Contribution of volatile compounds to the antioxidant capacity of coffee

Abstract

Heterocyclic volatile compounds present in coffee have been proposed as potent antioxidants, but their contribution to the antioxidant capacity of coffee is still unclear and controversial. The aim of this study was to assess the actual contribution of the main volatile compounds to the overall antioxidant capacity of coffee. A total of sixty-two and sixty-four volatile compounds were identified and quantified in Arabica and Robusta coffee, respectively, by static headspace-gas chromatography-mass spectrometry (SH-GC-MS). ABTS (2,2'-Azino-bi(3-ethylbenzo-thiazonile-6-sulfonic acid) diammonium salt) and DPPH (2,2-Diphenyl-1-picrylhydrazyl) antioxidant activity of the most abundant volatile heterocyclic compounds (7 furans (Fu), 3 pyrroles (Py) and 2 thiophenes(Th)), aldehydes (5) and diketones (2) was evaluated in model systems at different concentrations including those found in coffee. The model system with all the heterocyclic volatiles (Fu-Py-Th) was the most active followed by pyrroles and furans. Thiophenes were ineffective as radical scavengers at all concentrations including 100-fold, and aldehydes and ketones showed negligible activities in comparison to heterocyclic volatiles. In addition, only furans exhibited linear concentration dependent ABTS antioxidant activity and individual volatiles model systems showed that only 2-methyl-tetrahydrofuran-3-one and pyrrole for ABTS, and also 1-methylpyrrole for DPPH, were the main volatile compounds responsible for the coffee antioxidant activity. However, the contribution of the heterocyclic volatile compounds to the overall antioxidant capacity of a filter coffee brew was almost insignificant, even at 100-fold concentrated Fu-Py-Th model system, accounting only for up to 3.3%.

The Effect of Gravity-Drip Filtration Methods on the Chemical and Sensorial Properties of Coffee (Coffea Arabica L. Var. Castillo)

“…Antioxidant activity and the concentration of these metabolites depend on factors such as the degree of coffee milling, the coffee/water ratio, temperature, and extraction time involved with the method used in beverage preparation (NISETEO et al, 2012). ABTS antioxidant activity measured in coffees filters with C. arabica coffee presented values similar to those reported in the present study (LUDWIG et al, 2014;JESZKA-SKOWRON et al, 2016). Another, which compared a coffee filtered with other traditional preparations (Napolitano, Mocha, and Expresso), in terms of phenolic compounds and ABTS activity concentration, found a lower concentration, and the lowest antioxidant activity in filtered coffee, owing to parameters such as temperature and pressure, which promote greater performance in extraction in methods such as Mocha, Napolitano, and Expresso (Caporaso et al, 2014).…”

Identification of Volatile Compounds and Selection of Discriminant Markers for Elephant Dung Coffee Using Static Headspace Gas Chromatography—Mass Spectrometry and Chemometrics

“…Alternatively, static headspace (SHS) sampling can be simply performed to extract volatile compounds from coffee samples without the use of specific solid-phase materials. By this method, all volatile compounds are introduced into the GC-MS system [ 19 , 22 , 26 , 27 , 28 ]. In some cases, gas chromatography-olfactometry (GC-O) with a sensory evaluation by panelists has been used for the identification of key odorants in coffee [ 29 , 30 ].…”

Contribution of aroma compounds to the antioxidant properties of roasted white yam (Dioscorea rotundata)

“…Analysis of volatiles was carried out using the Static headspace-gas chromatography-mass spectrometry (SH-GC-MS) as reported by Ludwig, et al, [5]. The roasted extract (4 mL) or volatile standards solution (4 mL) was introduced into a 10 mL vial and sealed with a silicon rubber Teflon (Table 1) was done comparing their mass spectra with the spectra of the available pure standards and also by comparing their retention indices with those of standards and data from literature.…”