Dirty smoke is a problem that everyone who operates a smoker will encounter sooner or later. Charcoal smokers are much more likely to produce dirty smoke than pellet smokers, and adjusting the smoker to prevent dirty smoke is different for both.
The biggest reason that you should avoid dirty smoke is that it causes your meat to get a gross, acidic flavor that carries a high risk of carcinogens. Eating smoked brisket or chicken that makes your lips tingle and smells like a campfire shows it was cooked with dirty smoke.
What Color Should Smoke Be When Smoking Meat?
If you have watched a smoking competition, you'll notice very little smoke coming from the top vent. What smoke you do see is a pale blue smoke that quickly disperses. Wispy, thin blue smoke indicates that the fire is burning at the correct temperature and that the fuel is good quality. Thick, white smoke, black smoke, or smoke with visible soot are indications of a problem with the fuel, the airflow, or the temperature.
What Causes Dirty Smoke
Dirty smoke is caused by a fire that is not burning well. The visible smoke is the result of components of the wood that have not completely combusted. The particles are exhausted as waste from the smoldering fire and stick to your meat on the way out of the smoker.
Meat exposed to dirty smoke for a short period of time may not exhibit any acrid flavors, but it won't take a long time before the meat starts to get a nasty coating of dirty, burned chemicals. Avoiding dirty smoke requires understanding what causes bad smoke to form in the first place.
What is Dirty Smoke?
Smoke is composed of gasses, solids, and liquids – and each contributes to the flavor of your meat. A properly burning fire using wood that is appropriate for smoking will release aromatic compounds so the smoke leaves the meat with a delicious flavor. Dirty smoke causes acrid flavors because the compounds in the smoke never reach high enough temperatures to allow for desirable chemical compounds to form.
Causes of Dirty Smoke in a Pellet Grill
Pellet grills offer many benefits to simplify the smoking process. Among the benefits is the reduced chance of dealing with dirty smoke. A properly functioning pellet smoker will maintain a firebox temperature that keeps dirty smoke from forming. When the smoker isn't working correctly, it can create dirty smoke.
The primary issue with a pellet smoker that causes dirty smoke is failures in the auger feed system or the fans. When pellets are feeding too slowly or inconsistently, the fire will fluctuate from a good burning fire to a smoldering fire, leading to improperly burned pellets and off-flavors on your food.
If you are getting dirty smoke from a pellet smoker, you should check to make sure that the feed system and fans are functioning correctly. Proper airflow is critical to maintaining the proper temperature in your smoker.
The most common reason that a pellet grill will exhibit dirty smoke is due to poor-quality pellets. Pellets that have been exposed to moisture are likely to smolder and produce thick white or grey smoke. You should never use pellets that have gotten wet because they will not burn consistently and will cause temperature spikes and dirty smoke.
Low-quality pellets can also cause dirty smoke because of an incomplete combustion process. Pellets that have too much dust or are made from low-quality materials produce smoke that can leave acrid flavors. Always use pellets from a company you trust. We have had success with Traeger-brand pellets, and they are our go-to when we are smoking meat on our Traeger 885.
Causes of Dirty Smoke When Using a Charcoal Smoker
Whether you are using a Big Green Egg or an offset smoker, you are going to deal with dirty smoke at some point. Quality cooking materials matter, so you should choose the highest-quality lump charcoal and kiln-dried hardwood when smoking meat with a charcoal smoker.
Problems that cause dirty smoke can begin from the moment you start your charcoal smoker. One common cause of dirty smoke is when unlit charcoal is lit in the smoker. You will notice that the first smoke is thick white smoke. Thick white smoke is dirty smoke and is caused by moisture evaporating from the surface of the charcoal or wood.
After 10 to 15 minutes, the white smoke should subside, and you will be left with a clean-burning fire. An easy solution to white smoke is lighting lump charcoal in a chimney starter and add it to the firebox once the charcoal has a grey appearance and is no longer emitting dirty smoke.
For many years, it was common practice to soak hardwood chips in water before using them in the smoker. The idea was that the moisture would prevent combustion from happening too quickly, giving the wood chips a chance to ignite and smolder without catching fire.
We know now that this is actually counterproductive to producing a good fire. As the moisture evaporates, it cools the smoker and the wood, causing dirty smoke. Wet wood chips will cause gray smoke, much like you will see when brush or trees catch fire.
In the same way, you want to avoid using green wood in your smoker. The moisture in the wood will evaporate, leading to unstable temperatures and billowing smoke. Even dry wood that has aged will emit dirty smoke, and for this reason, we suggest that you only use hardwoods that have been kiln-dried and properly stored to prevent moisture damage.
The most common issue that causes dirty smoke from charcoal smokers is improper venting which does not allow enough oxygen for full combustion. The tendency is to close down the vents as much as possible to control temperatures, but this might not allow enough air. As the airflow is reduced, the fire is slowly smothered, which creates dirty smoke.
