Introduction of Coffee solvent extraction Swiss Water treatment Supercritical / liquid carbon dioxide High pressure extraction

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Are caffeine extraction techniques suspected of causing cancer?

At present, there are mainly three kinds of caffeine extraction techniques, and solvent extraction is widely used, but it also causes the most discussion, because the residual amount of organic solvents is always worrying.

1 solvent extraction method

● dichloromethane extraction method | does not affect the flavor of coffee, but the solvent is a possible carcinogen

Raw coffee beans are treated with high-pressure steam, adjust the water content of coffee beans, and then soak in dichloromethane solvent, so that beans fully contact with the solvent to extract caffeine.

Su Nan-Wei, a professor in the Department of Agricultural Chemistry and Department of biochemical Technology at National Taiwan University, said that this kind of extraction is the most cost-effective method, because dichloromethane has the highest extraction efficiency for caffeine, is easy to volatilize, is not easy to remain, and has low reactivity with other substances.

However, dichloromethane is suspected to be a carcinogen and is harmful to the environment, and dichloromethane is currently banned from food processing in Taiwan; however, this practice is approved by the US Food and Drug Administration (FDA), setting only the allowable residue limit.

Su Nanwei mentioned that if you import decaffeinated coffee beans, it is still possible to buy coffee beans extracted with dichloromethane. But he further explained that the boiling point of dichloromethane is so low that it can be volatilized when heated to about 30 ∼ and 40 ℃, and it is not easy to remain; caffeinated coffee beans also go through the baking step at a temperature of about 160 ∼ 230 ℃, which can make dichloromethane completely volatile. Therefore, although the National Cancer Institute (National Cancer Institute) considers dichloromethane as a possible carcinogen, FDA still permits it, setting the upper limit of allowable residues for decaffeinated beans or instant coffee as a caffeine extraction solvent at 10ppm. While most decaffeinated beans are only about 1ppm, or even less, the risk of cancer is actually not high.

● ethyl acetate extraction method | safe and common, but slightly affect the flavor

Ethyl acetate is a new substitute due to consumers' misgivings about dichloromethane. Ethyl acetate exists in nature, and even the content of ethyl acetate in some fruits is higher than that of low-caffeinated coffee, which is considered to be a safer choice and a common practice at present.

The boiling point of ethyl acetate is slightly higher than that of dichloromethane, about 77 ℃, which is also easy to volatilize. The disadvantage is that ethyl acetate will affect the properties of coffee beans, and the flavor of roasted coffee beans is poor.

2 Swiss Water treatment method (Swiss Water) | safer but more expensive

No matter it is dichloromethane or ethyl acetate, there are doubts about residual organic solvents, so the "washing method" is developed. Making use of the water solubility of caffeine, soak the coffee beans in warm water, after caffeine and other ingredients are dissolved in the water, adsorb the caffeine in the extract with activated carbon, and then introduce the non-caffeinated extract back to the previous coffee beans. let the coffee beans reabsorb the lost ingredients, and then dehydrate and dry the coffee beans.

This approach emphasizes the use of no organic solvents to extract caffeine, making it a choice for healthy eaters. But the disadvantage is that even allowing coffee beans to reabsorb non-caffeinated extract will still affect the flavor of coffee beans; not only that, the low-caffeinated coffee produced by this method is also more expensive.

(3) Supercritical / liquid carbon dioxide high pressure extraction | expensive

There are a variety of decaffeinated procedures using high-pressure carbon dioxide, which can be used not only to remove caffeine from raw coffee beans, but also to remove caffeine from roasted coffee beans.

The main principle is that under the condition of specific high pressure and temperature, carbon dioxide has good penetration properties, and the flavor or specific components of coffee beans can be extracted according to demand. coupled with pressure, temperature control and the water content of carbon dioxide used for extraction, caffeine in coffee beans can be effectively separated.

In this way, there is no problem of solvent residue at all, and the original coffee flavor can be added back to the coffee bean by multi-stage extraction technology to retain the original flavor of coffee bean. But the problem is that because of the need for special equipment, the price is very expensive and not popular.

In fact, whether it is regular coffee or decaffeinated coffee, "moderate drinking" and "less cream and sugar" are still the biggest principles. However, if you have high cholesterol or belong to a group with a high risk of cardiovascular disease, it is best to discuss with your doctor and dietitian whether you are suitable for decaffeinated coffee