Fundamental questions regarding enzymes

OK. I have a working understanding of yeast, how they propogate and how they turn wort into beer.

I also have an understanding of the actions of alpha and beta amalayse enzymes in breaking long chain sugars found in the starches of malted grains into shorter chain sugars that yeast can process into Alcohol and co2.

I would like to get a fundamental understanding on the SOURCE of the enzymes.

1. Do they reproduce themselves like yeast?

2. Are they "consumed" by the process of breaking long chain sugars into shorter ones like an acid neutralizing a base, or would one enzyme (molecule?) *theoretically* work endlessly to break all the sugars in a mash?

3. How can I check a recipie to verify there is sufficient enzymes present to convert the grain bill during a typical mash session?

4. How do I determine which grains contain enzymes and which do not? Are there grains other than 2 row and 5 row malted barley that contain sufficient active enzymes to mash a 10 lb grain bill?

4. Are the enzymes present in the grains on the stalk or are they formed somehow during the malting process?

5. What is the usual (grain life cycle) function of the enzymes present in grains? Do they convert starches to sugars that the seed uses to break out of the husk and root, or some other function entirely?

6. What is the specific mechanism by which enzymes are denatured (conversion halted) by heating? Are they killed like yeast, or some how turned off? If turned off, can they be turned back on?

Sorry, this wasn't planned to be a multi part question, it just kept growing. The WIKI and the forum history have lots of info on how enzymes work, but not where they come from. Any suggested readings would be greatly appreciated.

I'm not smart enough to answer your question, just want to follow along and learn something too.

william_shakes_beer said:

1. Do they reproduce themselves like yeast?

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No. Enzymes are proteins found in the barley. They are there so that the germinating seed can produce the energy it needs. In a given mash you have the enzymes you have. No additional enzymes will be produced.

william_shakes_beer said:

2. Are they "consumed" by the process of breaking long chain sugars into shorter ones like an acid neutralizing a base, or would one enzyme (molecule?) *theoretically* work endlessly to break all the sugars in a mash?

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No, they are not consumed but they can be denatured (rendered ineffective) by excessive heat and improper pH. They work the way they do because of their shapes which allows them to bind starch in such a way that the certain bits are held in position such that the probability of hydrolysis of the bonds in the starch (or protein molecule) against which the particular enzyme is effecting is increased many times. Unless they are denatured somehow they can catalyze the lysis of indefinite amounts of starch (or protein - different ezymes).

william_shakes_beer said:

3. How can I check a recipie to verify there is sufficient enzymes present to convert the grain bill during a typical mash session?

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By looking at the specification sheets for the malts you are using and calculating the diastatic potential. Some guys worry about this a lot. I never have.

william_shakes_beer said:

4. How do I determine which grains contain enzymes and which do not? Are there grains other than 2 row and 5 row malted barley that contain sufficient active enzymes to mash a 10 lb grain bill?

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Again, by looking at the malt spec sheets. The base malts tend to have the highest diastatic potentials because they receive the least kilning (remember that excessive heat denatures enzymes)

william_shakes_beer said:

4. Are the enzymes present in the grains on the stalk or are they formed somehow during the malting process?

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They are in (or just under - can't remember which) the aleurone layer in the barley corns. They are, as mentioned above, present in the unmalted grain. The object of malting is to let them partially convert the starch (gemination) and then arrest the process (kilning) without denaturing them.

william_shakes_beer said:

5. What is the usual (grain life cycle) function of the enzymes present in grains? Do they convert starches to sugars that the seed uses to break out of the husk and root, or some other function entirely?

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Yes but they have a lot of other functions too. Most of the complex biochemical reactions of life are mediated by enzymes.

william_shakes_beer said:

6. What is the specific mechanism by which enzymes are denatured (conversion halted) by heating? Are they killed like yeast, or some how turned off? If turned off, can they be turned back on?

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As mentioned above the ability of an enzyme to serve as a catalyst depends on its shape. The shape depends on charge (which is controlled by pH) and by cross linking bonds. If these are broken by heat (increased kinetic energy) they cannot reform. The classic example of denaturing of a protein is the cooking of egg white. The classic example of the effect of pH is adding vinegar to the water when eggs are poached.

william_shakes_beer said:

Sorry, this wasn't planned to be a multi part question, it just kept growing. The WIKI and the forum history have lots of info on how enzymes work, but not where they come from. Any suggested readings would be greatly appreciated.

