By Dr. Jack Wolfson
Feb 11, 2021

Light, medium or dark roast. Which do you prefer?

Coffee starts out as a green seed. The seeds are dried prior to the roasting process.

Once in the roaster, the coffee absorbs heat and the color shifts to yellow and then to increasingly darker shades of brown. During the later stages of roasting, oils appear on the surface of the bean.

The roast will continue to darken until it is removed from the heat source. Coffee also darkens as it ages, making color alone a poor roast determinant. Most roasters use a combination of temperature, smell, color, and sound to monitor the roasting process.

Sound is a good indicator of temperature during roasting. There are two temperature thresholds called "cracks" that roasters listen for. At approximately 196 °C (385 °F), the coffee will emit a cracking sound. This point is referred to as "first crack," marking the beginnings of a "light roast". At first crack, a large amount of the coffee's moisture has evaporated, and the beans will increase in size. When the coffee reaches approximately 224 °C (435 °F), it emits a "second crack", this sound represents the structure of the coffee starting to collapse. Now it is a medium roast. If the roast is allowed to progress further, it begins to take on the characteristics of the roasting process and loses the characteristics of the coffee's origin. At this point, the coffee is considered a dark roast.

Each level of roasting has its own characteristics. The light roast retains the varied flavors of fruit due to high amounts of an organic compound, 5-hydroxymethylfurfural, while maintaining an acidic finish. A medium roast loses the acidity and takes on the roasted flavors of caramel and chocolate. A dark roast brings the oils to the surface of the bean with the distinct burnt flavor of coffee at high temperatures.

The darker the roast, the lower the caffeine content is a standard rule. But caffeinated coffee is full of caffeine no matter how you roast it.

Finally, a major component of the green coffee seed with tremendous health benefits is chlorogenic acid. The more we roast the bean, the more chlorogenic acid is lost.

For Cardiology Coffee, we chose a medium roast as a middle ground to preserve antioxidants and phytonutrients from the green seed while benefiting from the nutritional compounds created in the roasting process.

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