Smoking and Barbequing Meat

[nathanm]

I have smoked and barbequed meats for many years, and I own, or have owned just about every device mankind has produced for doing this. This includes traditional style barbeque "pits" all the way to computer controlled smokers that control humidity temperature and a dozen other variables.

I don't mean to brag, but I've had some success at this - I've competed several times in barbeque championships, including Memphis in May and the Jack Daniels Invitational. The team I was on (I am not the leader however) has won first place at those competitions.

Along the way I have noticed the following things. First, nearly everybody involved in barbeque or smoking meat has strong opinions. Second, many of those strongly held opnions directly contradict one another! So, one guy will say "never do X", and almost certainly you can find somebody else that says "always do X". They can't both be right.

Often the opinions come with elaborate stories that sound semi-reasonable. However, in most cases these are like Kipling's "Just So" stories (how the leopard got his spots etc.) - they are based on folk wisdom, not reality. A famous example of this is the notion that you must sear meat to "seal in the juices". This makes a certain amount of intuitive sense - it just happens to be completely wrong. Barbeque and smoking are filled with these sort of beliefs, hence the directly contradictory "facts".

I am looking for some definitive answers and hard facts. I know people who are incredible barbeque chefs / pit tenders / smokehouse operators who fly by the seat of their pants. But surely in the 21st century some of these things can be reduced to fact. This is particularly true of parameters that must have been studied to death by food scientists, and the meat processing industry.

Some people viewing this post may question the importance of getting hard facts, because if the seat of the pants method works for you, why worry about things like relative humidity, or optimimum meat temperature? However, we have seen the same tranisiton occur in other forms of cooking as people test old beliefs and discover that many are false. New ideas, new techinques and a better understanding of cooking comes from such knowledge. So, even if you can't adjust your RH or wood temperatuer exactly, I think it is interesting to know what the real truth is.

Here is my initial list of questions to which I think there must be a definitive answer, but where there is seems to be no or little agreement.

In the questions below unless specified "meat" means flesh - i.e. poultry, pork, beef, fish.

1. At what temperature (in the meat) does meat absorb smoke best? One recent barbeque book claims that above 120F proteins in the meat start to set (which is true) and therefore no smoke can penetrate the meat (not necessarily true). He therefore recommends starting your meat as cold as possible, so it has the longest time to absorb smoke before the surface layer of the meat exceeds 120F. Other experts, including an award winning smoked meat producer I know, argue the opposite - they recommend adding smoke primarily at the end of the process, long after the meat temperature will exceed 120F. Note that this answer is likely to be slightly different for meat, poultry and fish since their proteins denature at different tempertaures. Note also that the optimum temperature for absorbing smoke flavor during the smoking process is likely to be quite unrelated to the final cooking temperature - i.e. when the meat is done.

2. What is the optimum temperature to generate smoke? There are many ways to generate smoke. One method uses an electric hot plate on which you dump sawdust, chips or pellets of hardwood - what temperature is the best for this? Other methods involve burning whole wood. A web page, from the University of Illinois meat science department says that the best quality smoke is produced between 650F and 750F. Below 575 they say the smoke is too acidic. Meanwhile, the manfacturer of a high end computer controlled smoking system told me the opposite - that you need to be below 575 to get low acid. Note that this temperature issue is related to the next question.

3. Does wet or moist wood make more or better smoke? Many people believe that you get the best smoke from having wood (sawdust, chips, chunks or logs) which are wet or damp. Note that I don't mean whether wood is green (i.e. freshly cut from a tree) or not - I mean the moisture content. Those in favor of wet / damp /moist wood usually advocate adding water, soaking the chips in water etc. Others argue just the opposite! Note that having moisture in the wood will lower the temperature at which it burns, so the advocates of using moist wood may actually be asking for lower temperature (the previous questoin). Moisture in the smoking wood would also contribute to the humidity - the next question. Humid smoke tends to be more opaque and light colored - as the smoke leaves the fire and hits the air, it cools down and reaches the dew point, creating droplets of water - i.e. like condensing steam does, or a fog or cloud. So, moist wood that produces humid smoke might LOOK more "smoky" but that does not make much difference. My guess is that moisture in the wood is actually irrelevant except insofar as it determins wood tempertature or humidity, but it would be good to know this for sure.

