Super trendy cold-brew coffee, which is made by steeping coffee grounds in cold or room-temperature water for up to 48 hours, is popular not only because it's got massive kick of caffeine, but also because it's believed to be less acidic option than the more traditional hot-brew. This made the drink a potentially good alternative for those of us who love java, but struggle with digestive issues, heartburn, or acid reflux. Turns out, that claim may not be true. A new study found that while there are differences between hot-brewed and cold-brewed coffee in their antioxidant levels, the low-acid claims of cold brew coffee might be overstated.
Related: Make cold brew coffee at home
Acidity of Cold Brew vs. Hot Brew
The idea that cold brew is low-acid can be pinpointed with reasonable certainty to a man in Colorado named Todd “Toddy” Simpson. Most references on the web to the low acid content of cold brew coffee either reference Simpson directly or use his figures, as seen on his website. Simpson, who sells cold brew equipment and coffee, stated as far back as 2009 that he conducted a study in which cold brew coffee tested as “67 percent less acidic” than hot coffee.
This new study was conducted by Megan Fuller and Niny Rao, researchers at Jefferson University. They tested six different coffee beans sourced from around the world, and measured their acidity levels after being brewed using the same bean-to-water ratio. The results? The pH values of the cold- and hot-brew samples ranged from 4.85 to 5.13, which means they're statistically similar—certainly nowhere near Simpson's mark of a 67-percent difference. In fact, some hot coffees were slightly more acidic than their cold-brew counterparts, some were less acidic, and some were almost identical. Amateur tests have indicated the same thing.
Antioxidants in Cold Brew vs. Hot Brew
That’s not to say that there's no difference in these two coffees, period. The researchers concluded that hot-brew coffee had higher antioxidant activity than their cold-brew counterparts, thanks to higher concentrations of what's called non-deprotonated acids. The total acidity—which is reflected in the flavor and impact on your esophagus—is pretty much the same, but there are lots of different types of acids, and cold and hot brew have different amounts of those. The non-deprotonated acids may be responsible for the higher antioxidant activity in hot coffee, but that doesn't necessarily make cold-brew coffee healthier.
In short, think again before ordering a cold-brew thinking it'll be more a little more pleasant on your stomach. Your best bet may to avoid a cup of Joe altogether.