The process is usually performed on unroasted (green) beans, and starts with the  steaming or soaking of the beans. They are then rinsed with a solvent that extracts the caffeine while leaving the other essential chemicals in the coffee beans. Coffee contains over 400 chemicals important to the taste and aroma of the final drink: It is, therefore, challenging to remove only caffeine while leaving the other chemicals at their original concentrations. Most major producers use one of the following decaffeination techniques.

The Direct Method: The coffee beans are first steamed for 30 minutes and then repeatedly rinsed with either dichloromethane or ethyl acetate for about 10 hours. The solvent is then drained away and the beans steamed for an additional 10 hours to remove residual solvent. Sometimes coffees that are decaffeinated using ethyl acetate are referred to as naturally processed because ethyl acetate can be derived from various fruits or vegetables, but because of the impracticality of gathering natural ethyl acetate, the ethyl acetate used for decaffeination is synthetic.

The Indirect Method: The beans are first soaked in hot water for several hours, in essence making a strong pot of coffee. Then the beans are removed and either dichloromethane or ethyl acetate is used to extract the caffeine from the water. As in other methods, the caffeine can then be separated from the organic solvent by simple evaporation. The same water is recycled through this two-step process with new batches of beans. An equilibrium is reached after several cycles, wherein the water and the beans have a similar composition except for the caffeine. After this point, the caffeine is the only material removed from the beans, so no coffee strength or other flavorings are lost. Because water is used in the initial phase of this process, sometimes indirect method decaffeination is referred to as “water-processed” even though chemicals are used.

Supercritical Fluid Extraction: Pre-steamed beans are immersed in supercritical carbon dioxide in a pressure chamber at 73 to 300 atmospheres. After a thorough soaking for around ten hours, the pressurized CO₂ containing dissolved caffeine is removed from the chamber which is returned to atmospheric pressure, allowing the CO₂ to evaporate. The caffeine is removed from the CO₂ using charcoal filters and is recycled for use on another batch of beans. This fluid works better than water because it is kept in a supercritical state, which displays lower diffusivity than gasses and smaller density than liquids. This process has the advantage that it avoids the use of potentially harmful substances.

Its important to keep in mind that not all beans are created equal, for example coffea arabica normally contains about half the caffeine of coffea robusta. In recent years their has been progress toward growing coffee beans that do not contain any caffeine at all. The naturally caffeine-free Coffea charrieriana has a deficient caffeine synthase gene, leading it to accumulate theobromine instead of converting it to caffeine. Either this trait could be bred into other coffee plants by crossing them with C. charrieriana or an equivalent effect could be achieved by knocking out the gene for caffeine synthase in normal coffee plants.

The toxicity of poisons, toxins and venoms is measured by the median lethal dose of the substance needed to kill 50 per cent of those exposed to it. It’s known as the LD50, as in lethal dose, 50 per cent. The LD50 statistic is usually expressed in measures such as the number of grams of the poisonous substance per kilogram of a person’ s body weight.

Every substance is toxic if ingested in large enough quantities. For instance, water has an LD50 of 90. This means that, if a large number of people each weighing 100 kilos (220 pounds) each drank 9,000 grams (20 pounds) of water at one sitting, it would kill half of them.  Table Sugar has a LD50 of 29.7, Grain Alcohol is 7.06, Table salt is 3.0, THC is 1.2, caffeine is 0.19, nicotine is 0.05, cyanide is 0.0064 and strychnine is 0.001.

At the extreme-toxicity end of the scale, botulinum toxin has an LD50 estimated at about 0.000000001, or one-billionth of a gram per kilogram. This is the lowest LD50 generally recorded for any substance.  Botulinum toxin is a neurotoxin produced by the bacterium Clostridium botulinum that can cause the severe food poisoning known as botulism.

Only a portion of the tobacco inside a cigarette comes from the leaf of a tobacco plant.

A significant amount of the shredded brown innards of most modern cigarettes is a paper product called “reconstituted tobacco” or “homogenized sheet tobacco,” which is made from a pulp of mashed tobacco stems and other parts of the tobacco leaf that would otherwise go to waste.

Manufacturers spray and impregnate reconstituted tobacco paper with nicotine and other substances lost during the process, along with as many as 600 chemical additives. These include several that may come as a surprise, such as ammonia, which aids in the delivery of nicotine, and chocolate, which masks the bitter taste of tobacco. Finally, the ‘recon’ is sliced to resemble shredded leaf tobacco. 

In addition to reconstituted tobacco, cigarette companies pack cigarettes with so-called puffed tobacco (also called “expanded tobacco”), which allows them to produce more cigarettes per pound of tobacco grown with lower levels of tar particles in the smoke. Manufacturers saturate this tobacco, which they make from the leaf of the plant, with freon and ammonia gases and then freeze-dry it. This process expands the tobacco, increasing its volume to at least double its natural state.

Though seemingly innocuous, cigarette paper is largely responsible for the rate at which a cigarette burns and the amount and density of the smoke it produces. The paper displays a pattern of concentric circle striations called “burn rings.” The burn rings correspond to two different thicknesses in the paper, which serve to precisely control the speed at which the cigarette burns, slowing it automatically when the smoker is not inhaling in order to prolong the cigarette’s consumption and speeding it up as the smoker takes a drag so as to maximize smoke intake. In addition, like the tobacco, the cigarette paper contains a host of chemicals, among them titanium oxide, which accelerates and maintains burning so the cigarette does not go out and the smoke is delivered evenly with each puff.

Credit Aaron St. John