Changes in triacylglycerols and free fatty acids composition during storage of roasted coffee

Lipids are major coffee components, and changes in their composition during storage may contribute to loss of sensorial quality. In this study, changes in the triacylglycerols (TAG) and free fatty acids (FFA) composition of Coffea arabica seeds roasted to two color degrees (light medium and dark medium) were evaluated during storage for 6 months, under two temperature (5 °C and 25 °C) and atmosphere (air and N2) conditions. For the first time, hydrolysis of TAG fraction was observed during storage of roasted coffee, with increases in FFA, after 1 month storage, from 0.4 to 93.5 mg/100 g in light-medium samples and from non-detected to 1.1 mg/100 g in dark-medium samples. After 3 months storage, 20% and 13% decreases in FFA from light-medium and dark-medium samples, respectively, were observed, suggesting oxidation. The N2 atmosphere contributed to a slower loss of FFA. In the same way, at 5 °C, lower release of FFA was observed compared to 25 °C. Considering the inversion in the unsaturated FA (UFA) and saturated FA (SFA) contents observed in the dark-medium sample, the present results also show that the ratio Σ UFA/SFA, in TAG and AGL fractions might potentially be used as a tool to establish the shelf life of roasted coffee.

► For the first time, hydrolysis of TAG fraction was observed during storage of roasted coffee. ► The present results indicate oxidation of coffee free fatty acids during storage. ► Changes in coffee fatty acids are influenced by temperature and atmosphere when associated with storage time. ► The contents of triacylglicerols and free fatty acids in coffee are directly affected by the roasting process.