CHAPTER 32: Polycyclic Aromatic Hydrocarbons

Roasting is a crucial step for the production of coffee leading to desirable aroma and colour. However, incidental compounds such as polycyclic aromatic hydrocarbons (PAHs) are also formed. Different roasting times and temperatures as well as the types of roaster and the cultivar entail different PAHs content, thus high variability in the PAHs levels can be found in the literature. The most abundant PAHs in roasted coffees are phenanthrene, fluoranthene, and pyrene with concentrations in some cases exceeding 100 µg kg⁻¹. These compounds present lower risk than those considered by the European Food Safety Agency (EFSA) as the possible indicators of the carcinogenic potency of PAHs in food, named as PAH8. However, significant concentrations of the carcinogenic benz(a)anthracene and chrysene have also been found, especially in coffees with higher roasted degree. Due to the low solubility in water, the extractability of compounds from coffee powder to the brew is low (less than 35%). Coffee brews show similar profiles when compared with ground coffee, phenanthrene, fluoranthene, and pyrene being the main PAHs. Additionally, with increasing roasting degree, a slightly lower extractability seems to occur. In general the content of PAHs in coffee brew indicates that coffee does not significantly contribute to the daily human intake of such carcinogenics.