TOBACCO CURING PRACTICES
After harvesting tobacco, growers “cure” it using air, sun, heat and/or fire. Curing tobacco enhances the leaf’s natural flavor and reduces its moisture content, allowing it to be stored for extended periods. Some curing methods use natural heat sources like the sun, while others require fuel such as wood.
According to the International Tobacco Growers Association, there are four main methods of curing:
| Air curing depends largely on natural variations in air temperature and humidity to achieve the desired result. This method typically is used for burley and dark air-cured tobacco products. | 
| Sun curing dries tobacco leaves in the sun. This method typically is used in oriental tobacco products. |
| Fire curing uses exposure to wood smoke to produce a dark, smoky leaf. This method is used for dark-fired tobacco products. | 
| Flue curing uses an external heat source and flue system to circulate heated air among harvested leaves. This method is used for products containing flue-cured tobacco, also called Virginia or bright tobacco. |
Each year, Altria’s tobacco companies purchase a mix of tobaccos cured using these varying methods. Of the total tobacco purchased in 2009, for example:
- sun- and air-cured accounted for 55 to 60 percent;
- flue-cured accounted for 30 to 35 percent; and
- fire-cured accounted for 10 to 15 percent.
Fuels used in Curing
Around the world, growers use a variety of energy sources to flue-cure tobacco. In the U.S., most indirect heating systems use propane or natural gas. A heat exchanger is mounted outside the curing barn and prevents the combustion gases from mixing with the heated air.
Growers in many countries now flue cure their tobacco in bulk in barns constructed out of metal that provides better insulation, more precise atmospheric control within the barn and more efficient use of energy. A fully-modified barn is likely to use less than 50 percent of the fuel used in an unmodified barn.
In some countries, wood is used as the fuel source for curing. In 2009, less than five percent of the total tobacco purchased by Philip Morris USA is cured using wood.
In Brazil, a country where wood is used to cure tobacco, one of PM USA’s leaf suppliers is working to reduce the impact of flue-cured tobacco production on trees.
In the U.S., sawdust and slabs that are by-products of the milled lumber industry, typically are used as the fuel for dark-fired tobacco. U.S. Smokeless Tobacco Co., purchases primarily American-grown, dark-fired tobacco.
Curing barn construction
Wood is often used in the construction of tobacco barns. According to a 2008 survey completed by the Center for Tobacco Grower Research, almost 50 percent of air-cured tobacco barns in the U.S. are more than 30 years old.
Outside the U.S., the lifespan of tobacco barns typically is shorter. For example, in Malawi, where PM USA and Middleton procure tobacco, the average barn lifespan is three years.
Learn how PM USA and Middleton are working to reduce the impact of air-cured tobacco production on trees in Malawi.
