Analysis of Volatile Compounds, Composition, and Thermal Behavior of Coffee Beans According to Variety and Roasting Intensity

Abstract

This study aimed to investigate the ways in which the thermal behavior, composition, and volatile compound contents of roasted coffee beans depend on variety and roasting intensity. The thermal analysis revealed various transformations in coffee composition, namely, drying, water loss, and decomposition of polysaccharides, lipids, amino acids, and proteins. The results showed that volatile compounds are released differently in coffee depending on coffee type and degree of roasting. The most abundant volatile compounds present in the samples were 2-butanone, furan, 2-methylfuran, methyl formate, 2.3-pentanedione, methylpyrazine, acetic acid, furfural, 5-methyl furfural, and 2-furanmethanol. The total polyphenol contents ranged between 13.3 and 18.9 g gallic acid/kg, being slightly higher in Robusta than in Arabica varieties and in more intensely roasted beans compared to medium-roasted beans. The Robusta variety has higher mineral contents than Arabica, and the contents of most minerals (K, Ca, Mg, Fe, Cu, P, N, and S) increased with roasting intensity. Discrimination between coffee varieties and roasting intensities is possible based on mineral and polyphenol contents.

A Comparative Analysis of Phenolic Content, Antioxidant Activity, Antimicrobial Activity, and Chemical Profile of Coffea robusta Extracts Using Subcritical Fluid Extraction and Supercritical Carbon Dioxide Extraction

“…The GC-MS results revealed that the majority of the chemical compounds were caffeine, which belongs to the purine group and is commonly found in coffee extracts [ 45 ]. However, the amount of caffeine detected in this study was considerably higher than in some previous studies [ 46 , 47 , 48 ]. A previous study also reported that Robusta seeds contain 40–50% more caffeine than Arabica seeds [ 49 ].…”

Utilizing HS-SPME-GC-MS for Regional Classification of Ethiopian Green Coffee Beans: An In-Depth Analysis of Volatile Compounds

“…Similarly, observed a group of alcohols, aldehydes, ketones, esters, hydrocarbons, pyrroles, furans, and other compounds in green Arabica beans. However, no furans were detected in our green samples, and according to, furans are formed during the roasting of the beans through the Maillard reaction. Studies on green coffee have indicated that the majority of volatiles belong to the aldehyde class. ,− The volatile fraction of coffee beans is known to primarily consist of alcohols, acids, esters, and aldehydes .…”

Effects of reduced rainfall on coffee quality and volatile composition

“…Volatiles were collected using a ‘push–pull’ dynamic headspace collection system. Volatiles were collected from unroasted coffee samples to assess the biochemical makeup of each coffee prior to manipulation by the roasting process 24,25 . Coffee samples (3.5 g) were ground in a ball mill (Retsch Mixer Mill MM 400, Verder Scientific Inc., Newton, PA, USA) for 3.5 min and then loaded into glass tubes (2.5 cm i.d., 61 cm long, 300 mL volume) connected to the collection system.…”

“…Volatiles were collected from unroasted coffee samples to assess the biochemical makeup of each coffee prior to manipulation by the roasting process. 24,25 Coffee samples (3.5 g) were ground in a ball mill (Retsch Mixer Mill MM 400, Verder Scientific Inc., Newton, PA, USA) for 3.5 min and then loaded into glass tubes (2.5 cm i.d., 61 cm long, 300 mL volume) connected to the collection system. Purified air was pushed into one end of the tube and pulled via a vacuum pump over the sample and through a glass column connected to the outlet end of the tube.…”