4. What is the optimimum humidity (RH) in the smoke chamber for smoking? Many smokers use water to add humidity to the smoking chamber - that includes both popular "water smokers" as well as fancy commercial units that have humidity control. Note that pans of water in the smoke chamber also help to control the temperature by absorbing heat and boiling, especially in uncontrolled wood burning pits or converted grills. Some people will tell you that humidity aids in smoke penetration, others will say the opposite. This page says that 30% to 38% RH is optimum, but does not say why. Note that I am asking about smoke penetration - at some point in the process of smoking or barbequing one typically wants to develop a "bark" or crust. This may require different conditions than the smoke penetration phase.

5. How much oxygen should there be in smoke production? Some people advocate a "smothered" or smoldering fire which is under-oxygenated. Such a fire (regardless whether it is on a tiny chip on a hot plate, or a whole log) tends to burn with dark sooty smoke. Other people advocate a clean burning fire with sufficient oxygen, pointing out that black soot particles do you no good in penetrating the meat. As with moisture content, the amount of oxygen can surely affect the temperature. So when people try to starve a fire of oxygen they might be trying to leave more unburned hydrocarbons in the smoke, or it might just be a round about method of controlling the temperature.

Note that I have steered clear of topics like "is dry rub better than wet rub?", because those are much more a matter of personal taste. It is clear that you can season meat any of several different ways, and deciding what is "best" is pretty subjective.

I am hoping that somebody on eGullet will have some pointers to definitive works on these topics or be able to answer with some hard facts.

Or add your own questions that need answers.

[project]

I like BBQ -- grew up in Memphis.

<br><br>

Chef G. Kunz and others have argued that quite generally in

cooking, it is good to emphasize salt, pepper, acid, and

sugar.

For more, they mention browning, smoke, and texture.

So, no wonder BBQ is good!

<br><br>

For your questions, just as you have asked them, I would be

surprised if the answers to very many of them are known at

all.

<br><br>

For a subject as complicated as cooking, getting really

thorough understanding is difficult.

Then, since cooking is also heavily practical, the lack of

precision and the contradictions you mention are nearly

inevitable.

<br><br>

For an easy way to 'resolve' the imprecision and

contradictions, given some procedure with a lot of rigid rules

from some expert, a procedure that results in good BBQ, just

observe that the procedure is sufficient for the

results and keep to oneself that the rules may not really

be necessary for the same results or even good results.

<br><br>

Some of your questions suggest that you have a 'methodology'

in mind: Identify the basic facts and, from them, construct

new procedures for good, even best, BBQ results. We could say

that you are attempting a case of 'reductionism' which had

some spectacular successes in parts of physical science,

engineering, and medical science. E.g., physics likes to

derive desired results directly from 'first principles'.

<br><br>

However, cooking is so complicated that using only

reductionism and derivations from first principles is not

promising. Then it is fortunate that people did well without

reductionism for millennia; it is not the only approach!

<br><br>

For 'best' and 'optimum', taken literally, in complicated

subjects these are often tricky goals. Typically we can get

some good results for reasonable effort; for more, it's

expensive; for still more, it's much more expensive, and we

get only a little more. We can encounter the 'law of

diminishing returns' so that the last tiny bit of improvement

for the best or the optimum costs more than all the rest of

the effort.

There is a famous profound question here called P versus NP --

for the first correct solution Clay Mathematics Institute will

award a prize of $1 million.

<br><br>

In a situation where the work to be done is clear enough and

the only consideration left is the cost, then finding how to

do the work for least cost or nearly so can be valuable in

practice. But, in many practical situations, there are many

criteria that have to be balanced. E.g., consider getting a

car with the smallest elapsed time in 1/4 mile acceleration:

As we get a car with elapsed time under 10 seconds, we have

something that is so specialized and so modified just for 1/4

mile acceleration that it is no longer useful for daily

transportation!

<br><br>

Sure, in a competition, achieving the best is crucial. But,

for a subject as complicated as cooking, or even just fresh

picnic pork shoulder BBQ at Memphis in May, understanding what

constitutes the 'best' in the minds of the judges will take

some effort!

