What determines the caffeine content in coffee beans? The key to this refreshing drink

Caffeine is an essential element in many people's daily lives, helping us stay alert and improve our concentration. For coffee lovers, understanding the factors that affect the caffeine content in coffee beans can help them better choose the coffee that suits them. What exactly determines the caffeine content in coffee beans?

Caffeine Basics

A standard 8-ounce cup of coffee contains 95–200 mg of caffeine, while a 1-ounce cup of espresso contains 47–75 mg. According to some studies, it is generally safe for healthy adults to consume no more than 400 mg of caffeine per day.

Research suggests that moderate caffeine consumption may offer a variety of health benefits, including a lower risk of Alzheimer's disease, certain cancers, stroke, and Parkinson's disease, and even a reduction in the risk of suicide (by up to 45%). On a more everyday level, studies have also shown that caffeine can improve concentration and memory.

The relationship between coffee roasting degree and caffeine content

Many people believe that darker roasted coffee contains more caffeine, but this is actually a misconception. Caffeine is very stable during the roasting process, and the degree of roasting of coffee beans does not significantly change the absolute caffeine content.

So why do people have this misunderstanding? The key is how you measure:

• Volume measurement : If you measure ground coffee with a spoon, lighter roasted coffee will have more caffeine. This is because lightly roasted coffee beans are denser and contain more coffee beans in the same volume.
• Weight Measurement : Dark roasted coffee may contain a higher percentage of caffeine if measured by weight. This is because more water is lost during the dark roasting process, which increases the proportion of caffeine in the total weight.

During roasting, the density of coffee beans changes: the longer they are roasted, the lower the density, mainly due to water loss. Interestingly, unroasted coffee beans sink in water, while roasted coffee beans float, mainly because the carbon dioxide produced during the roasting process becomes trapped inside the beans.

Effects of Altitude

The altitude at which coffee beans are grown has a significant effect on their caffeine content:

• At higher altitudes (above 900-1500 meters), where the air has lower oxygen levels, coffee trees grow and mature more slowly, which gives the beans longer to develop more complex flavors.
• High altitude coffee beans are usually denser, which is directly related to the quality of the coffee beans.
• Studies have shown that increasing from moderate altitude to high altitude (approximately 400 meters) can reduce caffeine content by about 10%.

The lower temperatures at higher altitudes cause coffee trees to grow more slowly, which prolongs the beans’ development time. This longer maturation process allows the beans to accumulate more complex sugars, producing a deeper, more engaging flavor. Additionally, higher altitudes provide better drainage, which reduces the amount of water in the fruit and further concentrates the flavor.

Effect of shade level

The amount of shade in the coffee tree's growing environment also affects the quality and caffeine content of the coffee beans:

• Limited sunlight exposure and high altitude have a significant positive effect on coffee bean density, making the beans harder and heavier.
• At higher altitudes, adequate shade (open or medium shade) combined with early to mid-season harvesting times can produce higher quality coffee beans.
• Excessive shade may reduce the quality of coffee beans. Studies have shown that at high altitudes, dense shading can reduce top-grade (Q1) coffee yields by 50%.

Differences between coffee tree species

The type of coffee plant is another important factor affecting caffeine content:

• Robusta coffee contains nearly twice as much caffeine as Arabica.
• Arabica coffee beans generally need to be grown at higher altitudes, where there are fewer pests.
• Robusta coffee can survive even at sea level due to its high caffeine content, which is toxic to most pests and acts as a natural pesticide.

The relationship between caffeine and bitterness

Although caffeine is a bitter compound, it actually only contributes about 15% of coffee's bitterness. Coffee contains more than 1,000 chemicals that together affect its taste and aroma.

According to research by Dr. Thomas Hofmann, professor of food chemistry and molecular sensory science at the Technical University of Munich in Germany, there are two main sources of bitterness in coffee: chlorogenic acid lactones and phenylindoles. Both of these substances are derived from chlorogenic acid, which itself is not bitter. Chlorogenic acid is found in unroasted green coffee beans.

Hofmann's research shows that roasting is a key factor affecting the bitterness of coffee beans. The darker the coffee is roasted, the more bitter it is. This discovery overturns people's understanding of the main source of coffee's bitterness.

Practical purchasing advice

Based on the above factors, if you want to adjust the caffeine content in your coffee, you can consider the following:

1. Go for high caffeine : Choose Robusta beans, light roasts, coffee produced at low to medium altitudes, and measure ground coffee by weight rather than volume.

2. Go for low caffeine : Choose Arabica coffee beans, coffee grown at high altitudes, and produced in a moderate shade environment.

3. Balance flavor and caffeine : Consider mixing different types of coffee beans, such as mixing a small amount of Robusta with high-quality Arabica to get the right amount of caffeine to stimulate the body while maintaining good flavor.

Learn these secrets of caffeine so that every cup of coffee can be a precise and pleasurable experience, injecting just the right amount of energy into your day.