Задание №15 — Чтение

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Coffee decaffeination processes

Every day it seems that medical researchers come out with a new study about coffee, how it is extremely unhealthy for you and/or full of amazing benefits. The focus of most of these studies is more particularly about the effects of caffeine on human health. As caffeine, coffee’s most potent element, is a stimulant, it can produce both positive and negative effects. It can wake you up in the morning, but it can also lead to sleeplessness, a racing heartbeat, and anxiety.

It is therefore no surprise that many people have decided to cut caffeine out of their diets. As for me, I have grown to like the taste of coffee, but to me the main purpose of drinking it is to get an extra jolt of energy. That is why I will admit to a certain prejudice against decaf, perhaps prompted by bad experiences with weak and tasteless brew, because it is true that the actual process of removing caffeine from coffee can degrade the taste beyond repair.

Early decaffeination attempts involved soaking the green beans in water and then using various solvents to separate the caffeine in the resulting water solution. The beans were then re-introduced to the caffeine-free solution in order to absorb some of the flavor they had lost. Solvents used included benzene, chloroform, and trichloroethylene, all of which were later found to have toxic effects. In the 1970s, dichloromethane came into use to replace the earlier solvents before it too was deemed possibly carcinogenic.

In response to these concerns about solvents, some coffee companies began to run the water solution through charcoal filters as a means of removing the caffeine. The so-called Swiss Water Process, developed in Switzerland in the 1930s, goes one step further. After a batch of coffee beans has been steeped in hot water, that water is filtered, and then is used to soak the next batch of beans to be processed. In this way, the beans lose caffeine as they soak, but lose less of their flavor.

Yet another method that aims to safely remove caffeine from coffee beans involves a fascinating compound procedure. The solvent used in this method is neither water nor one of the earlier toxic solvents. Instead, caffeine in the coffee beans is dissolved by means of carbon dioxide. In order to accomplish this, the carbon dioxide must become a supercritical fluid, created when it is compressed and heated to the point that it has the same density in liquid and gaseous forms.

As this supercritical CO₂ is passed through the beans, it can penetrate them because of its gaseous properties, and yet is able to dissolve the caffeine they contain because of its liquid properties.

In 2004, Brazilian scientists identified a new strain of coffee beans with a naturally low level of caffeine. They found three coffee plants from Ethiopia that contain almost no caffeine as they seem lack an enzyme necessary to caffeine production. If these plants can be crossed with commercial strains of coffee plants, we may one day see more coffee on the market that is naturally low in caffeine.

With these advances, and the current methods of decaffeination, decaf junkies are sure to be able to get their fix of coffee that not only tastes great, but won’t keep them up half the night.

As for me, I do want to stay up half the night, so I’ll stick to my full-strength brew.