Acoffee bean is a seed of the coffee plant, and isthe source for coffee. It is the pit inside the red or purple fruit oftenreferred to as a cherry. Even though they are seeds, they are incorrectlyreferred to as 'beans' because of their resemblance to true beans. The fruits -coffee cherries or coffee berries - most commonly contain two stones with theirflat sides together. A small percentage of cherries contain a single seed,instead of the usual two. This is called a peaberry. Like Brazil nuts (a seed)and white rice, coffee seeds consist mostly of endosperm.

 "Green coffee seed" refers to unroasted matureor immature coffee seeds. These have been processed by wet or dry methods forremoving the outer pulp and mucilage, and have an intact wax layer on the outersurface. When immature, they are green. When mature, they have a brown toyellow or reddish color, and typically weigh 300 to 330 mg per dried coffeeseed. Nonvolatile and volatile compounds in green coffee seeds, such ascaffeine, deter many insects and animals from eating them. Further, bothnonvolatile and volatile compounds contribute to the flavor of the coffee seedwhen it is roasted. Nonvolatile nitrogenous compounds (including alkaloids,trigonelline, proteins and free amino acids) and carbohydrates are of majorimportance in producing the full aroma of roasted coffee, and for itsbiological action. Since the mid 2000s green coffee extract has been sold as anutritional supplement, and has been clinically studied for its chlorogenicacid content and for its lipolytic and weight-loss properties.