How Much Black Coffee Is Appropriate to Drink Daily - What Is the Caffeine Content in a Cup of Coffee?

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Caffeine is something that people both love and hate. In the past, people have always consumed coffee cherries and coffee beans to obtain caffeine for its stimulating and exhilarating effects. Modern health advocates often view caffeine as an "enemy." For those who love coffee while also paying attention to their health, discussing which coffee has lower caffeine content has always been a hot topic, including discussions about caffeine content between dark roast and light roast coffee.

Which has higher caffeine content: dark roast or light roast coffee beans?

Some people believe that dark roast coffee beans contain more caffeine, meaning that as the roast level increases, the caffeine content also increases.

The reasoning behind this view is that the deeper the coffee bean is roasted, the lighter its weight becomes. If you need to weigh the same amount of coffee beans to brew coffee, then you'll need more dark roast coffee beans than light roast ones. Additionally, the structure of dark roast coffee is more porous, making it easier to extract substances. Therefore, it's believed that dark roast coffee has higher caffeine content than light roast coffee.

On the other hand, some argue that dark roast coffee beans have less caffeine because caffeine's melting point is 235-238°C. General coffee roasting rarely reaches such high temperatures, but caffeine begins to sublimate at 178°C, meaning the total caffeine content in coffee beans will decrease.

According to a report from the Association for Science and Information on Coffee, the caffeine content as a percentage of bean weight in light roast, medium roast, and dark roast Arabica coffee beans are 1.37%, 1.31%, and 1.31% respectively. That is, light roast has only 0.06% more caffeine.

Meanwhile, light roast coffee has a weight loss rate of 11-13%, while dark roast coffee has a weight loss rate of 15-17%. Therefore, dark roast coffee experiences minimal caffeine loss due to sublimation during the roasting process, but these losses are negligible. When consuming the same amount of coffee by weight, dark roast coffee will have higher caffeine content than light roast coffee beans due to weight loss and extraction efficiency.

Roast level is not the key factor affecting caffeine content

When it comes to caffeine content, we can look at it from two perspectives: the caffeine content in coffee beans and the caffeine content in brewed coffee.

The caffeine content in coffee beans is greatly related to coffee varieties and growing altitude. Arabica species contain about 0.9-1.4% caffeine, while Robusta species generally contain more than 2% caffeine, sometimes exceeding 3%. Different sub-varieties of Arabica coffee beans also have slightly different caffeine content in various regions.

Reference for caffeine content in major coffee-producing regions (Unit: %)

For the same coffee variety, the higher the growing altitude, the higher the caffeine content. This is because at higher altitudes, there's more sunlight and lower temperatures. Coffee plants receive sufficient nutrients while growing slowly, accumulating more substances. Therefore, caffeine content also increases.

However, people are more concerned about the caffeine content in brewed coffee, after all, not all caffeine contained in coffee beans is extracted into the coffee liquid. What we're really concerned about regarding caffeine intake is actually the amount of caffeine that dissolves in water.

The same coffee beans using different extraction methods will yield different caffeine content. If 15g of Arabica coffee beans are used for pour-over brewing, one cup of pour-over coffee contains about 100-150mg of caffeine (200ml of coffee liquid). Meanwhile, one shot of Arabica espresso contains about 50-100mg of caffeine (30ml of espresso liquid).

Overall, caffeine release is critically related to extraction time. The longer the contact time between water and coffee grounds, the more caffeine will be released. Therefore, for the same coffee beans with equal weight:

Cold brew coffee > French press > Pour-over coffee > Espresso

Is caffeine harmful to human health? How many cups of coffee can an adult drink per day?

In the past, there were always claims that children and pregnant women shouldn't drink coffee, stating that caffeine would affect the healthy growth of children and fetuses. Despite this, increasing evidence shows that moderate caffeine intake has significant benefits for human health.

Everyone's tolerance to caffeine varies. For normal adults, daily caffeine intake not exceeding 300mg (approximately two cups of pour-over coffee) can relieve fatigue and provide stimulating effects. Additionally, caffeine has some vasoconstrictive properties, which can also help improve tension headaches caused by fatigue.

However, people worry that caffeine is addictive and that excessive intake can harm the body. Unfortunately, caffeine's so-called "addiction" is not even as strong as your "addiction" to your phone. Caffeine is a stimulant to the central nervous system. Regular intake leads to mild physical dependence. If you suddenly stop intake, you may experience headaches, fatigue, anxiety, and inability to concentrate, but these symptoms will disappear within a few days of cessation and won't cause harm to your body. Only excessive intake will affect physical and mental health.

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