Big Green Egg - EGGhead Forum - The Ultimate Cooking Experience...
Welcome to the EGGhead Forum - a great place to visit and packed with tips and EGGspert advice! You can also join the conversation and get more information and amazing kamado recipes by following Big Green Egg at:

Want to see how the EGG is made? Click to Watch

Facebook  |  Twitter  |  Instagram  |  Pinterest  |  Youtube  |  Vimeo
Share your photos by tagging us and using the hashtag #BigGreenEgg.

VOC

Im a little confused on this VOC deal.  I understand that after you light a new load of lump that you should let it burn until the smoak clears, turnes light blue, indicating that the VOC's have burned off.  My question is if your doing a low and slow and you only light one small portion of the load of lump then will you ever burn all of the VOC's off since the fire esentialy moves around the load of lump as it burns?

Comments

  • SkiddymarkerSkiddymarker Posts: 8,522
    It is based on temp being above 225º or so, I think. In other words as the firebox heats up the VOCs will gas off - at least that's the way it was explained to me. During the cook, there may be more, they are just not as intense as the first 10-15 minutes of the cook. 
    Delta B.C. - Whiskey and steak, because no good story ever started with someone having a salad!
  • SardonicusSardonicus Posts: 1,700
    edited May 2015

    That's a great question.  I'll give it a shot, though there are many here who can give you a more scientificky answer.

    It isn't so much that the flame is 'burning off' the VOCs as that the clear smoke indicates that the affected lump is no longer emitting the VOCs.

    Even though the other lump has yet to burn, VOCs are nonetheless being shed.  In fact, it is my understanding that you could just leave lump sitting on a table and VOC concentrations would gradually dissipate.

    You've probably noticed that even with a low & slow cook that's started in one spot, the smoke doesn't revert to "bad" as the fire spreads.  That's because the VOCs were scramming even as the initial spot burned.

    "Too bad all the people who know how to run the country are busy driving cabs and barbecuing."     
     - George Burns

  • DMWDMW Posts: 13,832
    Here's the best explanation I've seen, from @stike

    "VOCs aren't simply trapped in the charcoal and only allowed to escape when they burn.  the vast majority of them will evaporate (that's the 'volatile' part of the equation in this case) simply by being exposed to the draft and having the additional heat from the fire drive them out.

    if you never lit the fire, and simply induced a draft through the egg, you'd air out quite a bit of the VOCs.  as your egg is coming up to temp, there's a constant draft, and building heat.  the heat makes the compounds even more volatile, and they readily evaporate. by the time you reach stable smoking temps, say an hour later, you will have blown off most of the VOCs.  what little is left is insignificant.  the fire for a 250 degree cook is minimal

    open a bag of fresh charcoal and smell it.  that fume-iness is the VOCs.

    in this case, 'volatile' doesn't mean flammable, it means that it readily forms vapor.  perfume is 'volatile', for example, whether or not it is actually flammable"

    http://eggheadforum.com/discussion/1138028/burning-off-the-vocs-for-a-low-and-slow
    They/Them
    Morgantown, PA

    XL BGE - S BGE - KJ Jr - HB Legacy - BS Pizza Oven - 30" Firepit - King Kooker Fryer -  PR72T - WSJ - BS 17" Griddle - XXL BGE  - BS SS36" Griddle - 2 Burner Gasser - Pellet Smoker
  • stlcharcoalstlcharcoal Posts: 4,553

    VOC's are smoke.  If you're going to smoke something, no reason to burn the smoke off unless you really have something delicate/expensive that you must to control the flavor & intensity (fish, poultry, etc.)  In that case you're kind of screwed because you're going to have to get it hot enough to get the fire to spread, then it's going to be too hot to low & slow.  You would need to fire it up, get it ripping until the smoke burns clear, shut it down, let it cool, then start all over again with your smoke woods......but then if you want to top off the charcoal, now it's going to smoke again.

    Way to combat all this, use a charcoal that has a high carbon content and is made with domestic hardwoods (since that's what you're going to be smoking with anyway.)

    Don't get scared of the word "VOC", it's not radioactive or poisonous gas......it's just the wood that's left in the charcoal burning off.


  • YukonRonYukonRon Posts: 16,792
    VOC is defined as a Volatile Organic Compound. These compounds must contain at least one carbon atom and/or one of the following atoms: hydrogen, oxygen or nitrogen, as defined by the Clean Air Act of 1970, which entailed a multiple directional approach to providing clean air, as required in our constitution. By this very definition, water is a VOC. It is somewhat confusing, as organic implies the requirement for carbon to be in the compound. So, when we look at VOC, the temperatures we have typically is enough for these atoms, excluding carbon to evaporate. Temperature needs to be much higher to release carbon, and carbon is the smoke, or particulate contaminate in breathable air. The volatiles disperse rapidly, and the smoke we need for flavor, lingers a bit longer for us to use, or not.

