'Enzymes' in food... confused...

[gus_tatory]

it seems we routinely hear such things in regular 'foodie' conversation, such as:

--if the food supply starts to become more irradiated (for shelf life purposes) our food will have fewer enzymes;

--'raw' food is better because it has more active enzymes;

--if you brew green tea with too hot water, or microwave veggies, you will lose their beneficial enzymes;

--the further market veggies are harvested from your house, the fewer enzymes they will have. ('living' food.)

i have re-read my McGee (On Food & Cooking) and my Larousse Gastronomique under several headings (bread, beer, carbohydrates) in search of these elusive enzymes. several are fairly obvious, like papain (the papaya enzyme used to tenderize meat) and lutein.

but what are these enzymes (literal translation: 'in yeast'), and what is it that kills them (over-processing)? i ask in the spirit of curiousity and learning, but also because i am getting tired of certain proponents telling me my food may be 'dead', or enzyme-free by the time i get it.

my apologies for starting a food-science nerd discussion, but i find this interesting. what is this enzyme business?

anyone with food-chemistry background--or not--is warmly welcomed to this thread...

[SuzySushi]

I don't have a food chemistry degree, but IMHO, the "raw food" movement, with its talk of "living enzymes" is a bunch of bunk... or pseudoscience, if you will. While certain vitamins & other nutrients leach out of foods that are boiled (and go into the cooking liquid, which is why the famed Southern "pot likker" is so nutritious), whatever enzymes are in "live" raw food are killed as they make their way through the acids of the human digestive system.

[jackal10]

I don't have a chemistry degree either, but I'm listmaster of the Molecular Gastronomy mailing list. I agree what you have been told is pseudo-science. Its mythical, like astrology, based on belief rather than fact. In some cases (such as the statement that irradiation affects enzymes)

Enzymes are active biological chemicals that perform various processes in living cells. As they are complex chemicals, they are fairly easily broken down, for example by heating to much above 55C/140F, or being in the wrong too acid or too alkaline or too salt environment or in many other ways, and in some cases just with time.

However, there is no evidence at all that eating enzymes does anything for us, and in any case they are broken down by saliva and the stomach acids. This is just as well, since you would not want, for example, digestive enzymes such as papain busy digesting your gut.

When I was young I was told the same myths but with Vitamins instead of enzymes. Like enzymes vitamins are complex biological chemicals that can be distrupted with too much heat, or leached out, and to some extent its true that poorly prepared or stale food has slightly less nutrients than well prepared food. However the difference in a normal diet is trivial, and if you are so worried about it, then take a daily multivitamin pill.

If you are really concerned about nutrition, then more worrying was the recent report that the majority of Calories in a US diet are from soda. Ban soda.

[jsolomon]

Wow, only two posts before someone with a chemistry degree posts. Either there is a large number of chemists on eG, or the title scared everyone away...

Classically, an enzyme is a catalyst. Which is to say, an enzyme generally works on a discrete chemical reaction between (often) 2 chemicals with a defined energy to perform that chemical reaction. The magic of the enzyme is that it lowers that energy, and generally by lowering the energy, also speeds up the reaction.

Enzymes are usually proteins folded in a certain way. Sometimes they have sugars, metal ions, or lipids associated with them for reasons of chemistry, or to hold them in their shape.

But, the thing that holds most proteins in their folded position is the hydrogen bond, the same thing that causes jello to gel. So, when you apply the heat, you break those bonds, and most often the proteins, enzymes in this case, come unfolded, and then it's extremely unlikely that they'll cool and refold into their enzymatically active form.

However, most enzymes are designed to have a lifespan within the cell or body so that they can be under cellular control, which is to say that they are made digestible. So, most enzymes get deactivated and digested readily within the stomac and small intestine anyway.

What kills enzymes chemically is anything that causes them to fold or refold improperly. Addition of acid can do it, think of curdled milk. Adding too much salt can do it. Heat can do it. Cold can do it. Time can do it. Other enzymes (like papain) can do it. Even removing a salt, or water, can do it. Also, adding large percentages of alcohol can do it.

When you get into cellular chemistry (note, I'm staying away from the B**chem word because I'm generally a p******* chemist) it becomes awe-inspiring to realize how close to on the head of a pin we dance with ion concentrations, sugar concentrations, cellular timing, etc... and we're completely unaware of doing it ourselves.

