the fermentable sugars from a grain, but since it works essentially at random and it has a time limit (aka your mash time) it doesn't have enough time to get everything chopped up. At least, that's my understanding of things (I'm not a biochemist, after all), perhaps a chemist could give you an even better explanation.

Since I have the same background, I like engineering approach. Your explanation is quite reasonable. I might have correct approach, but would be also nice if somebody from the world of chemistry can confirm. The next question would be, do we have more or less beta amylases than starch endings in the wort?

Hi all guys,

while reading an old book about technology of brewing in my mother tongue (serbian) i experienced illumination
So, I figured out if only beta amylase would be in the mash, the amylopectins (76-83% of all starches) would be only partially converted. The branches with reducing ends would be cut to the ankles and there would have been many amylopectin bodies in the mash. I am really happy that I realized this
Now, I read article about theory of mashing at braukaiser.com and would like to ask a question about following graphs concerning alpha and beta amylase activities:



What is the meaning of y axis?
Since the optimal temperature for beta amylase is 60-65 C, what actually means when activity for 63 C reach zero? Are there no non reducing ends in the mash any more? Are the life of these enzymes limited or are they "immortal" at their optimum temperature?

I have the same doubts for alpha amylase. We can see that its activity is falling very slowly at 63 C and much faster at 70 C. Why is that so? Is it because the concentratin of the substrate is falling rappidly at 70 C or because the lifetime is shorter?

I am not from the world of chemistry, but rather from electrical engineering. What I miss on those graphs is the amount of produced maltose in the case of beta amylase and some similar metric for alpha amylase.

Thanx and cheers

Nexy,

I am not quite sure about the labeling of the y-axis, but I am going to try and take as stab at your questions.

First, the y-axis appears to be the rate of enzyme activity with 1 being 100% or fully active.

The x-axis is time, so you can see the degradation of the enzyme activity with time and temperature.

The activity decreases faster at the higher temperatures due the the enzymes becoming denatured. The heat causes the protein structure of the enzyme to change shape, and it never returns to the original shape. This shape is important to the function of the enzyme.

The b-amyalse degrades much faster than the a-amylase for a given temperature.

The amount of produced maltose is highly dependent upon the concentration of the grain starches in the wort during the breakdown process. I would figure that the above data is derived from a fixed amount of starches for each of the temperature experiments. The rate of production of maltose is also highly dependent upon the concentration of the starches as well as the amount of enzymes present, which can vary depending upon the type of malt, the degree of modification during the malting process and the temperature and time of kilning of the malt during the drying process.

Very nice charts, by the way.

Thanx for your answer Oginme,
So, that means that activity drops due to enzymes being denatured. I thought that activity in the optimal temperature range drops due to the lack of reducing ends, which would mean that nothing can be done more.
One can also assume that if u mash at 65 C beta amylase will be deactivated after 30 minutes which means that longer mash at that temperature is worthless.
What I would really like to see is experiment with known number of of starch chains and their lengths, and the number of cleaved mailboxes as a function of time. But I suppose this kind of e experiment is impossible to perform.

Cheers