Explain about the Smoking - methods of food processing?

Smoking was known as a method of food preservation at an early date. Foods are exposed to smokes by burning some special kinds of wood. It has two main purposes, adding desired flavoring and preserving. In the earlier times, many households had smokehouses, which were used to smoke beef, ham and bacon. Smoking is still used to preserve fish and meat. Most meat is smoked after curing to aid their preservation. Preservative action is provided by such bactericidal chemicals in the smoke as formaldehyde and creosote, and by the dehydration that occurs in the smokehouse. The smoke is obtained by burning hickory or a similar wood like oak, maple, walnut and mahogany under low breeze/wind.