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Any textbook on brewing will have a detailed description of the anatomy of a barley corn, and the effects of malting on it.

william_shakes_beer said:

Sorry, this wasn't planned to be a multi part question, it just kept growing. The WIKI and the forum history have lots of info on how enzymes work, but not where they come from. Any suggested readings would be greatly appreciated.

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It looks like all your questions were answered above, but as far as "where they come from," any Biology textbook will explain this for you. Enzymes are proteins that are formed by amino acids through a process called translation and are used for a variety of reactions during plant metabolism. Amino acids are formed within a cell, and so on down the line. It would take a very long time to explain all of these processes, especially since I've been out of college for so long.

AJ nailed it.

I do have a caution regarding the question of 'if there is sufficient enzymes'. If you are mashing with a high percentage of typical base malt, then you don't really have to worry as AJ indicated. But, if you are using one of those quasi-base malts like a brown malt or dark munich that might have only enough enzymes to self convert, then you need to worry if there are going to be any other grains needing enzymatic conversion.

You do a mass-based averaging of the total Lintner values of all your grain in the grist. I recall that you want a averaged value of at least 35 Lintner for the grist.

mabrungard said:

...if you are using one of those quasi-base malts like a brown malt or dark munich that might have only enough enzymes to self convert...

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As I don't worry about this I really don't know that much about it but this very phrase (and one sees it frequently) contradicts my understanding of how enzymes work as it implies that a certain amount of enzyme is required to convert a certain amount of substrate or that the enzyme "wears out" after a certain number of conversions. My thinking is that if there is relatively little enzyme then the rate will be in the saturated region of the rate curve so that the rate will be limited by the turnover rate of the enzyme and its amount i.e. slow. But complete conversion should take place - eventually. ???

Hi all,

It has always been my understanding that enzymes do degrade over time and that the rate of enzyme degradation is influenced by mash temperature, pH and other aspects of mash chemistry. The end result is that if the mash is sufficiently lacking in amylases, conversion will not only be slow, but the mash may not convert completely before the enzymes are effectively gone. I also vaguely remember that this occurs in a few hours at typical mash conditions.

I was mentored in my early home brewing career by a pro with a fermentation science degree and pilot brewed some light beers for him using bottled amylases. I am fairly sure this understanding developed out of the conversations surrounding those brews.

Additionally, although I cannot fully explain the basic science, all chemical reactions take time. The rates of reactions can usually be described in terms of half-life. The denaturing of amylases in a mash is no exception. Enzyme activity of malt will degrade over (a very long) time sitting in the sack on a shelf. It will certainly degrade faster in the presence of moisture and heat.

Adam

adamreef said:

It has always been my understanding that enzymes do degrade over time and that the rate of enzyme degradation is influenced by mash temperature, pH and other aspects of mash chemistry. The end result is that if the mash is sufficiently lacking in amylases, conversion will not only be slow, but the mash may not convert completely before the enzymes are effectively gone.

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That makes sense.

adamreef said:

Additionally, although I cannot fully explain the basic science, all chemical reactions take time.

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It's pretty simple. A starch molecule gets hydrolyzed when a 1-4 bond gets pasted by a water molecule coming at it with just the right speed from just the right angle. The rate of the reaction depends on the probability that the water arrives with the proper orientation and speed and that the substrate is oriented properly. An enzyme attracts the substrate and holds it with the 1-4 bond exposed at such an orientation that the probability of successful attack is increased. The reaction takes place faster.

adamreef said:

The rates of reactions can usually be described in terms of half-life.

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The rate of the reaction is described by rate constants (there are 3 in the simplest model) but the decay in the concentration of working enzyme can be modeled by a half life and it is entirely reasonable that the functioning half life of an enzyme at 149 °F is hours whereas at room temperature it is months. That's the bit I was missing. Thanks.

Thanks for the lessons. A much simpler question: as a *general* rule, if I have an AG recipie, say 12 lbs, and at least half the bill is a base grain, such as 2 row or 6 row, I have enough enzymes to process the entire mash. True?

william_shakes_beer said:

Thanks for the lessons. A much simpler question: as a *general* rule, if I have an AG recipie, say 12 lbs, and at least half the bill is a base grain, such as 2 row or 6 row, I have enough enzymes to process the entire mash. True?

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As a general rule, yes. As long as you stick with pale two row or six row. There are some weakly diastatic malts like Munich that might be a problem with a high percentage of adjuncts, but you would be very unlikely to use them that way anyway.

Adam