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Kauai Coffee Roasting Guide

Roasting coffee transforms processed green beans into the fragrant and delicious Kauai Coffee you grind and brew every day. Get a behind the scenes look at the roasting process with this comprehensive coffee roasting guide and video tour of our roasting facility. 

Heat and the art of coffee roasting

Heat is the essential element of coffee roasting and what releases the array of flavors and aromas that make coffee so alluring. During the roasting process, high levels of heat are applied to green coffee beans, which causes a dramatic chemical change. Starting between 280 and 330 degrees Fahrenheit, the high temperatures inside the roaster force water and other volatile compounds out of the coffee beans. Then, sugars and amino groups in proteins react with the heat and cause the beans to brown. This reaction is called the Maillard reaction and is the same chemical process that creates the distinct and delicious flavors of browned foods like steak, pan-seared vegetables, and toasted marshmallows.

coffee roasting chart shutterstock: pongpinun traisrisilp

shutterstock: pongpinun traisrisilp

 As the temperature increases, further chemical reactions take place. Once the water inside the beans is completely vaporized around 400 degrees Fahrenheit, the beans expand and crack. A light roast coffee is done at this point, but medium and dark roast beans continue to react and change. Around 430 degrees Fahrenheit, coffee beans undergo a chemical process called Pyrolysis, which causes the release of carbon dioxide and a second crack, which gives the beans their deep, rich color and dark roast beans an oily sheen.

Timing is everything

Time is another critical element of coffee roasting and much more challenging to master. The difference between the desired roast level and a burned bean can be just a matter of seconds. That's why experience matters. At Kauai Coffee, we are lucky to have some of the best coffee roasters in the business. In fact, of the twelve licensed Q graders in the state of Hawaii, we are fortunate to have two – Roastmaster Mike Shimatsu and Quality Assurance technician Jorge DeLeon. Together they lead our exceptional roasting team and ensure perfectly roasted, island-grown coffee is delivered to you and your family every time.
kauai coffee roasting guide


Coffee roasting is an activity where all your senses are engaged. The color of the beans, sounds, and aromas they produce are all clues to achieving the perfect roast. Thankfully we also have technology. When beans enter the roaster, we can select the desired roast level with software, but it still takes a human touch to get it just right. At Kauai Coffee, our commercial roasting equipment can roast between 28 and 32 100 pound batches per day, an average of 63,000 pounds per month! Processed green beans enter the roasting plant via conveyor belt and are then added to the roaster one batch at a time.

Once the desired roast level and settings are selected, it’s time to roast! As the beans roast, they are closely monitored. A small scoop is inserted into the roasting drum every few seconds to check the beans. As soon as the desired roast is achieved, the beans are quickly transferred to a cooling drum, where they are gently stirred to reduce their temperature and stop the roasting process.

coffee roasting guide

Shutterstock: Jane Rix

Coffee Roast Types

Surprisingly, there is not much industry standardization when it comes to coffee roasting types and labels. Each roastmaster may have their own equipment, time, and temperature formulas for achieving their signature roasts. However, most specialty coffee roasts, including ours, fall somewhere on a spectrum of light to medium, medium-dark, and dark roasts.

Light roasts Light roast coffee is light brown in color and retains more caffeine than darker roasts. In general, it has a mild flavor and more acidity or brightness than darker roasts because the beans haven't roasted long enough to force the natural oils out of the bean. Another appealing quality of light roast coffee is that you may taste more flavor nuances unique to its origin. When purchasing light roast coffee, look for labels with the following descriptors:

  • Light roast
  • Light city roast
  • Half city roast
  • Cinnamon roast
kauai coffee poipu estate medium roast
Medium Roasts Medium roast coffee is sometimes referred to as American roast because of its popularity in the USA. Medium roast coffee is a deeper brown color than light roast but still retains a matte or unglossy finish. Medium roast coffee strikes a balance between bright, sweet, and bitter flavors, which is why it is a palate pleaser for so many. When shopping for medium roasts, look for labels such as:
  • Medium roast
  • City roast
  • Breakfast roast
  • American roast
At Kauai Coffee, our medium roast coffees include:
kauai coffee medium dark roast
Medium-Dark Roasts Coffee roasted to a medium-dark level is a rich, dark brown color and has a slightly oily or glossy finish. At this roast level, the natural oils in the coffee bean are forced to the surface, and most of the acidic bite or brightness you can taste in light and medium roast coffees all but disappears. Medium-dark roast coffee can have a sweet aftertaste that balances well with the more bitter flavor notes that can appear at this roast level. When shopping for medium roast coffee, look for labels that say:
  • Medium-dark
  • 50/50
  • Full city roast
At Kauai Coffee, our medium-dark roasts include:
blue mountain coffee
Dark roasts The darker the roast, the less caffeine the coffee will contain. Dark roast coffee is very dark in color with a gleaming, oily finish. The most notable flavor attribute of dark roast coffee is its striking bitterness. Because of the pronounced bitter notes of dark roast coffee, it pairs exceptionally well with milk or cream. Dark roast coffee is called by many names. When shopping for dark roast coffee, look for labels such as:
  • Dark roast
  • French roast
  • Italian roast
  • Espresso roast
  • Continental roast
At Kauai Coffee, our dark roasts include:
Wailani demonstrating coffee roasting at the visitor center

See the Coffee Roasting Process in Person

Want to learn more about the art of roasting coffee? Join us for a free coffee roasting demonstration at the Kauai Coffee Visitor Center. Roasting demonstrations occur Sunday through Thursday at 9:30 a.m. and most afternoons. Join us for a Farm Tour to see the entire process from seed to cup! Kauai Coffee farm tours are offered Monday through Friday from 9:00 a.m. to 11:00 a.m.
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