Multivariate Methods for Characterization and Classification of Espresso Coffees from Different Botanical Varieties and Types of Roast by Foam, Taste, and Mouthfeel

Abstract

Three espresso coffee (EC) samples of different botanical varieties and types of roast were prepared in standard conditions using an experimental EC prototype: Arabica coffee, Robusta Natural blend, and Robusta Torrefacto blend (a special roast by adding sugar). The ECs were characterized with regard to the physical parameters, amount of total solids, total solids on filtrate, lipids, caffeine, trigonelline, and chlorogenic acids by HPLC, and sensory descriptive analysis related to foam appearance, taste, and mouthfeel. Principal component analysis (PCA) was applied to differentiate the EC samples. Arabica and Robusta samples were separated successfully by principal component 1 (55.3% of variance) including physicochemical and sensory parameters related to foam and taste of ECs. Torrefacto and Robusta Natural EC samples were separated by principal component 2 (20.7% of total variance) including mouthfeel and other attributes of color foam. Some interesting correlations among sensory and physicochemical variables were found. A very simple discriminate function was obtained by discriminate analysis allowing the classification of each EC sample into its respective group with a success rate of 100%.

Effect of ultra high temperature (UHT) treatment on coffee brew stability

“…Six aldehydes, 4 ketones and 1 acid were identified and quantified in the headspace of the coffee brews. Methanethiol, a sulphur compound related to aroma freshness in ground roasted coffee (Holscher, & Steinhart, 1992) and espresso coffee (Maeztu et al, 2001a) was found. Nor guaiacol (2-methoxyphenol), responsible for phenolic, spicy and burnt aromas and flavors (Blank et al, 1991;Semmelroch, & Grosch, 1995), was present at detectable levels in the studied coffee brews.…”

“…Afterwards, the area of 2-propanone and 2-butanone tended to increase until the end of the storage time, reaching values significantly higher than the initial ones. In contrast, 2,3-butanedione and 2,3-pentanedione, key odorants responsible for the buttery flavors in espresso and other coffee brews (Maeztu et al, 2001a;Blank et al, 1991;Semmelroch, & Grosch, 1996), showed a decrease with storage time. This fact could be related to the aroma freshness loss in coffee brews after the the first 8 days of storage.…”

“…The profiles of volatile compounds were obtained with the method described by Sanz, Ansorena, Bello, & Cid (2001), adapted to coffee brew by Maeztu et al (2001a), and using Static Headspace-Gas Chromatography-Mass Spectrometry (SH-GC-MS).…”

Effects of refrigeration and oxygen on the coffee brew composition

“…The freshly prepared coffee brews were immediately poured into 330 mL sterilized glass flasks, either up to a volume of 135 mL (with air headspace, this is, Caffeine and Trigonelline. Extract preparation, clean-up and HPLC analysis were performed following the method described by Maeztu et al [22]. HPLC analysis was achieved with an analytical HPLC unit (Agilent Technologies 1100), equipped with a binary pump and an automated sample injector.…”

Green and roasted arabica coffees differentiated by ripeness, process and cup quality via electrospray ionization mass spectrometry fingerprinting

“…1 Most studies on differentiation deals with Arabica and Robusta green and roasted coffees in relation to their major chemical composition such as metal, 2 lipids focused on sterolic and alcohol diterpenes, 3 alkaloids, 4 chlorogenic acids 5 and sugar profiles. 6 Chemometric discrimination using principal component analysis (PCA) has been successfully used as an important tool to differentiate roasting processes, 7 geographical origin of green and roasted coffees 8 and other aspects of coffee process. To search for faster methods for coffee discrimination based on fingerprinting analysis, NIR and NMR studies were also applied.…”