In the cigarette industry it is usual to expand tobacco and thus increase its filling ability. The tobacco is impregnated with a volatile medium (expansion medium) and subsequently warmed to expel the medium. The associated increase in the volume of the expansion medium causes the expansion of the tobacco.
Messer uses both nitrogen and carbon dioxide as tobacco expansion media.
Expansion medium nitrogen:
In high-pressure autoclaves, nitrogen is added to the fine-cut tobacco at around 800 bar with the pressure then being suddenly released. This process of rapidly releasing the pressure ensures an extreme cooling of the tobacco and prevents soaking of the nitrogen into the tobacco fibres. In the subsequent process, nitrogen is driven out using steam. This heat treatment causes a sudden expansion of the nitrogen and thereby an increase in the tobacco volume.
Expansion medium carbon dioxide:
Carbon dioxide at 30 bar is added to the tobacco so that it dissolves in the product. Through the subsequent expansion, solid CO2 builds up in the plant fibres. Heating shortly at up to 400°C ensures the sublimation of the CO2 and therefore expansion of the tobacco.
Expanding the tobacco can lead to doubling of the product volume.
- Cost savings
- Lower amounts of tar and nicotine for the consumer
- Smoke characteristics do not change with the addition of approx. 10% expanded tobacco