    "Knowledge is Good" - Emil Faber

    XL and MM
    Louisville, Kentucky
  • stlcharcoalstlcharcoal Posts: 4,553
    edited May 2015

    Our charcoal is kilned at 1200-1500F, it burned off long ago.

    Like I said in the other thread, "VOC's" have morphed into something else on this forum.

  • YukonRonYukonRon Posts: 16,792

    Our charcoal is kilned at 1200-1500F, it burned off long ago.

    Like I said in the other thread, "VOC's" have morphed into something else on this forum.

    Amen
    "Knowledge is Good" - Emil Faber

    XL and MM
    Louisville, Kentucky
  • TheophanTheophan Posts: 2,654

    VOC's are smoke.... Don't get scared of the word "VOC", it's not radioactive or poisonous gas......it's just the wood that's left in the charcoal burning off.

    Two things:

    First, volatile organic compounds proven to be emitted from charcoal cooking include benzene, toluene, ethyl benzene, meta para xylene and styrene. Formaldehyde and acetaldehyde and other carbonyl compounds are also found in charcoal cooking.  These things are potentially poisonous.

    Second, whether it has to do with VOCs or not, very many people observe a thick white smoke when new charcoal (even with no wood chips or chunks) is beginning to burn that has a different smell, and flavors the food differently, than the clear blue smoke that is observed after 20 minutes or so.  Maybe your own experience is different, and by all means cook the way that works for you!  But VOCs or no VOCs, many people find that they like the way their food tastes better if they wait till that thick white smoke is gone before they put the food in the Egg.
  • stlcharcoalstlcharcoal Posts: 4,553
    edited May 2015
    Theophan said:
     

    Two things:

    First, volatile organic compounds proven to be emitted from charcoal cooking include benzene, toluene, ethyl benzene, meta para xylene and styrene. Formaldehyde and acetaldehyde and other carbonyl compounds are also found in charcoal cooking.  These things are potentially poisonous.


    I have read this report before, and if YOU read the report....THEY ARE BRIQUETTES!!!! 

    Manufacturers use hardwoods such as beech, birch, hard maple, hickory, and oak as well as softwoods including long leaf and slash pine, nutshells, and fruit pits. They also use vegetable wastes, paper mill residues, sawdust and woodscraps from lumber mills, and old household furniture combined with binding agents for holding their shapes [26]. However, many commercially available brands are also known to contain poten-tially harmful ingredients, including coal dust (as a heat source),sodium nitrate (to aid ignition), and VOC-forming lighter fluid forquick-light brands 

    So, there are your poisonous gases.  Even if they're not using the wastes, the anthracite can be some nasty stuff. 

    Even if it was lump, god knows what those trees were subjected to with pollution and hazardous materials.  Then they're put in beehive kilns at low temps.  If we made lump at low temps (below 700-800F), heavy metals would probably show up in the samples.

  • EggHead_BubbaEggHead_Bubba Posts: 566
    @stlcharcoal... lump school is in session. Very much appreciate your knowledge and willingness to share it. I'm a recent convert from Royal Oak to Rockwood, will never look back and not worry about "VOCs". =)

    Rocky Top, TN — Large BGE • Cast Iron Grate & Platesetter • Rockwood Lump

  • stlcharcoalstlcharcoal Posts: 4,553
    @stlcharcoal... lump school is in session. Very much appreciate your knowledge and willingness to share it. I'm a recent convert from Royal Oak to Rockwood, will never look back and not worry about "VOCs". =)

    Thanks.  Not saying our charcoal doesn't contain some sort of "VOC", but not the variety that the other crap does.  "VOC" is kind of a catch-all term and this forum has pretty much adopted the thought that anytime you see smoke from a charcoal, it's some nasty chemical burning off.  All charcoal's are not created the same--as evidence, the report about Chinese briquettes......surprise, surprise. 
  • YukonRonYukonRon Posts: 16,792
    Different compounds have different evaporation rates. Add temperature and elevation, the rate changes. Most of the compounds mentioned above have a relatively low temperature where they begin evaporation. Not really sure on the exact numbers, but those who use briquettes for very low smoke, such as cheese, would seemingly be most at risk. Accelerants burn off fast, but of course concentration of the compound must also be understood. 
    Lump charcoal, in the manner to which it is processed, has a distinct advantage over any briquettes, period.
    RW is a very high quality product. I have 10 bags on hand. There are others out there that are good. Do your research, find what works for you. I do not think I will use briquettes again on my own choosing, those days are gone for me.
    "Knowledge is Good" - Emil Faber

    XL and MM
    Louisville, Kentucky
Sign In or Register to comment.
Click here for Forum Use Guidelines.