Study on acrylamide formation and antioxidant activity in coffee during roasting

Acrylamide (AA) is a compound "potentially carcinogenic to humans" because its neurotoxic and genotoxic effects have been extensively highlighted. According to the new EU Regulation (2017/2158), new “mitigation measures and benchmark levels for the reduction of acrylamide in foods” have been established. AA is formed during thermal processes at temperatures greater than 120°C during Maillard reaction, a complex group of chemical reactions between the amino group of amino acids (mainly free asparagine) and the carbonyl group of reducing sugars (glucose and fructose). Coffee is one of foods with the highest AA level risk, because the raw material contains the reaction substrates and it is processed at very high temperature during roasting. On the other hand, it is well known that during roasting, of coffee a lot of beneficial antioxidants compounds are also formed. For these reasons, it is very important to evaluate the risks/benefits induced by this thermal process in coffee. In this study, Arabica and Robusta coffee samples were roasted in a lab-scale professional roaster for different times in order to obtain different roasting degrees (light, light-medium, medium, medium-dark, dark) with the aim of studying the evolution of AA level and antioxidant activity in both coffee species. Coffee samples were also analysed for the main physicochemical modifications induced by roasting (weight loss; density; moisture content; water activity; colour). The AA content was determined by HPLC-MS/MS triple quadrupole and the antioxidant activity were evaluated by Folin-Ciocalteu, FRAP, DPPH and ABTS assays. Obtained results showed that, after a progressive increase, AA level decreased when dark roasting level was reached. Antioxidant activity followed a similar behaviour.