[Pan]

Is it untrue that papaya and pineapple help digestion because they contain enzymes that help settle the stomach before they are themselves digested?

[nr706]

Re: the raw food myth, I believe I read somewhere that cooking actually increases the bioavailability of some beneficial nutrients, like the lycopene in tomatoes and the beta-carotene in carrots. And I think I also read that cooking disables some potentially harmful compounds, like the oxalic acid in spinach. Can anyone confirm, deny or elaborate?

[gus_tatory]

...Which is to say, an enzyme generally works on a discrete chemical reaction between (often) 2 chemicals with a defined energy to perform that chemical reaction.  The magic of the enzyme is that it lowers that energy, and generally by lowering the energy, also speeds up the reaction...

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wow--thanks folks. this information only motivates me to learn more. fascinating...

[jsolomon]

Re: the raw food myth, I believe I read somewhere that cooking actually increases the bioavailability of some beneficial nutrients, like the lycopene in tomatoes and the beta-carotene in carrots. And I think I also read that  cooking disables some potentially harmful compounds, like the oxalic acid in spinach. Can anyone confirm, deny or elaborate?

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It does, in some cases. But, you can also go too far. For instance, eating charcoal and metal oxides (cooking your food to beyond burnt) is not good for you.

But, most plant matter is made up of cells which are encased in an insoluble, inert, cell wall of very complex carbohydrates that humans cannot digest. So, we end up with two major choices: get rid of the cell wall by mechanical means (chew, chew, chew, chew, chew, chew... ad nauseum) or by chemical means: cook, ferment, pickle, nixtamalize, etc.

In truth, cooking also destroys some of those as it liberates them, but so many are unavailable unless cooked, that it is better to cook some things (like beets) than to eat them raw.

Unfortunately, your mileage will vary widely. Some nutrients survive cooking much better than others. Vitamin C, you can kiss goodbye if you put the spurs to it, for instance. It's just too chemically reactive. But, vitamin C isn't an enzyme.

[jackal10]

Yes. We can deduce from the structure of our teeth and digestive systems (e.g. can't digest cellulose like leaves and grass) that way back when mankind was basically a carrion scavenger (not big enough to make our own kills, but eyes face forward, so a hunter rather than preyed on), with occaisional feasts of fruit and nuts. That is one theory why carbohydrates make us lay down fat, to store for hard times between gluts. I note the "raw food" movement doen't generally advocate eating raw carrion meat, rotten enough to be tenderised.

The discovery of fire and cooking allows us to utilise a much wider range of food stuffs, and so was a major contributory factor to our evolutionary success.

[jsolomon]

wow--thanks folks. this information only motivates me to learn more. fascinating...

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The wikipedia has a reasonable entry on enzymes.

[Smithy]

You should never apologize on this forum for starting a food nerd discussion!

I asked Harold McGee about his opinion of the Raw Food movement and their claims during a Q&A session last year. You can read my question, and his response, here (click). That same Q&A session has a lot of other good food nerd discussions.

[Chris Amirault]

Thanks, everyone, for your fascinating input! I must say I kept thinking about those old Russian peasants eating Dannon yogurt and living until they were 104....

[slkinsey]

It should be pointed out that there is a big difference between eating a food that contains enzyme-producing bacteria and just eating a food that contains the target enzyme. The enzyme-producing bacteria may (depending on the bacteria) survive the environment of the stomach, take up residence in the intestines and continue to produce the target enzyme or provide other benefits (such as breaking down molecules we cannot digest into molecules we can digest).

That said, presumably some non-produced enzymes do appear to have some activity in the digestive system. Two good examples are lactase pills and Beano. Whether there are enzymes that provide any substantial benefits when consumed in the form of natural raw foods strikes me as unclear at best.

[FoodMan]

Click here for Wolke's take on enzymes in raw foods. It is in line with most comments here...just a little funnier

Elie

[gus_tatory]

Click here for Wolke's take on enzymes in raw foods. It is in line with most comments here...just a little funnier

Elie

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Excellent article; thanks Elie!

This short quote sums up why i asked the question in the first place:

"Enzyme" is one of those words that people toss around without knowing what it means. Put down this newspaper for a moment and ask the person nearest you what an enzyme is. (I'll wait.) Odds are that you'll hear something vague, like "one of those tiny little things that keep us healthy."

