There are thousands of different chemical compounds in coffee and the scientists have not even researches about all of them. Some of the most prominent components in coffee are:
Carbohydrates represent almost 20-30 % in solid coffee. These carbohydrates cause the aroma in roasted coffee.
Nitrogenous compounds: These include proteins, trigonelline, alkaloids and amino acids. The most prominent one of the alkaloids is caffeine.
Vitamins and Minerals: Coffee includes vitamins like B1, B2, Pantothenic Acid, Vitamin B12, vitamin C, Nicotinic acid and Folic acid. The important minerals include Calcium, Sodium, phosphorus, Potassium, Iron, Zinc, Selenium and Manganese.
Volatile Compounds: There are hundreds of other compounds that are found in coffee and most of these are responsible for the distinctive aroma and unique flavor of coffee.
