Science of Smoke
Smoke is created by the process of combustion. When you light a braai you are creating combustion, which is just the reaction of oxygen when it hits fuel, but combustion is what creates smoke. What you are looking at is a bunch of tiny particles floating around in a mixture of water vapor and gasses, a mixture of everything being burned. When wood burns it produces nitrogen dioxide, which hits the meat and dissolves losing its oxygen molecules. Once it loses its oxygen, it becomes acidic, and it tries to find something new to connect with to create more stability. What it finds in the meat is myoglobin, myoglobin attracts the acid and pulls it into the meat. Which is what makes the meat take on those delicious smoky flavours.
Ok, here goes - wood burns and that creates chemicals, some of those chemical's dissolve, what's left attaches itself to new chemicals found in the meat. The combination of chemicals in the smoke and in the meat are essential to smoking, too much nitrogen dioxide or smoke, and you will end up with a firestorm of note!
2. Why you want a good smoke?
Depending on the heat source, coal, wood or gas, the flavour profile of the smoke changes because each fuel source produces its own unique combination.
With that being said, the best smoke is almost invisible. A common amateur mistake is to create billowing white clouds of smoke. You're after a light blue smoke. Burning the right type of charcoal and following proper lightning and cooking methods will make or break your meal. The same goes for the type and amount of wood chunk or shavings you add. You need to use hardwood chunks or shavings for the best smoking flavour, like fruit and nut trees as softwoods usually contain more air and sap and cause a mixture of garbage that makes your food taste like, well, garbage. Remember that a little goes a long way and that what you are looking for when smoking is that magical light blue smoke coming out of your chimney once the fire has taken off and the coals in your smoker has settled – not a continuous mass of billowing white or even worse dark clouds of smoke.