Analysis of Freshly Brewed Espresso Using a Retronasal Aroma Simulator and Influence of Milk Addition

Abstract

A quick (headspace: 1 min and retronasal aroma simulator (RAS): 2 min) sampling method for capturing volatiles released from coffee drinks by solid-phase microextraction (SPME) (fiber type; divinylbenzene (DVB)/carboxen/polydimethylsiloxane (PDMS)) has been applied to freshly brewed espresso and café latte (espresso and milk). Headspace volatiles and volatiles in the RAS effluent were collected from espresso and café latte, and examined by gas chromatography/mass spectrometry (GC/MS) and GC/olfactometry (GC/O, CharmAnalysis™). When milk was added to espresso in 60% by weight, aroma release (odor activities) was generally suppressed, both in headspace and RAS aromas. The relative charm value of sweet-caramel odor increased in the headspace aroma, while the phenolic odor increased markedly and the smoke-roast odor decreased in the RAS aroma. These results suggested that milk addition had different effects on the headspace and RAS aromas.

Changes in Volatile Compounds of an Aseptically Packaged Cup Coffee Beverage during Early Storage at 10°C

“…RA compounds of AC samples stored for 0, 1, and 2 weeks were collected by exposing a SPME fiber to the effluent gas, using a RAS coupled to a SPME fiber of 2 cm length. After sampling for 2 min, the SPME fiber was injected into the GC-O or GC-MS inlet port and the analyte was thermally desorbed for 10 min at 225℃ or 250℃, respectively (Akiyama et al, 2009). Each SPME sample was conducted in triplicate.…”

“…The GC-O analysis by a dilution method which involves varying the split ratio of GC injection was developed by Deibler et al (2004), and has been successfully applied to GC-O analysis of the aromas of freshly brewed espresso coffee (Akiyama et al, 2009). Volatile compounds of the stored sample in the effluent gas of the RAS were thus collected using SPME fibers.…”

“…Acidic, buttery-oily, green-blackcurrant, green-earthy, nutty-roast, phenolic, smokeroast, soy sauce, sweet-caramel, and sweet-fruity were the aroma descriptors used in all GC-O experiments to describe potent odorants. These descriptors were chosen from the results of the previous study (Akiyama et al, 2009). The sensory significance of each odorant was evaluated and expressed as flavor dilution (FD) factor (Schieberle and Grosch, 1987).…”

Effect of Milk Components on Release of Retronasal-aroma Compounds from Coffee with Milk

“…The blending amount or composition of milk (i.e., milk components) in a milk-coffee beverage reportedly influences both the quantity and quality of coffee flavor compounds released (Bücking and Steinhart, 2002;Denker et al, 2006;Parat-Wilhelms et al, 2005;Akiyama et al, 2009). In addition, the content of milk fat (MF) and the lipophilicity (i.e., hydrophobicity) of flavor compounds reportedly affect flavor release (Roberts et al, 2003a(Roberts et al, , 2003bMiettinen et al, 2004;Relkin et al, 2004;Frank et al, 2012).…”

“…An RA simulator (RAS) developed by Roberts and Acree (1995) as one of various mouth models (van Ruth et al, 1994;Roberts and Acree, 1995;Elmore and Langley, 1996) has been used to analyze coffee aromas (Michishita et al, 2010;Watanabe et al, 2012;Akiyama et al, 2014) and how the amount of milk added affects the aroma of coffee beverages (Akiyama et al, 2009). …”