3rd meeting of young researchers at UP 1 - IJUP - Universidade do ...

Optimization of a HE-SPME-GC/MS method for screening of volatile
compounds in espresso coffee
C. Petisca 1 , A. Farah 2 , , O. Pinho 1,3 , IMPLVO. Ferreira 1
1 REQUIMTE- Department of Bromatology, Faculty of Pharmacy, University of Porto, Portugal.
2 Laboratory of Food and Nutritional Biochemistry, Department of Biochemistry – Chemistry Institute,
Federal University of Rio de Janeiro, RJ, Brazil.
3 Faculty of Nutrition and Food Sciences, University of Porto, Portugal
The consumer’s interest for espresso coffee has increased during the last few years not only in
Italy but also in other countries, namely, in Portugal and Spain. The espresso coffee is
appreciated due to its potent aroma, and flavour. These attributes are directly related to the
volatile compounds produced during roasting. The presence of defective coffee beans
depreciates the beverage quality. Considerable research dedicated to the volatile fraction of
roasted beans has been carried out. More than 800 volatile compounds are listed for coffee
when it is roasted. However, there are virtually no reports on the study of the headspace of
espresso coffee.[1,2]
The objective of the present study was to optimize a HE-SPME-GC/MS method for screening
of volatiles in espresso coffee and use it on the evaluation of the influence of roast conditions
of coffee beans with different percentages of defect (50, 60 and 73 % defective beans).
Twenty-five ml of espresso coffee samples were prepared directly to 50 ml vials. Extracts were
prepared from about 8 grams of coffee through which purified water of 88-95°C has been
forced at 9-10 atmospheres of pressure for a brew time of 20 seconds. The espresso dripped out
of the porta-filter like warm honey, have a deep reddish-brown color, and a crema that made up
10% of the beverage. Volatiles extraction and concentration was performed by solid phase
micro-extraction (SPME) of the espresso coffee headspace, using a carboxenpolydimethylsiloxane
(CAR-PDMS) fiber. Analysis of the volatile profiles was performed by
GC-MS.
The constituents were identified by comparing the experimental spectra with those of the US
National Institute of Standards and Technology (NIST) 1998 data bank 1.6, USA). Based on
the peak resolution, their areas were either calculated from the total ion current or estimated
from the integrations performed on selected ions. The results obtained showed that the
proposed methodology was reproducible and adequate for extraction, concentration and
analysis of espresso coffee volatiles. Statistical analysis of the data by principal components
(PCA) demonstrated that the volatile profile enables the differentiation of defective coffees.
References:
[1] Czerny, M.; Mayer, F.; Grosch, W. (1999), Sensory Study on the Character Impact Odorants of
Roasted Arabica Coffee, Journal of Agricultural and Food Chemistry, 47, 695-699.
[2] Illy, A.; Viani, R. (1995), Espresso Coffee: the Chemistry of Quality, in Illy, A., Viani R. (Eds);
Academic Press: London, U.K.
[3] Czerny, M. and Grosch, W. (2000), Potent Odorants of Raw Arabica Coffee. Their Changes during
Roasting, Journal of Agricultural and Food Chemistry, 48, 868-872.
96 3 rd meeting of young researchers at UP