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 degrees C and 25 degrees C) and atmosphere (air and N-2) 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 N-2 atmosphere contributed to a slower loss of FFA. In the same way, at 5 degrees C, lower release of FFA was observed compared to 25 degrees 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 Sigma UFA/SFA, in TAG and AGL fractions might potentially be used as a tool to establish the shelf life of roasted coffee. (C) 2012 Elsevier Ltd. All rights reserved.