<br><br>

As you likely know, there are books on smoking and curing

meats.

These may be of some help.

<br><br>

Right away I think of three views of your questions about BBQ:

<OL>

<LI>

Take a fresh picnic pork shoulder,

coat the cut surfaces with dry rub,

place on rack in pan in oven at

225 F until meat internal temperature is

about 195 F.

<br><br>

Then remove from oven, let cool to internal

temperature of 160 F,

separate putting meat in a 3 quart bowl

and discarding fat, skin, and bone,

coarsely chop meat,

pour over favorite purchased smoky BBQ sauce,

pile on especially large toasted white bread bun,

sprinkle on hot sauce, pile on creamy coleslaw,

add top of sandwich, and eat, with BBQ beans,

potato chips, and beer.

<br><br>

Dessert: Chocolate ice box pie.

<LI>

Do what you have done:

Get all information, equipment, advice,

experience, wood, charcoal, ingredients

possible for some years.

<br><br>

Then remove cooked meat from pit,

let cool to internal

temperature of 160 F,

separate putting meat in a 3 quart bowl

and discarding fat, skin, and bone,

coarsely chop meat, pour over favorite BBQ sauce,

pile on especially large toasted white bread bun,

sprinkle on hot sauce, pile on creamy coleslaw,

add top of sandwich, and eat, with BBQ beans,

potato chips, and beer.

<br><br>

Dessert: Chocolate ice box pie.

<LI>

From laboratory supply houses,

get sensors, transducers,

computer interfaces, and

computer software,

get a biochemistry laboratory

with spectrometry and chromatography,

get good with experimental design,

analysis of variance, and response surfaces,

get good with the applied mathematics of

optimization, stochastic processes,

and stochastic optimal control,

especially Pareto optimality in

multi-objective situations,

design, run, and analyze experiments.

<br><br>

Then remove cooked meat from pit,

let cool to internal temperature of 160 F,

separate putting meat in a 3 quart bowl

and discarding fat, skin, and bone,

coarsely chop meat, pour over favorite BBQ sauce,

pile on especially large toasted white bread bun,

sprinkle on hot sauce,

pile on creamy coleslaw,

add top of sandwich, and eat, with BBQ beans,

potato chips, and beer.

<br><br>

Dessert: Chocolate ice box pie.

</OL>

The results from the first view are really good, from the

second view, better, the third view, tough to wait that long!

<br><br>

In any case, the results are much improved by sharing with a

pretty young thing with a pony tail, circle pin, and poodle

skirt!

<br><br>

If the goal is to win the picnic pork shoulder competition for

the 2006 Memphis in May, then I would suggest starting with

understanding what the judges are looking for.

Then, work to give them what they are looking for.

This 'strategy' can be much more effective than just

trying to cook the best BBQ and then hoping that

the judges believe we have!

<br><br>

My guess would be:

The judges have a list of a dozen or so criteria.

To win, have to do well on all the criteria.

The main way to lose is to do poorly on one or more of the

criteria.

Actually getting (genuinely) optimum results on some

one criterion is likely not necessary or even very helpful.

<br><br>

The historical 'methodology' that gave us a lot of terrific

food was fairly simple and pragmatic, with a lot of trial and

error, a lot of superstition until we got some science,

insight based on a lot of experience, and incremental

improvements based on what did work so far.

So, optimality was not one of the goals or results.

<br><br>

It is true that careful experimental trials are one of the

most powerful approaches; also good, if only to guess what

to try next, is just the insight of someone with a lot of

experience.

<br><br>

Then, one of the early steps in some associated 'scientific'

work would be to take all that experience and observation and

identify, formulate, and describe what is fundamental -- e.g.,

guessing that those alpha particles were bumping into hard

dense nuclei at the centers of atoms.

For BBQ, we believe that some of the fundamentals are fat

melting, collagen melting, avoiding overheating the proteins,

etc.

<br><br>

For more, might look for university programs in meat

processing, get familiar with the literature they find important,

meet the people, and understand what is known. If you then

know enough for your goals, terrific. Else for more,

decide what questions to address next, selecting questions

you would like to have answered, you have a good chance of

answering, and, if you need funds, funding sources would

like to see answered.

