Particle size and variety of coffee used as variables in mitigation of furan and 2-methylfuran content in espresso coffee.

In this study, the concentration of furan and 2-methylfuran in espresso coffee (EC) obtained from Arabica and Robusta coffee varieties was determined as a function of specific particle size. The particle size and coffee variety significantly influenced the level of furan and 2-methylfuran. In Arabica variety, furan and 2-methylfuran level increased with increasing particle size. Particularly, from C<200µm to C>425µm fractions, furan increased from 68.27 to 91.48 ng mL-1 while 2-methylfuran from 404.31 to 634.64 ng mL-1. In Robusta variety, the highest concentration of furan and 2-methylfuran occurred in ECs prepared using C300-425µm fraction showing values of 116.39 ng mL-1 and 845.14 ng mL-1, respectively, for furan and 2-methylfuran. On the basis of this experiment, it is possible to establish a mitigation strategy by manipulating the particle size and coffee variety in order to reduce the level of furan and 2-methylfuran in EC up to 11.4% and 18.8%, respectively.

Processing effects on acrylamide content in roasted coffee production.

Acrylamide is a toxic compound that develops during the roasting process of coffee beans. According to literature, the levels of acrylamide in coffee vary with the percentage of Robusta type in the mix and with the time-temperature parameters during the roasting process. Therefore, this study aimed to find the best roasting conditions in order to mitigate acrylamide formation. Two types of roasted coffee (Arabica and Robusta) were analyzed through GC-MS and two clean-up methods were compared. The best roasting conditions were optimized on an industrial scale and the median levels of acrylamide decreased from the range 170-484 µg kg-1 to 159-351 µg kg-1, after the optimization of roasting parameters. Therefore, the choice of the best conditions, according to the percentage of Robusta type in the finished product, could be an efficient mitigation strategy for acrylamide formation in coffee, maintaining the manufacturer's requirements of the finished product.

Espresso coffee design based on non-monotonic granulometric distribution of aromatic profile.

Coffee beverages may be obtained using several extraction methods, among which espresso coffee (EC) represents now a worldwide adopted system. Recent advances in coffee grinding equipment allow today to achieve a detailed control of granulometric distribution, and the grinding process is an essential step of coffee production cycle both for the aromatic profile composition and for the chemical properties of the beverage (Severini, 2015). The comminution process consists of the breaking down particles into smaller fragments; as well-known, its main objective is to increase the overall particle surface area exposed to water leading to a more efficient extraction of soluble substances (Illy, 2005a). Basically, the coffee brewing process includes two steps: a washing phase concerning the snapshot dissolution of free solubles at the particle surface followed by diffusion phase of solubles within the porous particles (Spiro 1992, Baggenstoss 2008). The variability in particle size distribution on the quality of EC has been studied by various authors. Severini et al. has tackled the influence of the grinding level on the aromatic profiles and chemical attributes (percolation time, caffeine content, pH and titratable acidity) as a consequence of changes in the microstructural properties of the coffee cake. Generally speaking such results would imply that the final effect in terms of aromatic compounds extraction follows a monotonic law respect to granulometric size. This result is true in an average sense but it cannot be given for granted for any aromatic compounds if we refine the resolution of granulometric class. The reasons for which some aromatic compounds do not follow the supposed trend (the lower the grain size, the higher the aromatic compound content) can be most probably related to the internal distribution of precursors and to the different non-isotropic roasting grade of the bean, where the external part undergoes to an increased thermal load. This will change at the same time the kinetics and formation of aromatic compounds, and the mechanical properties as well, strictly correlated to the way the bean is crashed during the grinding phase and consequently to the granulometric distribution of different parts of the coffee bean. Results presented in this work allow to correlate choices in terms of granulometric distribution to characteristics aromatic compounds, in order to enhance specific flavors in espresso coffee.