Most people pick a brewing method based on how it tastes, how easy it is, or what they’ve always done. It doesn’t come up very often at the counter that the method itself might affect how much of a compound that helps your brain ends up in the cup. But scientists who study coffee chemistry in depth have been asking that very question, and the answers are really interesting.
It is chlorogenic acid that is at the heart of this. As much as eight percent of the dry weight of Arabica beans and even more of the dry weight of Robusta beans are made up of this compound. It’s a strong antioxidant, which means it can fight free radicals and lower oxidative stress. Researchers have linked it to reducing inflammation, better control of blood sugar, and a lower risk of heart disease. Some studies have also found links between drinking a lot of chlorogenic acid-rich coffee on a regular basis and a lower risk of cognitive decline, such as dementia after a stroke. That’s the mental link that makes the question of extraction important to ask.
The main tension is that espresso is made quickly and intensely at nine bars of pressure in about thirty seconds. Cold brew is slow and gentle. It is made by letting coffee grounds steep in water at room temperature or in the fridge for six to twenty-four hours. They both end up in a cup. They don’t have the same things in the end, though. There are 30 to 140 milligrams of chlorogenic acid in an espresso cup, but this depends on the bean and the level of roasting. Cold brew coffee that has been brewed for twelve to twenty-four hours can have 150 to 300 milligrams of caffeine per cup. That is a big difference, and it has to do with heat.
Chlorogenic acid doesn’t like heat. Some of the compound is broken down before it even gets to the cup because of the high temperatures used in espresso extraction and even regular hot-brew methods. That breakdown doesn’t happen at all with cold extraction. The water moves more slowly, but it keeps the things inside safe. This is another reason why roast level is so important: darker roasts lose more chlorogenic acid during roasting. This means that no matter how well the cold brew is made, a dark-roasted cold brew starts with less of the compound to extract.
Things get trickier when high-pressure processing is used, which is a technology that is being used in cold extraction to make brewing much faster. Frontiers in Chemistry published a study in September 2025 that looked at a system called Hardtank technology. It was made by researchers at the University of Life Sciences in Lublin, Poland. The system changes the pressure between 0.3 and 1.5 bar so that cold extraction can happen in just 30 minutes. Instead of static steeping, water flows continuously through a coffee bed. The results were very interesting. The Hardtank process was 172% more effective at extracting chlorogenic acid than a 70% methanol reflux extraction that was used as a standard in the lab. This means that it got more of the compound out of the plant than the reference method. It made a drink called Nitro Cold Brew that had about 78 to 82 milligrams of chlorogenic acid per 100 milliliters. This is more than twice as much as is in a regular hot-water roasted coffee infusion.
That is something to pause on. The amount of chlorogenic acid in a cold-extraction method that was finished in thirty minutes was higher than that of both regular cold brew and regular espresso. It looks like the controlled low pressure, moving air flow, and lack of heat help pull more of the compound out of the ground without damaging what it finds. The system also kept caffeic acid and its derivatives, which couldn’t be found in any of the other brewing methods tested in the same study.
It’s still not clear if these benefits seen in the lab can be directly translated into better health or brain function for people drinking the coffee. Simply put, the study only looks at what’s in the cup and doesn’t say exactly what happens in the body after drinking it. Bioavailability is a different question. The way compounds like chlorogenic acid act after being eaten is affected by things like the microbiome in each person’s gut, differences in metabolism, and the person’s overall diet.
Seeing how this field of study grows makes me think that the conversation about coffee brewing methods is just now starting to catch up with what the chemistry has been saying for years. Picking between cold and hot extraction isn’t just a matter of taste or how you like to start your day. There is a choice about what goes into the drink, and science has more and more specific things to say about that.