[Shalmanese]

project, I'll have to respectfully disagree with nearly everything you have said here.

For your questions, just as you have asked them, I would be

surprised if the answers to very many of them are known at

all.

I would be disappointed but probably not surprised if these things have not been investigated. It's a testament to society that we probably know more about whats happening in the middle of a souffle than in the middle of a piece of smoked pork.

I'm almost certain the effects of water, temperature and oxygen on smoke production have been investigated though probably not in the context of food. I don't work in the field so you will have to wait for someone else to give some more specific cites. However, a quick google yielded this citation

The pyrolysis of several samples of sawdust of Fagus sylvatica L. wood with different moisture contents was carried out, keeping all other smoke generation parameters constant. However, parameters such as smoke production length and maximum temperature reached were affected by the moisture content of the sample and varied in the different pyrolytic runs. The acidity and the composition of the liquid smokes obtained were determined, this latter by means of gas chromatography/mass spectrometry and gas chromatography with flame ionization detection. The acidity and composition of the liquid smoke produced were affected not only by the moisture content of the sawdust sample but also by the smoke generation length and by the temperature of the process. The highest yields in components were produced from samples with low moisture content that underwent a short pyrolytic process. Some compounds, with important properties from an organoleptic and preservative point of view, were not generated from samples with high moisture content. Equations that closely relate yield of the total components or of groups of components or of individual components with parameters such as moisture content, length of the process, and temperature were obtained; these equations predict yield data of liquid smoke components with a satisfactory degree of approximation.

Emphasis mine.

Some of your questions suggest that you have a 'methodology'

in mind:  Identify the basic facts and, from them, construct

new procedures for good, even best, BBQ results.  We could say

that you are attempting a case of 'reductionism' which had

some spectacular successes in parts of physical science,

engineering, and medical science.  E.g., physics likes to

derive desired results directly from 'first principles'.

<br><br>

However, cooking is so complicated that using only

reductionism and derivations from first principles is not

promising.  Then it is fortunate that people did well without

reductionism for millennia; it is not the only approach!

I don't see how any of this applies to the questions asked. They largely stem from mechanical and chemical principles which, in theory, should be relatively easy to determine and control for. I would imagine that a reductionist approach would bring a straightforward answer to nearly all of the questions.

Nobody is suggesting that answering these questions will automatically allow the most clueless person to produce perfect barbeque. No more than saying that a solid grounding in paint mixing, colour theory or perspective will make you a brilliant artist. But such knowledge is undeniably scientific and "reductionist" in nature and acts as an aid rather than a replacement to barbeque talent.

For 'best' and 'optimum', taken literally, in complicated

subjects these are often tricky goals.  Typically we can get

some good results for reasonable effort; for more, it's

expensive; for still more, it's much more expensive, and we

get only a little more.  We can encounter the 'law of

diminishing returns' so that the last tiny bit of improvement

for the best or the optimum costs more than all the rest of

the effort.

I don't see where the diminishing returns comes into play. It's not harder to soak chips or not soak chips and if your committed to staying at a constant temperature, I don't see how it's any more effort to stay at the optimum temperature.

There is a famous profound question here called P versus NP --

for the first correct solution Clay Mathematics Institute will

award a prize of $1 million.

P vs NP has nothing to do with this situation.

In a situation where the work to be done is clear enough and

the only consideration left is the cost, then finding how to

do the work for least cost or nearly so can be valuable in

practice.  But, in many practical situations, there are many

criteria that have to be balanced.  E.g., consider getting a

car with the smallest elapsed time in 1/4 mile acceleration:

As we get a car with elapsed time under 10 seconds, we have

something that is so specialized and so modified just for 1/4

mile acceleration that it is no longer useful for daily

transportation!

Yes, but nathanm *is* competing in what is the equivilant of the race car competition where a reduction of a few milliseconds counts. Even for the rest of us, maybe we are never in a situation where such matters are crucial, but it would still be good to know such things.

