promising

stable, reddish-brown, pervaded by wispy, lighter stripes (tiger-skin effect)
consolidates itself even after vigorous stirring

chemical composition in ppm includes

• ethylgujacol 1.2
• 2-ethyl-3,5-dimethylpyrazin 0.9
• 2-ethyl-3,6-dimethylpyrazin 0,8
• 2,4-decadienal 0,7
• 2,4-nonadienal < 0.5
• methylsalicylat < 0.5
• dimethyl trisulfide (DMTS) < 0.5
• isovaleraldehyde < 0.5
• α-ionon < 0.5
• linaloole < 0.5

overextracted espresso

dark brown, hole or white spot in the middle
– too fine grind

– too much coffee powder

– too hot water temperature

– too long brewing time

– too firmly tamped filter cake

• ethylgujacol 2.1
• 2-ethyl-3,5-dimethylpyrazin 1.3
• 2-ethyl-3,6-dimethylpyrazin 1.2
• 2,4-decadienal 2.6
• 2,4-nonadienal < 0.8
• methylsalicylat < 0.8
• dimethyl trisulfide (DMTS) < 0.8
• isovaleraldehyde < 0.8
• α-ionon < 0.8
• linaloole < 0.8

underextracted espresso

light, thin, unstable

– too coarse grind

– too little coffee powder

– too low water temperature

– too short brewing time

– too old beans

• ethylgujacol 0.6
• 2-ethyl-3,5-dimethylpyrazin 0.8
• 2-ethyl-3,6-dimethylpyrazin 0,8
• 2,4-decadienal 0,3
• 2,4-nonadienal < 0.3
• methylsalicylat < 0.3
• dimethyl trisulfide (DMTS) < 0.3
• isovaleraldehyde < 0.3
• α-ionon < 0.3
• linaloole < 0.3