We have found that setting the bottom vent to between 30 and 60 percent open and using the top vent to find the sweet spot. More air from the inlet will provide a higher temperature in the firebox that will fully burn wood or charcoal.
A better way to control temperatures in charcoal grills like the Weber Smokey Mountain is to keep the fire small. Too much wood burns too hot and can cause unstable temperatures. Another issue when loading too much fuel is that the unlit wood will smolder and cause dirty smoke and an acrid taste. Our method is to build a coal bed that gets the coal bed hot enough, then add smaller pieces of seasoned wood to the hot coals. Burning wood on a hot fire produces good smoked meat.
How to Get Perfect Thin Blue Smoke Every Time
We have perfected the art of starting and maintaining a fire so that it offers complete combustion, good smoke, and delicious flavors. Here are some tips that will help prevent problems.
Start with a Hot Coal Bed
We have found that when we start our charcoal smoker, letting the first batch of coals burn very well before adding meat to the smoker will start the process out on the right foot. Our process is to fill the chimney and place it in the firebox, then refill the charcoal chimney starter. We light the chimney outside of the smoker and let the coals burn until they are gray and ashy, then add the coals to the firebox.
After about 15 minutes, the unlit coals will have ignited and should be burning nicely without producing white or gray smoke. We typically let the smoker get quite hot during the process, then use the top vent to slowly bring the temperature down until we are at the target temp and producing good, thin blue smoke from the exhaust vent.
The Minion Method
A similar approach was developed by pitmaster Jim Minion using a Weber Smokey Mountain grill. This method also is effective in a Big Green Egg for maintaining a long, slow smoke without having to add charcoal. Unlit charcoal is arranged in a ring around the outside of the charcoal basket. Prelit charcoal is added to the center, along with smoking wood. As the coals burn, they slowly ignite the unlit charcoal. The unique shape of these grills allows the charcoal to complete combustion without creating white smoke.
Use an Appropriate Fuel Source
You should never use charcoal briquettes, treated lumber, or dry wood that hasn't been kiln-dried in your smoker. These wood products will produce heavy white smoke from water vapor and could introduce any number of volatile and harmful chemicals. Start burning good, clean, dry wood and you'll have the right fire for smoking meat.
Maintaining a Clean Smoke
Now that the coal bed is good and hot, we add the kiln-dried hardwood or fruitwood we are using. We add small pieces at a time to prevent smothering the coals. A hot coal bed will quickly ignite the wood and start producing a smoky flavor without thick smoke. You should have a thin blue smoke coming from the exhaust vent.
As the smoking wood burns, it becomes coal and adds to the coal bed. In this way, you are adding smoke flavor, then fuel, then more smoke flavor when you add more smoking wood. Sometimes, you will need to add more coals to maintain the coal bed, particularly when smoking larger cuts of meat like brisket that require a long smoke. Always start new charcoal in a chimney before adding it to the smoker to prevent white smoke.
Other Ways to Avoid Dirty Smoke and Other Contaminants
One of the ways you can make sure that your smoker will produce clean smoke is by keeping your smoker clean. Grimy grill grates, soot-coated smoker walls, and built-up ash in the firebox can all contribute to unhealthy smoke. When carbonized food, soot, and ash are heated, a variety of toxic chemicals are released into the smoke. This is why smoked meat in a dirty smoker makes the food taste like an ashtray.
Why Thin Blue Smoke is Good
We smoke meat to produce that special smoke flavor, and the only way to get the flavor right is with a good smoke. A fire that produces clean smoke allows nitric oxide and carbon monoxide to interact with the myoglobin in the meat. The chemical and physical reaction that happens results in the smoke ring you see when slicing into a cut of meat.
Other flavor compounds are created at high temperatures that give meat unique flavors depending on the type of wood. You should be able to tell the difference between hickory, oak, and applewood when you smoke meat. If you can't, it is because you are not producing thin blue smoke and high enough temperatures while smoking meat.
Clean smoke will provide the right condition to create crunchy bark that is red or dark brown – also the result of myoglobin interacting with smoke. White smoke tends to blacken meat and does not make a nice bark.
The key thing to keep in mind when trying to get perfect blue smoke is that the process begins before you start smoking meat. You will want to start with a clean grill and use an appropriate method to start burning wood and making clean smoke. Incomplete combustion causes unhealthy smoke because the wood is producing harmful chemicals while burning wood.
Always use high-quality lump charcoal and kiln-dried hardwood in your smoker to get ideal blue smoke and perfect smoky flavor the next time you are smoking ribs or butt roast.
The most challenging part of the process is learning how to manage the vents on your smoker properly. It will take practice to find the sweet spot where your fire gets hot enough and produces thin blue smoke without letting the smoker's temperature go out of control.
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