From laboratory supply houses,

get sensors, transducers,

computer interfaces, and

computer software,

get a biochemistry laboratory

with spectrometry and chromatography,

get good with experimental design,

analysis of variance, and response surfaces,

get good with the applied mathematics of

optimization, stochastic processes,

and stochastic optimal control,

especially Pareto optimality in

multi-objective situations,

design, run, and analyze experiments.

<br><br>

Then remove cooked meat from pit,

let cool to internal temperature of 160 F,

separate putting meat in a 3 quart bowl

and discarding fat, skin, and bone,

coarsely chop meat, pour over favorite BBQ sauce,

pile on especially large toasted white bread bun,

sprinkle on hot sauce,

pile on creamy coleslaw,

add top of sandwich, and eat, with BBQ beans,

potato chips, and beer.

<br><br>

Dessert:  Chocolate ice box pie.

</OL>

The results from the first view are really good, from the

second view, better, the third view, tough to wait that long!

Except we only ever need to do the 3rd once. Then we can share the results with the world and add it to the sum of human knowledge. And we don't need any of the stuff you mentioned above if you get right down to it, just good old double blind taste testing.

Unfortunately, nathanm, I don't know the answer to any of these questions but I would be equally fascinated to know. Why don't you start answering them yourself by testing some of those theories?

[woodburner]

i'm certainly no expert, food scientist, rocket scientist, you get the picture but here is my take,

Starting with question number one, I have a few thoughts and maybe facts.

Smoke rings as they are commonly called in the barbeque world are a temperature dependent reaction. Bacteria are needed to change the nitrates to nitrites. Bacteria are active between 40 and 140 degrees F. Once the meat reaches 140F, the ring formation stops. So to maximize the extent of the smoke ring, put the meat on right out of the refrigerator and start out cooking at a lower temperature. Also, above 140F proteins start to denature and the myoglobin is no longer available. With small cuts, like baby back ribs, the smoke ring will go all the way through. Heavier smoke early on will affect the depth and intensity of the smoke flavor meat. While the smoke ring may stop formation at or about 140ºf meat, fish or muscle will contiue to take on smoke. without the formation or if you will, penetration.

Wive's tale number one is that muscle or flesh will no longer take smoke after 140ºf. Pour on smoke, well after that number and I bet you can taste it. In my opinion it will be acrid.

woodburner

[nathanm]

Like I said, there are many strong opinions, often contradictory

While one can cook by the seat of the pants and get great results and then have chocolate ice box pie for dessert. Be my guest.

However I like to understand more about the process. Sometimes that means using sensors and transducers and so forth. The knowledeg that is learned that way can have a lot of implications, even for seat of the pants cooking. But anyway, that is what I am interested in.

As to the other post, I don't think that bacteria are responsible for the smoke ring - or anyway I have never heard that, and would be shocked if it was so.

[mharpo]

Like I said, there are many strong opinions, often contradictory 

While one can cook by the seat of the pants and get great results and then have chocolate ice box pie for dessert.  Be my guest. 

However I like to understand more about the process.  Sometimes that means using sensors and transducers and so forth.  The knowledeg that is learned that way can have a lot of implications, even for seat of the pants cooking.  But anyway, that is what I am interested in.

As to the other post, I don't think that bacteria are responsible for the smoke ring - or anyway I have never heard that, and would be shocked if it was so.

←

The bacteria thing seems highly suspect to me too.

I am a seat of the pants BBQ'r with a fair amount of experience and I can tell you that IMO unsoaked wood provides a better quality smoke than soaked wood. It's my understanding that soaked wood will not burn efficiently- duh. Also, I find that burning hickory with the bark on will produce an acrid flavor. Also, it is important to have good airflow through your smoker for better tasting smoke. If you close the damper you'll get stale smoke with an off flavor.

As for when to add smoke, I don't know if it matters that much. Many times I start BB ribs in the oven at 200 - 225 for a couple of hours and finish in my smoker (New Braunfels with firebox) and there is plenty of smoke flavor in the meat. And, I get the desired color I'm looking for. Also, IMO, over smoked meat is not desirable.

Just my $.02

Edited August 1, 2005 by mharpo (log)

[ianeccleston]

According to Harold McGee, the authority on the science of cooking, the smoke ring is not made by smoke, but from the interaction of proteins, enzymes, and such. When I get home I'll quote him directly if I'm allowed to by copywright laws.

