The GC/MS identification of volatiles formed during the roasting of high molecular mass coffee aroma precursors

Volatile compounds formed during the roasting of green coffee fractions were analyzed by GC/MS. The green coffee aroma precursor fractions studied were: fraction 1, water-insoluble and rich in polysaccharides and proteins, and fraction 2, representing the total lipids from the green bean. A loss of 46% of arabinose was observed in fraction 1, indicating that arabinogalactan, present in this fraction, is more sensitive to roasting than other polysaccharides such as mannan and glucan. The results indicate that arabinogalactan is the main polysaccharide involved in the formation of furans in roasted coffee. Amino acids, particularly threonine, appear to be the source of pyrazine during coffee roasting. Lipids appear to contribute very little to aroma formation in roasted coffee.