The pellicle: are we sure?

[Dave the Cook]

On page 78 of Polcyn and Ruhlman's Chacuterie, in a short section entitled "The All-Important Pellicle," the authors say:

If you put damp meat or sausage into a smoker, it won't pick up the smoke as effectively as it would if dried uncovered in the refrigerator overnight. Yes, food will pick up smoke if you don't give it a chance to develop a pellicle, but the end results will be superior if you do.

In the more clinical Professional Charcuterie, John Kinsella and David T. Harvey aver (pp 57-58):

Smoking is usually preceded by or combined with a period of air drying . . . in an environment of controlled temperature and humidity

. . . .

Drying prepares certain items for the smoking process; a think skin, or pellicle, forms which helps the product acquire the proper smoke finish

Unless I've been in a terrible hurry, I've adhered devoutly to this advice, never mind the ambiguity that the two passages introduce: what's the difference between "pick up smoke . . . effectively" and "proper smoke finish"? It didn't matter: both sounded like good things.

However. The other day, I was leafing through the second edition of McGee's On Food and Cooking. (Yes, I am underemployed.) On page 176, I came across this:

. . . smoke vapors are deposited most efficiently onto moist surfaces, so "wet" smoking has a stronger effect in a shorter time.

So now I'm confused. Besides tradition, what's the basis for encouraging the pellicle? Is there proof that it indeed has the intended effect(s)? Has anyone done side-by-side comparisons?

[Chris Amirault]

I'm like Dave. I have followed the pellicle brief diligently. I pick up McGee for fun. I'm confused too.

What is this pellicle, anyway? How deep is it exactly? Perhaps part of what happens is that the dry surface becomes moisturized by the ambient water -- which is impregnated with the water-soluble compounds in smoke. So as the flesh rehydrates, the compounds are transmitted into the meat. Since all air has some humidity, maybe we never thought of it as sufficiently humid and were only focusing on the pellicle....

I mean, what about misting shoulders and butts while in the smoker? Does this contribute to or prevent smoke adherence? If the latter, why do people do it?

ETA to write more about humidity.... CA

Edited November 20, 2008 by chrisamirault (log)

[Dave the Cook]

A couple of definitions might help: in the McGee passage, what exactly do "surface" and "wet" mean?

[Chris Amirault]

And how thick is a "surface" exactly?

[SeanDirty]

Ok they mean moist surfaces as in how meat and proteins have "moist" surfaces, but lets say i just washed a piece of chicken it now has a Wet surface. Smoke forms a semi translucent layer which may or may not be invisible so if water is on the protein nothing is really stopping it from for example rolling off, and taking some of the smoke away from it...

Now that rolling off example may be a bit extreme but you get the point...

[MikeHartnett]

In smoking bacon (and butt, now that I think about it), I've actually never been patient enough to allow a pellicle to develop. I've always been quite pleased with the results, and I can't say that I'd want more smoke flavor than what I've gotten.

So now we have the two sides, each presented by those who haven't tried the other.

[Chris Amirault]

Oh, I've definitely done both, and pellicle wins over non-pellicle in terms of smoke flavoring. I don't think that the received wisdom is wrong. I just can't square it entirely with McGee.

I'm increasingly thinking that low-level humidity with a dried pellicle is the key here. Though I can't explain why.

[Chris Hennes]

What is the mechanism for smoke absorption? That is to say, as the particles of soot that make up the smoke drift past the sausage, what do they adhere to? Proteins? Water molecules? Fats? Any or all of the above? If they bond to water molecules, is it possible for a surface layer of bonded molecules to effectively form a barrier to further absorption?

[nickrey]

Perhaps my reading of the process was wrong but it seemed to me that the pellicle was more applicable to cold smoking when the item is not undergoing the chemical and physical changes created through cooking. I can't really see an advantage for items such as bacon whose surfaces would alter significantly once heat is applied.

[SeanDirty]

If you have ever touched smoke... It's kind of hard to explain but you will use the example of when I made smoked salsa fresca. The recipe called for smoking cherry tomatoes, as you can imagine tomatoes have a very slick repelent skin.

The process was similar to a double boiler, I used a deep hotel pan and a shallow preferated hotel pan, and a shallow solid hotel pan to cover. Obviously the tomatoes went in the peferated, and all of it went over a burner. Heat breaks down tomatoes fast! They will fall apart if left longer then a few minutes.

