Experts from the American Chemical Society have pointed out that hot coffee contains more antioxidants than cold extracted coffee.

Cold-extracted coffee is one of the most popular coffee drinks in recent years, but most people do not know enough about cold-extracted coffee. Recently, scientists have found that coffee extracted by hot and cold methods contains very different antioxidant health ingredients.

Recently, researchers involved in the study shared the results on the SciMetting platform of the American Chemical Society (ACS).

"this study can help coffee lovers learn how to make coffee at home through scientific and chemical analysis." Said Meghan Grim, a member of the research team.

"when I first tried to make cold coffee at home, I failed." Dr. Niny Z. Rao, one of the leaders of the research team, said. She and her colleague, Dr. Megan Fuller, flipped through the literature to try to find out the reason for the failure. "as it turns out, there was no research on cold-extracted coffee at that time." "so we're going to do our own research," Rao said.

In the process of making cold-extracted coffee, the coffee powder is mixed with water or cold water at room temperature for up to 2 days, sometimes soaked in the refrigerator, and can be used for cold or hot drinks. In the traditional hot coffee making process, the coffee powder is mixed with boiling or near-boiling water for a few minutes. In both cases, coffee powder sometimes needs to be pressed, and then the coffee grounds are filtered.

The team from Thomas Jefferson University tested the content of acids and antioxidants in lightly roasted coffee made by hot and cold extraction. In another study, they analyzed the effects of moderate and deep baking, as well as the effects of medium and rough grinding. Now they went further, roasting Colombian coffee at five temperatures, ranging from light roasting of 174 ℃ to deep roasting of 209 ℃, and studied the contents of acids, antioxidants and other natural ingredients in coffee made by hot and cold extraction.

When it comes to light roasted coffee, Rao's team found little difference in caffeine and antioxidants between hot and cold extracted coffee, but there was a big difference in deep roasted coffee. "Hot brewing coffee will extract more antioxidants, and the gap increases with the degree of roasting. "said Rao. Therefore, deep-roasted coffee extracted by hot water may have better health effects. Hot water extracted coffee also contains more specific types of acids and a higher total amount of soluble substances. The pH value of hot and cold extracted coffee had little difference among the coffee with the same roasting degree, and the acidity of the two kinds of coffee decreased with the increase of roasting temperature.