Hydroxymethylfurfural and furfural in coffee and related beverages. III. Coffee related beverages

The contents of hydroxymethylfurfural (HMF) and furfural were determined in series of chicory roots, barley malt, barley, rye, figs and chickpeas with different degrees of roast. The contents first increase with increasing roasting loss (ORL), then decrease, the maxima being located near 3.5-6 % ORL (chickpeas, rye), 12 %(chicory), 17 % (figs) or higher. The contents increase in the order chickpeas, barley, rye, malt, figs, chicory, those of HMF always being much higher than those of furfural. In 14 commercial products (pure roasts and blends) corresponding levels were found. Two samples of roasted acorns contained levels similar to the barley ones. Storage of roasted chicory resulted in losses of HMF and furfural only at room temperature and presence of air, not at -18°C and not after evacuation. During heating with water, both substances are newly formed, but in open vessels furfural evaporates. The contents of5 instant products could be roughly explained by assuming a 100 % extraction rate of the two substances.