In that short time the smoke of the wood chips was able to impart quite a deep rich smokiness to the tomatoes. I noticed during the process that the smoke would leave a sticky film which was the smoke. The film was much like the glue left behind after you remove a sticker.

That may not be the best example, but it was a hard to get off flim. Anyways, you could imagine, the flim would stick to a dry surface more then it would a wet surface.

So to answer your question, it doesn't just stick to fat, and protein, but rather everything. As with a marinade, the flavor if left long enough would eventually penetrate deeper into the meat but before that it sticks to every exposed surface.

[Chris Hennes]

So to answer your question, it doesn't just stick to fat, and protein, but rather everything. As with a marinade, the flavor if left long enough would eventually penetrate deeper into the meat but before that it sticks to every exposed surface.

←

This is sort of what I am getting at: through what physical mechanism is the smoke "penetrating deeper into the meat"? Some particles of smoke are bonding to some particles of sausage, which are then moving through the meat towards the center. Is the purpose of the pellicle to facilitate this penetration? If so, how does it function? The smoke residue cakes on everything, pellicle or no, but how does it work its way inside?

[nickrey]

Found this in an article by Craig Goldwyn ( http://amazingribs.com ) thought it may add to the conversation. Original link for the article is http://knol.google.com/k/craig-goldwyn/mea...6escshr4kvt0/3#

It talks about the action of NO2 but one could reason that the same process of diffusion and absorption applies to other components of the smoke.

"Many smoked meats develop a smoke ring, a bright pink color just under the surface. Some people think the pink color means the meat is raw, but nothing could be further from the truth.

Nitrogen dioxide (NO2) is among the compounds formed in the high heat combustion of wood, charcoal, and even propane. As these compounds land on the surface of meat, especially cool moist meat from the fridge, some, including nitrogen dioxide, are moved deeper into the meat as cells lower in the smoke compounds pull them in with a diffusion and absorption process. The cells are simply seeking equilibrium... [the smoke ring occurs due to chemical changes in the NO2]"

edited to meet fair use policy

Edited November 22, 2008 by nickrey (log)

[HKDave]

OK, here's a theory: Could this be as simple as "oil and water don't mix"? Wood smoke is - judging by the creosote that builds up in the chimney - essentially oily, and also contains water vapour. So if the surface of the product to be smoked is wet, the smoke/oil is going to largely sit on top of the wet surface, at least until the heat and air flow of the process evaporates the water.

If the surface is dry - the 'pellicle' - smoke can bond with the dry meat immediately, and also, in the initial stages of smoking, the water vapour in the smoke is going to be attracted to that dry surface.

Makes any sense?

[dougal]

The first thing is to clarify what is meant by "smoking".

It means different processes to different people.

The steamy slow cooking of US 'BBQ' seems very different to, for example, the cold smoking of salmon, or the making of kippers.

Chemically, the flavour question must be whether the compounds that one wishes to capture from the smoke are soluble in water or fats.

Since 'cold smoking' was originally a preservation process, involving a considerable degree of drying, I'd venture to suggest that water-soluble compounds would be in a minority role. And a deliberately wet surface would be strange.

My guess would be that the pellicle has a relation to the salt-induced protein stickiness responsible for "the bind" in sausages. And that the stickiness would help the adherence of particulates from the smoke. Once bound, the aromatics in those particulates could diffuse through the food, whether oil or water soluble. However an excessively steamy atmosphere, promoting condensation on the food, would have the effect of washing off rather than trapping particulates...

I think it sounds as though McGee specifically is meaning only "US BBQ" when he writes there of the benefit of a wet surface for "smoking". That over-generalisation is a common difficulty for many lesser US-based authors!

The point of BBQ, seems to be to get very long, very slow cooking, without achieving (indeed deliberately avoiding) the intensity of smokiness found, for example, in a kipper. And if one is measuring the 'effectiveness' of the smoking by such measures as the fabled 'smoke ring', then indeed, wetting might prove more effective.

However, I believe the reverse to be the case for 'proper' smoking!

Edited November 21, 2008 by dougal (log)

[Chris Amirault]

We talked a bit about the "smoke ring" over here.

HKDave, I'm liking your explanation.

ETA: It still doesn't really explain McGee's comment exactly.

Edited November 21, 2008 by chrisamirault (log)