Can I drink it right away? Why it's said to be better to let it sit a little after roasting.

I was once asked this question at my shop...

"I heard that it's better to let coffee sit for a while after roasting before drinking it, is that true?" Many people probably have questions about this idea of "letting coffee sit for a while after roasting," as it goes against the common belief that fresh equals good. While it might seem that, like fruits and vegetables, coffee is best when fresh, in the world of coffee, there's a school of thought that coffee beans are better after being left for a night or two after roasting. A key factor in this idea is "gas," which often comes up when discussing coffee freshness. This time, I'll explain the gas released from coffee beans that causes this phenomenon, and why coffee that has been left for a while after roasting is said to be better!

What is this gas?

Coffee lovers have probably seen airtight bags storing beans bulge, or noticed the coffee bloom into a dome-like froth when brewing. These are all caused by gas being released from the beans! The identity of this gas is carbon dioxide trapped inside roasted beans, meaning it's carbonic acid gas that's being released. In fact, this gas isn't present in green beans; it only starts to generate after a chemical change occurs within the beans during the roasting process. This gas serves as one indicator of coffee freshness. The gas slowly releases into the air over time, and as it does, the aroma is also released. Therefore, coffee that has lost a lot of gas has also lost a corresponding amount of aroma. Stale coffee, which has lost its freshness over time, might not bubble much or bloom beautifully when brewed, and this is because most of the gas has been released over time. In short, a high gas content is a sign of fresh and aromatic coffee!

Reasons why it's said to be better to let coffee sit after roasting

In the coffee industry, there's an idea that "it's better to let coffee beans sit for a while after roasting to allow the flavor to settle." There are several reasons for this, one of which is that "the release of gas hinders extraction." Beans immediately after roasting contain a large amount of gas, so if you grind and use them right away, large bubbles will appear the moment you pour hot water. This in itself isn't a bad thing; it's a natural phenomenon due to freshness. However, the problem is that the gas inhibits contact between the hot water and the beans. Coffee extraction is the process of allowing the components of the beans to come into contact with hot water and dissolve. When bubbles intervene, it becomes difficult for the hot water to touch the beans, making it impossible to dissolve the components, which tends to result in a slightly weaker coffee. The idea that "it's better to let coffee sit for a while after roasting" is based on the premise that when the gas no longer obstructs extraction after a short period, the extraction becomes stable and the coffee becomes more balanced. Hearing this might make it sound as if letting coffee sit after roasting is always necessary, but it's by no means forbidden to drink coffee immediately after roasting. There are flavors that can only be experienced right after roasting, and it's possible to achieve a robust flavor depending on how you brew it. While enjoying a settled flavor is certainly one way to enjoy coffee, there's no single "right" way to enjoy it. I think it's also wonderful to enjoy the change in coffee's flavor by drinking it daily from right after roasting!