[Study of pyrolysates of beta-carotene in tobacco].

Relationships between tobacco compounds and smoke products are complex and often difficult to unravel. Pyrolysis experiments have frequently been used to establish such relationships. The relevance of pyrolysis experiments to the behavior of tobacco constituent in a burning cigarette was studied. A set of pyrolysis conditions has been developed to study the effect of thermal degradation of beta-carotene to the cigarette smoke quality, and the conditions was approximated to those occurring in the pyrolysis region of the burning cigarette. The pyrolysates of beta-carotene were investigated in air, 10% O2 (in N2) and N2 at three temperature levels of 300 degrees C, 600 degrees C and 900 degrees C, respectively. The pyrolysates were adsorbed by solid-phase microextraction (SPME) and then analyzed by gas chromatography/mass spectrometry (GC/ MS). Under the different conditions, the major pyrolysates from beta-carotene are hydrocarbon compounds such as toluene, p-xylene, 1, 2, 3, 4-tetrahydro-1, 1, 6-trimethyl-naphthalene and 2, 7-dimethyl-naphthalene, and some important flavors existing in cigarette smoke such as isophorone, 2, 6, 6-trimethyl-1-cyclohexene-1-carboxaldehyde, beta-ionone and 5, 6, 7, 7a-tetrahydro-4, 4, 7 a-trimethyl-2 (4H)-benzofuranone. The amount of these pyrolysates alters with the change of pyrolysis temperature levels and the concentration of oxygen.