Is cold-extracted coffee healthier than hot coffee? what is the comparison between cold-extracted coffee and hot coffee?

Professional coffee knowledge exchange more coffee bean information please follow the coffee workshop (Wechat official account cafe_style)

In recent years, cold coffee has become more and more popular. From 2011 to 2016, the market for cold extracted coffee expanded by 580%. However, according to the Daily Mail of November 1, Dr. Niny Rao and Dr. Megan Fuller, chemical researchers at the University of Philadelphia and Thomas Jefferson University in the United States, published in the Science report (Scientific Reports) on October 30th, said: compared with hot coffee, the pH value of cold-extracted coffee has no significant change; and due to different coffee-making methods, hot coffee contains more antioxidants and is more beneficial to health.

Dr Niny Rao and Dr Megan Fuller are not only researchers of hot and cold coffee, but also lovers of both. They note that there are more and more claims about proving the health of cold extract coffee. Among them, the most common theory is that cold-extracted coffee has low acidity, so it can reduce the risk of gastrointestinal problems such as acid reflux and heartburn.

According to its research results, the pH values of hot coffee and cold extracted coffee are between 4.85 and 5.13, so different production methods have no significant effect on the PH value of coffee. In addition, they found that the total titration acidity and antioxidant activity of hot coffee were higher than those of cold-extracted coffee, which may be the reason for the higher antioxidant level of hot coffee.

Dr Megan Fuller said: "Coffee is rich in antioxidants. Studies have shown that drinking coffee in moderation is good for your health. We found that hot coffee has stronger antioxidant capacity. "

The emergence of cold coffee is to improve the flavor, not to solve health problems.

The process of "brewing" coffee is the process of extracting soluble substances from coffee powder into water. The purpose of grinding coffee beans into powder is to reduce the particle size and increase the contact area between water and coffee powder, thus speeding up the extraction process.

There are two key factors in the extraction process. One is "how much can be extracted into water". Professionally, it is a thermodynamic concept, indicating the maximum amount that can be extracted, and the other is "how fast is the extraction speed." professionally, it is a kinetic concept, indicating how much it can be extracted within a given period of time. In practical operation, the time used for extraction is always fixed, so the extraction speed is also very important.

The flavor of coffee is made up of extracted substances. There are at least hundreds of flavor substances in coffee beans, each of which has different thermodynamic and kinetic characteristics of extraction. Temperature, the ratio of coffee powder to water and extraction time determine the amount of these substances extracted into water.

Most importantly, different substances react differently to these conditions. Some substances are extracted more under this condition, and some substances are extracted more under that condition, so the same coffee will get different flavor if different extraction conditions are used.

Temperature has a great influence on the thermodynamics and kinetics of extraction. At low temperature, the extraction speed of all kinds of substances will be greatly reduced, but the extent of reduction of different substances is different. The idea of cold-extracted coffee is that at low temperatures, the extraction rate of astringent substances decreases more, and the content in the final coffee is relatively low, so the flavor of the coffee is better. Of course, because the extraction speed of all substances has slowed down greatly, so the cold extraction takes more than ten hours to complete.

There are no obvious "unhealthy" ingredients in coffee, so cold coffee or hot coffee, it doesn't matter which is "healthier". Of course, if the hot coffee temperature is too high (for example, higher than 65 °C), it will be unhealthy. However, this "disadvantage" is only the effect of high temperature and has nothing to do with coffee.