Insights on Single-Dose Espresso Coffee Capsules' Volatile Profile: From Ground Powder Volatiles to Prediction of Espresso Brew Aroma Properties  
[PERSON]  
1 LAQV-REQUIMUTE, Chemistry Department, Campus Universitario de Santiago, University of Aveiro, 3810-193 Aveiro, Portugal; [EMAIL_ADDRESS] (G.R.L. ); [EMAIL_ADDRESS] (M.S.F. ); [EMAIL_ADDRESS] (M.P.P. ); [EMAIL_ADDRESS] (P.C.P. ); [EMAIL_ADDRESS] (E.C. ); [EMAIL_ADDRESS] (S.M.R. ); [EMAIL_ADDRESS] (M.A.C.) [PERSON]  
1 LAQV-REQUIMUTE, Chemistry Department, Campus Universitario de Santiago, University of Aveiro, 3810-193 Aveiro, Portugal; [EMAIL_ADDRESS] (G.R.L. ); [EMAIL_ADDRESS] (M.S.F. ); [EMAIL_ADDRESS] (M.P.P. ); [EMAIL_ADDRESS] (P.C.P. ); [EMAIL_ADDRESS] (E.C. ); [EMAIL_ADDRESS] (S.M.R. ); [EMAIL_ADDRESS] (M.A.C.) [PERSON]  
1 LAQV-REQUIMUTE, Chemistry Department, Campus Universitario de Santiago, University of Aveiro, 3810-193 Aveiro, Portugal; [EMAIL_ADDRESS] (G.R.L. ); [EMAIL_ADDRESS] (M.S.F. ); [EMAIL_ADDRESS] (M.P.P. ); [EMAIL_ADDRESS] (P.C.P. ); [EMAIL_ADDRESS] (E.C. ); [EMAIL_ADDRESS] (S.M.R. ); [EMAIL_ADDRESS] (M.A.C.) [PERSON]  
1 LAQV-REQUIMUTE, Chemistry Department, Campus Universitario de Santiago, University of Aveiro, 3810-193 Aveiro, Portugal; [EMAIL_ADDRESS] (G.R.L. ); [EMAIL_ADDRESS] (G.S.F. ); [EMAIL_ADDRESS] (M.P.P. ); [EMAIL_ADDRESS] (P.C.P. ); [EMAIL_ADDRESS] (E.C. ); [EMAIL_ADDRESS] (S.M.R. ); [EMAIL_ADDRESS] (M.A.C.) [PERSON]. [PERSON]  
1 LAQV-REQUIMUTE, Chemistry Department, Campus Universitario de Santiago, University of Aveiro, 3810-193 Aveiro, Portugal; [EMAIL_ADDRESS] (G.R.L. ); [EMAIL_ADDRESS] (M.S.F. ); [EMAIL_ADDRESS] (M.P.P. ); [EMAIL_ADDRESS] (P.C.P. ); [EMAIL_ADDRESS] (P.C.P. ); [EMAIL_ADDRESS] (E.C. ); [EMAIL_ADDRESS] (S.M.R. ); [EMAIL_ADDRESS] (M.A.C.) Christy Research Council of Canada, Department of Chemistry, University of Texas and Athens, 2009, USA; chulta.figueira@gruponabeiro. Different gas chromatography (GC)-based approaches, mainly using mass spectrometers (MS) as detectors, have contributed to highlight the high complexity of the aroma of different coffee matrices, thus allowing identification of more than 800 volatile compounds belonging to different chemical families [5; 6]; namely, pyrazines, pyridines, pyrroles, furrans, volatile phenols, oxazoles, thiophenes, thiazoles, thiols and other sulfur compounds, ketones, alcohols, aldehydes, esters, lactones, alkanes/alkenes, and carboxylic acids, directly in roasted coffee beans [7; 8; 9] or in ground coffee [10; 11; 12], as well as in different kinds of coffee brews, which include espresso coffee [12; 13; 14; 15; 16; 17]. Most of these aroma constituents arise during the roasting of the coffee that potentiate the occurrence of caramelization, and/or Maillard reactions derived from green bean non-volatile compounds [18]. The aroma constituents may also result from the wet fermentation process. Moreover, coffee bean varietal compounds, such as the terpenic ones, can survive the roasting process, being also present in roasted coffee beans and brews, contributing to the final complex coffee aroma [19; 20; 21]. Coffee brews may be obtained using different extraction methods, among which the single-dose capsules system is a device adopted worldwide [22] to prepare espresso coffee, whose use has grown hugely over the years [23]. Its popularity relies on (i) the ready-to-use capsules that simplify the preparation, avoiding the need for grinding or measuring the amount of powder to prepare the brew, bringing convenience and diminishing human variation error, (ii) the reproducibility of extraction conditions [24], and (iii) the diversity of capsule blends that offers a plurality of options to consumers regarding flavors and aromas of the brews. Thus, the consumer may perceive, in a few seconds, the flavor of the brew and the creamy foam layer of an espresso coffee brew [25].