Ian

[BigboyDan]

Uhhh, a little too much knowledge can be a dangerous thing. Part of the greatness of barbeque (especially Central Texas brisket and hot link sausage) is due to all the trial and error that has gone before without knowing what's going on scientifically. Barbeque should remain an art. Every part of the country has its unique BBQ heritage based on so many connected factors due to its particular location, product availability, and cultural personality. Each piece of meat is different, the pit is different each day, the temperatue, the humidity, the mood of the pit master, all different each day. Even the process of eating BBQ, the choice of sides and drink, all different, all a result of decades of natural evolution.

Picasso once said that he had no clue as to why he was a great painter, and as to why others thought the same...

Dan, from Austin

[Doc-G]

Hi Dan and Everyone else,

You mentioned that 'too much knowledge can be a dangerous thing' and that BBQ should remain an 'art'. I would argue that having this knowledge will only improve the consistency of which you can produce these beautiful products that are made in these BBQ's. I therefore have to respectfully disagree with you on this topic. You mention that each piece of meat is different with different moods of pit masters etc...

Whilst this may be of benefit to cause differentiation across different regions or between one pit master and the next, a proper appreciation of the reactions involved and a truly developed methodology will allow the individual pit master to create and re-create the same results every time, all the time.

I gather this is what interests NathanM. Having this knowledge enables you to create consistency with your product. Having consistency also means that you have control and when you have control you are able to further refine your technique so that you will be able to easily define the changes in your product caused by changes in your technique.

Doc-G

Edited August 2, 2005 by Doc-G (log)

[nathanm]

As I said in the original post, I have great respect for "seat of the pants" barbeque. There is no disrepect to this approach in wanting to learn more, nor does it take anything away from that to actually find out how it works. If you want to still make barbeque your way, nobody will stop you - certainly not me.

[DTBarton]

In my experience, I've found that with respect to wood, larger pieces or chunks don't need to be soaked, but they need to be pre burned or started slowly to prevent too much "raw" smoke from tainting the flavor and color of the meat. This is why you see many pit cookers shoveling already burning wood in to their pits. Chips, which I use for items that are cooked more quickly in a hotter grill (like barbecued chicken, total grill time 60 - 90 minutes depending on size) seem to me to work better soaked, they burn away too quick and hot if you put them on the fire dry.

I've started meats (mostly ribs and shoulders) from cold and from nearer room temp and not noticed a huge difference in smoke absorption (flavor or color).

I must say, the first few posters in this thread get kudos for the length and breadth of their posts!

[jackal10]

By smoking I assume you refer to US barbeque style of hot smoke cooking, rather than cold smoking, for example of bacon, hams or salmon to make lox.

I'm no expert, but I do have some pyrotechnic as well as culinary experience. It seems to me that we need to distinguish between several processes going on simultaneously.

a) Complex physical and chemical processes in the pyrolysis of the wood produce many chemicals in the smoke, whose composition changes with time as the fire and smoker heats;

b) Smoke flavours condense on the surface of the meat, and may dissolve in the moisture or fat there

c) The flavours permeate the meat by diffusion (and maybe osmotic) processes

d) Water, and some other volatiles evaporate from the surface

e) The temperature of the meat rises, with associated effects of protein and collagen degradation.

Applying to your questions

1. What temperature does the meat adsorb the smoke best?

I suspect it is more about time then temperature. Cold smoked meats are typically smoked at below 90F for days, and then the smoke flavour continues to migrate in while they mature over months. Herve This, and many others, including NMR studies by my colleague Prof. Laurie Hall at HSLMC here in Cambridge have shown that flavour (and brine) penetration is very slow. The "smoke ring", formation of Nitro-myoglobin and other nitro compounds only penetrates a short distance into the meat.

Colder meat will also allow more and lighter volatiles to condense. However creosote and other "bad" flavours will condense as well.

Smoke added at the end will deposit more volatiles, and so give a a different flavour profile to the surface than smoke flavour deposited early in the process, some of which will be adsorbed and some re-volatized as the temperature rises.

