The science of coffee
A highly complex beverage
Coffee may appear to be a simple drink, but in reality it is a highly complex product. It is derived from over 1500 chemical substances (approximately 850 volatile and 700 soluble), and when prepared correctly involves 13 independent chemical and physical variables. Understandably then, the science of coffee is highly specialized, requiring a multidisciplinary approach involving the fields of genetics, agronomy, botany, physics, mathematics, chemistry, biochemistry, biology, engineering and physiology, among others.
The Raw Bean
Coffee science begins with the growing process, where many factors influence the overall quality and chemical composition of the raw coffee bean: the location, altitude and weather of the plantation, the composition of the soil and its fertilization, and finally the cultivation, harvesting and drying methods used.
Roasting Science
Most of the delightful aromatic character of coffee is the result of the roasting process. From the chemist’s point of view, the coffee beans undergo what is known as Maillard reaction browning—the process by which water and carbon dioxide are released and a reaction between sugars and amino acids results in the formation of the roasted color and flavor. The high temperature and elevated pressure inside the bean trigger a vast number of chemical reactions that alter or create volatile aroma compounds, acids and other critical flavor components. Learn more. The overall balance of these components is highly sensitive to the roasting time, temperature and technique—parameters which are under the control of the coffee roaster and which make coffee roasting something of an art as well as a science.
The first phase of roasting is where heat transfer begins to take place; in other words, the raw bean starts to absorb heat as it slowly dries and takes on a yellow color. As the process continues, a pleasant toasted smell begins to develop. In the second roasting phase, the bean puffs up, doubling in size and becoming a light tan color. Next, as the roasting temperature continues to rise, the color deepens and the bean loses weight and becomes more brittle, Its density decreases and CO2 is released, a process that continues for several days after roasting. At higher temperatures and longer roasting times, the volatile aroma compounds responsible for coffee flavor are actually destroyed, rather than created. The roast degree determines the final color and flavor of the bean and is largely a matter of personal preference.
Coffee Flavor
Some people may be surprised to learn that coffee aroma is responsible for all its flavor attributes, other than sweet, sour, bitter and salt tastes that are registered by the tongue. Aroma is sensed by smelling the coffee and also retro-nasally when volatile compounds waft into the nasal passages while coffee is in the mouth or has been swallowed. A mixture of approximately 25 highly potent volatile compounds of the over 850 identified so far—many concentrated in the coffee oil and present at concentrations in the part per million and part per trillion range—are responsible for most of the experience we know as coffee taste.
Caffeine
Caffeine is the most widely consumed pharmacologically active substance in the world, and is found naturally not only in coffee and tea, but in cocoa and chocolate products as well as over 60 other plant species. Chemically speaking, caffeine is a white crystalline substance that belongs to the alkaloid family of compounds and, like all alkaloids, has a bitter taste. It is absorbed directly from the gastrointestinal tract with peak blood levels occurring about 30 minutes after consumption.
The amount of caffeine in a cup of coffee varies widely depending on the type and amount of coffee used and the method of preparation, and can range from 40mg - 150mg. On average, Arabica beans contain about 1.1% caffeine while Robusta beans contain about twice that level.. Contrary to popular belief, a cup of espresso is lower in caffeine than a cup of brewed coffee due to the fact that there is less contact time between the coffee and water. A cup of illy espresso contains, on average, 78mg of caffeine while a cup of brewed illy averages 120mg.
Caffeine has a well-known mild stimulant effect and its consumption elevates neural activity in the brain. It can postpone fatigue and in many studies, has been shown to enhance cognitive performance and increase the body’s capacity for exercise and physical endurance. For further information: http://coffeescience.org/alert
Antioxidant Properties
Coffee has a very high antioxidant content and is, in fact, the greatest source of antioxidants in the U.S. diet according to University of Scranton professor Dr. Joe Vinson. Antioxidants have been widely linked to a number of potential health benefits including protection against heart disease and cancer.
other health benefits
Coffee’s effect on health has been widely studied, and while there have been many conflicting and contradictory reports over the years, the vast majority of recent scientific activity shows many very positive health benefits associated with drinking coffee. In addition to coffee’s well-known ability to increase performance on mental and physical tasks, coffee drinking has been strongly linked to lowering the risk of colorectal and liver cancers, asthma, type 2 diabetes, Alzheimer’s disease and Parkinson’s disease.
For further information visit Positively Coffee http://www.positivelycoffee.com/
This Positively Coffee website is part of the Positive Communication programme of the International Coffee Organization (ICO).