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coffea_canephora_pierre_ex_froehner [2016/05/12 09:59]
andreas
coffea_canephora_pierre_ex_froehner [2016/05/12 10:46]
andreas
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 „The volatile components of roasted Arabica and Robusta coffees (powder and brew) were analysed by gas chromatography-olfactometry (GC/O) which revealed the odorants having the highest odor-activity values (ratio of concentration to odor threshold). This procedure resulted in 38 odorants of which 32 were identified. The powders of the two coffee varieties differed in the concentration levels of these compounds. The results indicate that the flavor difference between Arabica and Robusta coffee (powder and brew) are mainly due to the predominance of enoloxo compounds (sotolon, abhexon, furaneol, 3,4-dimethyl-2-hydroxy-2-cyclopentene-1-one) in the former and of 3,5-dimethyl-2-ethylpyrazine, 2,3-diethyl-5-methylpyrazine, 4-ethylguaiacol and 4-vinylguaiacol in the latter. Preparation of brews enhanced the flavor difference, as the concentration levels of water-soluble odorants (furaneol, sotolon, abhexon) responsible for the “sweet-caramel” flavour note increased more in the Arabica than in the Robusta coffee. On the other hand, the alkylpyrazines and guaiacols were responsible for the “spicy, harsh-earthy” aroma of the Robusta coffee. Quantification of selected odorants using a stable isotope dilution assay confirmed the differences between the Arabica and Robusta coffees (brew) found by GC/O.“ \\ „The volatile components of roasted Arabica and Robusta coffees (powder and brew) were analysed by gas chromatography-olfactometry (GC/O) which revealed the odorants having the highest odor-activity values (ratio of concentration to odor threshold). This procedure resulted in 38 odorants of which 32 were identified. The powders of the two coffee varieties differed in the concentration levels of these compounds. The results indicate that the flavor difference between Arabica and Robusta coffee (powder and brew) are mainly due to the predominance of enoloxo compounds (sotolon, abhexon, furaneol, 3,4-dimethyl-2-hydroxy-2-cyclopentene-1-one) in the former and of 3,5-dimethyl-2-ethylpyrazine, 2,3-diethyl-5-methylpyrazine, 4-ethylguaiacol and 4-vinylguaiacol in the latter. Preparation of brews enhanced the flavor difference, as the concentration levels of water-soluble odorants (furaneol, sotolon, abhexon) responsible for the “sweet-caramel” flavour note increased more in the Arabica than in the Robusta coffee. On the other hand, the alkylpyrazines and guaiacols were responsible for the “spicy, harsh-earthy” aroma of the Robusta coffee. Quantification of selected odorants using a stable isotope dilution assay confirmed the differences between the Arabica and Robusta coffees (brew) found by GC/O.“ \\
 [Aroma impact compounds of arabica and robusta coffee. Qualitative and quantitative investigations. Blank, I., Sen, A.,Grosch, W., In Quatorzieme colloque scientifique international sur le cafe, San Francisco, 14-19 juillet 1991, 117-129)]  [Aroma impact compounds of arabica and robusta coffee. Qualitative and quantitative investigations. Blank, I., Sen, A.,Grosch, W., In Quatorzieme colloque scientifique international sur le cafe, San Francisco, 14-19 juillet 1991, 117-129)] 
 +
 +|{{:2-ethyl-3_5-dimethylpyrazine.jpg|2-ethyl-3,5-dimethylpyrazine}} \\ 2-ethyl-3,5-dimethylpyrazine |{{4-vinylguaiacol.jpg|4-vinylguaiacol}} \\ 4-vinylguaiacol |{{:2methylisoborneol.jpg|2-methylisoborneol}} \\ 2-methylisoborneol |
  
 In various roasted Robusta coffee samples, 2-methylisoborneol was found at 120-430 ng/kg (dry matter) and assigned as earthy smelling character impact compound. \\ In various roasted Robusta coffee samples, 2-methylisoborneol was found at 120-430 ng/kg (dry matter) and assigned as earthy smelling character impact compound. \\
coffea_canephora_pierre_ex_froehner.txt · Zuletzt geändert: 2016/05/12 10:47 von andreas