There is an interaction with the fire and smoker temperature here as well, since the fire temperature will also govern the flavour and volatile profiles in the smoke and deposited on the meat.

2. What is the optimum temperature to generate smoke?

Pyrolysis of wood is complex has been studied, for example

http://www.fpl.fs.fed.us/documnts/fplrp/fplrp130.pdf

http://www.stanford.edu/~sanjiv/papers/sesi-review.pdf (use the Google HTML

cache)

"The overall process of pyrolysis of wood is believed to proceed as follows [6]. At around 160C the removal of all moisture (dehydration) is complete.

Over the temperature range 200C to 280C, all the hemicellulose decomposes, yielding predominantly volatile products such as carbon dioxide, carbon monoxide and condensable vapours. From 280C to 500C the decomposition of cellulose picks up and reaches a peak around 320C. The products are again predominantly volatiles. The decomposition rate of lignin increases rapidly at temperatures beyond 320C. This is accompanied by a comparatively rapid increase in the carbon content of the residual solid material. Thus, thermal decomposition of cellulosic materials such as wood proceeds through a complex series of chemical reactions, coupled with heat and mass transfer processes. Emmons and Atreya [7] estimate that over 200 intermediate products are formed during the pyrolysis of biomass. Roberts [6] puts the number of products at over 100. Since cellulose is the major constituent of wood and pyrolyses over almost the entire range of temperature, several researchers have studied pyrolysis in detail, in order to understand the mechanism of pyrolysis of wood."

The rate of heating affects the chemical composition of the volatile products, as does secondary pyrolytic reactions, the further decomposition of the primary pyrolitic products. These depend on the physical characteristics of the wood - particle size, for example, and whether the primary products condense in the wood mass or the char or escape.

The literature would suggest that temperatures below 300C/572F where the decomposition is primarily that of hemicellulose give rise to less tar and acid, but it is not definitive.

3. Does wet or moist wood give more or better smoke?

Your point about additional steam appearing to give more smoke is well made.

However I suspect water content was used to control the temperature of the fire, and to reduce flame - the secondary burning of volatalised hydrocarbons.

4. What is the optimum humidity?

There is a balance between keeping the surface moist to both keep the meat moist and to allow the aqueous soluble components of the smoke flavour to dissolve and penetrate, and to then dry the surface to form the "bark".

It may be that the optimum humidity should change throughout the process.

Initially moist (boiling water pans would be close to 100% humidity), then drying out during the last stages (water pan boils dry), then wet again to add the final volatile components.

d) How much oxygen should be used in smoke production?

Pyrolysis is not primarily an oxidation process. The oxygen level mainly affects the burning of the carbon char to carbon monoxide or dioxide, and the burning of the volatile secondary products. Since that is highly exothermic, it affects the temperature and speed of the pyrolysis reaction.

The level of draft also affects the speed of transport and the dwell time of the volatile products from the fire to the meat.

As with all these things, one variable, such as the wetness of the wood, or the amount of draft affects many different processes. It is the skill of the pit tender that they can use their skill to act as part of the feed back loop to optimize conditions, and so get the right sort of volatiles produced and condensed onto the meat from comparatively crude equipment.

Just as sous-vide and similar long time low temperature cooking has transformed the cooking of roast meats by separating the cooking and the browning of the surface steps, I would heretically suggest separating the flavouring and cooking processes.

First cold smoke (<90F) the meat to the desired degree of smokiness. Cold smoke allows good control of the volatile flavour components, and time for them to penetrate the meat. I use dry oak sawdust, or cherry for a sweeter smoke. Then, at your leisure cook sous-vide or in a low temperature oven to the desired texture - I guess the traditional 180F, past the collagen plateau, to allow conversion to gelatin, although I suspect the plateau phenomenon is more to do with the melting of fat.

Of course this two stage method misses out on the romance of a traditional pit belching smoke, but it may be more controllable.

May even need three stages - smoke, sous-vide cook, then finish the surface (blowtorch/hot smoke).

Edited August 2, 2005 by jackal10 (log)

[Varmint]

May even need three stages - smoke, sous-vide cook, then finish the surface (blowtorch/hot smoke).

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Hmmm, I'm going to need a huge bag and water bath to do a whole hog sous-vide!