[jsolomon]

Is it untrue that papaya and pineapple help digestion because they contain enzymes that help settle the stomach before they are themselves digested?

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I hate to be pedantic, Pan, but I think you're confusing lines between enzymes and (using a very broad definition) drugs--which I shall henceforth call "signal molecules".

I do not believe that the enzymes in papaya and pineapple are human signal molecules, but I do believe that some of their enzymes may produce stomach-settling signal molecules.

However, as far as settling a stomach goes, it may simply be psychosomatic, or even more simply (and likely, IMO), the sheer presence of bulk in the stomach.

[ellencho]

I can't believe I missed this thread, I've got a degree in biochemistr and one in biology and I currently work in biochemistry.

To answer Pan's question and to follow up on jsolomon's response, I believe bromelain and papain (enzymes from pineapple and papaya respectively) sort of pre-digest your food for you if you keep your meat in some sort of marinade containing either of those two fruits. Bromelains and papains are proteases, meaning that they can break down proteins, which is why if you marinate meat in either of those two fruits for long enough, it'll turn your meat into mush.

I don't believe however, that papains or bromelains actually settle one's stomach, their job is just to break down proteins, but perhaps using them to get a head start on digesting proteins might be good for someone who might have trouble digesting proteins.

It's similar to how ptyalin (a type of amylase), which is present in saliva digests starches into simpler sugars before they get to your stomach for further digestion. Amylase also is present in fruit, which breaks down starches and turns them into simpler sugars which makes riper fruits taste sweeter.

And to add onto jsolomon's point, in terms of settling one's stomach, I suppose the indigestion one might feel from eating a lot of meat might come from your stomach producing extra stomach acid to compensate for the rise in pH that occurs when there's too much food in your stomach. I don't think that the consumption of papain or bromelains will settle one's stomach if you've got indigestion. In order to settle one's stomach you'd have to re-establish some sort of stomach acid equilibrium.

[jsolomon]

I'm not convinced it is a pH thing.

So, I did some quick web-work. And... I'm still not convinced. However, there is at least some evidence that it is due to either small peptide chains if not amino acids (which are known neurotransmitters and signalling molecules) are at the root of Pan's question.

And, even things like free SH groups (from reduced cysteine residues) and alkylated SH groups (from unknown stomach crunk).

PubMed abstract of gastric protection

So, to expound slightly, I think that people who find that papain soothes their stomach are predisposed to a sensitive gastric mucosa (the skin inside your gut) and the products of a papain digestion of proteins signals their stomach to produce more protective compounds which then reduces the acuity of the current irritation.

Or, as I would tell my 4 year-old niece: it makes your belly produce snot so your food is slicker and don't stick nowhere.

[ludja]

I also searched on PubMed a bit, with key words like:

exogenous enzymes digestion

(exogenous means derived from outside the organism, i.e. exogenous enzymes or proteins that are in food that is eaten as opposed to those enzyme that are produced within our body)

Did not come up with many relevant hits, as judged by perusing the titles and abstracts. Per what jsolomon just mentioned above, there are some papers that mention "bioactive peptides", i.e. chewed up bits of exogenous protein or enzyme that may have some activity in the stomach.

There were also a bunch of papers dealing with the effects of adding exogenous enzyme to poultry feed and watching the effects.

I got no hits under 'papain exogenous digestion'

[ellencho]

I think I completely misread Pan's original post. He asked about aiding in digestion, but I took it as in aiding in digestion in people who had indigestion, something like heartburn/acid reflux. And I wasn't sure if taking bromelain/papain supplements would necessarily work like an acid reflux medication. But I see where jsolomon and ludja are going with their posts now. My bad. Carry on

[Chris Amirault]

No apologies needed, ellencho. This has all been very interesting!

acid refluxily yours,

Chris

[turkeybone]

Bromelains and papains are proteases, meaning that they can break down proteins, which is why if you marinate meat in either of those two fruits for long enough, it'll turn your meat into mush.

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This is why you have to use canned pineapple if you want to use it in conjunction with jello...

[gus_tatory]

No apologies needed, ellencho. This has all been very interesting!

acid refluxily yours,

Chris

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"acid refluxily yours"

best. signoff. ever.