While it would be helpful to know:
- What kind of grill you currently have.
- What kind of smoker you're talking about acquiring.
I think I can still give you some decent feedback. Generally speaking, a smoker is better suited for cooking foods for a long time at a low temperature -- which is the traditional definition of "barbecue" in America -- than a grill would be. Conversely, a grill is better suited than a smoker for cooking foods at high temperatures over high, direct heat. This is not to say you can't cook on indirect heat using a grill, nor is it to say that some smokers can't be adapted for grilling. It's just which is the more suitable tool for what job.
For barbecue, a smoker offers the advantages of better heat control at lower temperatures, and greater food capacity in the cooking chamber.
I would suggest that if you want to do a lot of barbecue, particularly things that require really long cooking times (a pork butt or brisket can go as long as 14 hours), it would be worthwhile to get a smoker. If not, it would make more sense to adapt your grill for barbecue on the occasions that you would need it. Actually, I'd recommend you do that first, anyway, to see if you like doing that kind of cooking. An entry-level Weber smoker can run you $300, and I would not recommend going on the cheap with your smoker. The ones on the low end of the market do not work very well, and they will sour you on the concept.
Are there any systematical studies available?
I am not aware of any such study or resource, but ignorance of or lack of evidence of a thing doesn't necessarily mean that it doesn't exist.
Which spices can easily bear long durations of broiling, hot oven or barbecue?
Broiling is an especially intense cooking method, directly transferring energy to the surface of the target food by radiation. It also is not a method used for long cooking duration, because it is so rapid, and easily would burn or char the outside of the food.
As a general principle, hard, woody spices and hard seeds tend to be the most heat insensitive: black pepper, cinnamon, anise, nutmeg, cumin and so on.
In the herb family, the hardier herbs (bay leaf, oregano, and sage for example) can stand up to some prolonged cooking without adversely affecting their flavor.
Delicate herbs (cilantro, parsley, tarragon, basil for example) do not fare well as their flavors are very volatile.
Which lose flavor or deteriorate quickly?
See above; this is just a rephrasing of the same question.
Which develop displeasing flavors?
This is an open ended list question.
For a significant portion of the population, cilantro starts with a displeasing flavor.
Badly overcooked garlic can become bitter, if you consider it a spice. Similarly, paprika and many of the capsicum peppers become very unpleasantly bitter when burned.
Most flavors simply lose their intensity and become muted or difficult to perceive.
Which become unhealthy or even poisonous?
I am not aware of any.
What can be done to preserve sensitive spices during hot cooking?
Don't add them during prolonged cooking; add them at near the end of the cooking period or even after cooking is completed.
Best Answer
I like Ryan's idea because it adds moisture. The most common material I am aware of is 8″x8″ unglazed quarry tiles. UN-GLAZED is important!!! You don't want to add chemicals to your smoke. I have been off-set smoking for many years and plan to line my home built smoker with food grade fire bricks. Expensive but last forever.
I just found this link (not affiliated in any way) that might be useful. http://www.traditionaloven.com/articles/84/firebricks-heavy-dense-fire-clay-bricks
Another trick is getting used to controlling the airflow in your smoker. What I recommend is start off leaving the chimney (or vents on top) wide open and then use the intake (lower vents) to control the amount of air that is allowed to enter. The wider the opening, the more air and the hotter the fire. If you can't lower the temp with the intake, then close the top vents. It takes a little practice but once you can regulate the heat, your good to go.
Remember, thin blue smoke is what you're after.
Welcome to the sometimes frustrating world of smoking food. Patience and persistence (plus a beer or two) will go a long way.
Gringo Dave (first reply)