The characterization of headspace volatile profiles of coffee under
two different processing temperatures was successfully carried
out by multivariate statistical analysis of the respective SPME/GC–
MS chromatograms. The analysis allowed for the discrimination between
crude and roasted samples, and between samples roasted to
varying degrees under different temperatures, regardless of compound
identification. The behavior of the discriminating compounds
was correlated to the weight loss curves during roasting,
which in turn presented distinct behavior for different roasting
temperatures. Caffeine, although not volatile, was encountered in
all headspace profiles and was one of the discriminating compounds
for crude coffee. Pyridine was the main discriminating compound
for coffees roasted at high temperatures and more intense
degrees of roast. Although discrimination of coffee samples roasted
to varying degrees was achieved by analyzing the effect of hundreds
of compounds altogether, the compounds that presented the most
pronounced effect on the discrimination of roasting degrees and
temperatures were those generated right after the onset of pyrolysis.
The results presented in this study show that color and weight
loss alone are not reliable as roasting degree assessment criteria
and that roasting temperature must also be taken into account.