The effect of different cooling techniques (air cooling or liquid nitrogen cooling) on volatile and aroma active compounds of antakya coffee

Antakya coffee is a traditional coffee that is subject to a higher roasting temperature than Turkish coffee; thus, it is darker and bitter. Depending on the ambient temperature, the effectiveness of air cooling fluctuates resulting in difficulty in controlling the aroma profile and flavor of Antakya coffee. In this study, therefore, the volatile and aroma active compounds of Antakya coffee which were immediately cooled either by air (HS) or in liquid nitrogen (SAS) were determined. Volatiles were extracted using a high vacuum distillation technique and analyzed by gas chromatography-mass spectrometry for volatiles and gas chromatography-olfactometry techniques for aroma active compounds. The results showed the presence of a total of 9 aliphatic, 8 homocyclic and 32 heterocyclic volatile compounds in the coffee samples. The volatile component was determined as 19.73 mg kg-1 in AS and 19.71 mg kg-1 in SAS samples. The applied cooling applications did not have a significant effect on the total amount of volatile components (p>0.05). Furans were the chemical group with the highest amount detected in volatile compounds. Furans constituted 44.15% of the total volatile components in HS samples and 45.20% in SAS samples. The furans were followed by pyrazines and pyrroles, respectively. A total of 28 aroma active ingredients were determined in the olfactometer port. 27 aroma active components were determined in HS samples and 19 in SAS samples. 9 of the aroma active compounds (thiophene, propanoic acid, 2-formyl-1-methyl pyrrole, 2-ethyl-6-methyl-pyrazine, phenol, 2-acetylpyrrole, 2-methoxy phenol, 3-ethyl-2-hydroxy-2- cyclopentene-1-one, 3-hydroxy-2-methyl-4H-pyran-4-one) was detected only in HS, while indole was detected only in SAS coffee samples. Thiophene and 2-isobutyl-3-methoxypyrazine compounds that could not be detected in GC-MS were also detected in the olfactometer port. Thiophene imparts an 'onion' flavor only to air-cooled coffee (HS), while 2-isobutyl-3-methoxypyrazine imparts a 'green pepper' flavor to coffees cooled in both ways. 2021, 41 pages Key Words: Antakya coffee, cooling, liquid nitrogen, volatile compounds, aroma active compounds