Tobacco and Public Health - TCSC Indonesia

70
THE CHANGING CIGARETTE: CHEMICAL STUDIES AND BIOASSAYS
blend has undergone gradual changes. In the 1960s and early 1970s, 45–50 per cent of
the cigarette blend comprised flue-cured (Virginia) tobaccos; 35 per cent, air-cured
(burley) tobaccos; and a few per cent were Maryland air-cured and oriental tobaccos.
By 1980, the average blend was composed of 38 per cent flue-cured, 33 per cent
air-cured, and a few per cent each of Maryland and oriental tobaccos. In the early
1990s, these proportions were about 35 per cent, 30 per cent, and, again, a few per cent
of Maryland and oriental tobaccos (Spears and Jones 1981; Hoffmann and Hoffmann
1997). The blended cigarette is preferred in many countries, in part because each of the
three major N. tabacum types adds a certain aroma to the smoke. Some isoprenoids,
and a relatively high number of agents with carboxyl content, are associated with the
aroma of flue-cured tobacco. Other isoprenoids, and especially the composition of the
acidic fraction, are related to the special aroma of air-cured tobaccos (Roberts and
Rowland 1962; Enzell 1976; Spears and Jones 1981; Tso 1990). 3-Methylbutanoic acid
(isovaleric acid) is considered to impart the most important flavor characteristic to
oriental tobacco (Stedman et al. 1963; Schumacher 1970).
However, in regard to the toxicity and carcinogenicity of tobacco and tobacco
smoke, the difference in the nitrate content of the tobaccos is of primary significance.
Flue-cured tobacco can contain up to 0.9 per cent of nitrate; yet, as it is used for regular
cigarettes, it contains