Model Studies on the Influence of Coffee Melanoidins on Flavor Volatiles of Coffee Beverages

Abstract

Addition of the total melanoidin fraction isolated by water extraction from medium-roasted coffee powder to a model solution containing a set of 25 aroma compounds mimicking the aroma of a coffee brew reduced, in particular, the intensity of the roasty, sulfury aroma quality. Model studies performed by static headspace analysis revealed that especially three well-known coffee odorants, that is, 2-furfurylthiol (FFT), 3-methyl-2-butene-1-thiol, and 3-mercapto-3-methylbutyl formate, were significantly reduced in the headspace above an aqueous model solution when melanoidins were added. In particular, the low molecular weight melanoidins (1500-3000 Da) led to the most significant decrease in FFT. In contrast, for example, aldehydes remained unaffected by melanoidin addition.

HS-SPME/GC/MS profiles of convectively and microwave roasted Ivory Coast Robusta coffee brews

“…In the brews of Arabica coffee, their contents were twice as high as in the presented brews of Robusta coffees. Hofmann et al (2001) postulated that another furan derivative -2,5-dimethyl-4-hydroxy-3(2H)-furanone, ranks among the key contributors to the coffee aroma with a very low odour threshold (160 μg/kg water) and a sweet, caramel-like hint. Its concentration was the highest in the headspace of brews prepared from CMR samples of coffee (Table 1, No.…”

“…Both of them are unique and significant contributors to the aroma of a cup of coffee (Clarke 1990;Hofmann et al 2001). According to Mayer et al (2000) the extractability of guaiacol and ethylguaiacol is 65% and 50% and their odour activities are 490 and 13, respectively.…”

The protective effects of melanoidins in adriamycin‐induced oxidative stress in isolated rat hepatocytes

“…25 Briefly, 0.05 mol of both glucose and glycine were dissolved in 100 ml of water, frozen, freeze-dried overnight and heated at 125 • C for exactly 2 h. Distilled water (20 ml) was added to 5 g of the product and stirred to dissolve as much material as possible. The mixture was filtered and the filtrate collected and dialysed at 4 • C with double-distilled deionized water.…”

Free Radical Processes in Coffee II—Liquids

“…However, investigations combining instrumental analyses with human olfactory perception (e.g., GC/olfactometry) have revealed a rapid decrease in the concentrations of odor-active thiols at elevated temperature. Examples include the manufacturing of instant coffee (Semmelroch and Grosch, 1995), heat sterilization of coffee beverages (Kumazawa et al, 1998), or keeping a freshly prepared coffee brew warm in a thermos flask (Hofmann et al, 2001). Concentrations of 2-furfurylthiol, a key coffee odorant in R&G coffee, are significantly reduced, and a strong decrease of the sulfury-roasty odor quality in the overall aroma of coffee beverages is observed (Hofmann et al, 2001).…”

“…Examples include the manufacturing of instant coffee (Semmelroch and Grosch, 1995), heat sterilization of coffee beverages (Kumazawa et al, 1998), or keeping a freshly prepared coffee brew warm in a thermos flask (Hofmann et al, 2001). Concentrations of 2-furfurylthiol, a key coffee odorant in R&G coffee, are significantly reduced, and a strong decrease of the sulfury-roasty odor quality in the overall aroma of coffee beverages is observed (Hofmann et al, 2001). Furthermore, reactions involving the melanoidin components have been implicated in these changes (Hofmann et al, 2001;Hofmann and Schieberle, 2002).…”