Antioxidants in Coffee
According to a number of studies, coffee is the single richest source of antioxidants in human diet. Most of us intake between one and two grams of antioxidants every day from certain vegetables, fruits, berries, vegetable oils, honey, tea, coffee, cocoa, juices, wine, sprouted grains, and other foods, but most of it comes from coffee. While some berries are found to be richer in antioxidants like polyphenols than coffee, the fact is that we do not eat enough berries to make them a significant source, while we drink three to four cups of coffee every day. In Norwegian and Finnish studies, coffee (two to four cups) was shown to provide about 64% of our total antioxidant intake.
It is important to note that coffee does not contain the same antioxidants as different fruits and vegetables. Since each antioxidant has a particular role in our system, it is important to have a balanced diet that includes a variety of fresh produce besides your favourite java.
Due to the rich content of compounds with antioxidant properties, the researchers found that coffee drinkers have almost 50percent lower risk of type 2 diabetes, a lower risk of liver cirrhosis, lower risk of liver and colorectal cancer and reduced risk of heart disease and stroke.
What antioxidants are found in coffee?
With more than 1000 active ingredients in coffee, we are still learning which ones have antioxidant properties. Coffee provides a high content of chlorogenic acids and caffeine, as well as a significant content of nicotinic acid, trigonelline, tocopherols, cafestol, kahweol, and heterocyclic compounds. Volatile compounds, such as furans, pyrroles, formed by pyrolysis of coffee, also show antioxidant activity.
Melanoidins (brown pigments) are synthesized by roasting coffee and are found to be strong antioxidants . In some publications, caffeine is also considered to be antioxidant. . Phenylalanines, also formed during the roasting process, show high antioxidant activity , as do heterocyclic compounds .
The antioxidant activity in coffee depends on many factors, including geography. Chlorogenic acid and polyphenols are found in larger concentration in Arabica coffee fruit from Mexico and India than coffee grown in China. Extraction procedure also affects the antioxidants contents in coffee fruit. The studies show that the antioxidant activity was higher in coffee with lower caffeine concentration compared to coffee fruit powder. The chemical composition of the raw green beans and post-harvest processing such as drying, storage, roasting, and grinding also affect the antioxidants. While phenolic antioxidants are degraded by the roasting process, the same process triggers the formation of other compounds with antioxidant activity, such as Maillard reaction products.