General and some aromatic components of four brands of imported bottled cognac brandy were analyzed.
1. Correlation rates were calculated on twenty chemical components and organoleptic evaluation scores. Close relations were observed among pH, acetal, and organoleptic scores, between total acidity and β-methyl-γ-octalactone, and among ethyl acetate, ethyl caproate, ethyl caprylate, and ethyl caprate.
2. Sum of odor units (concentration/threshold) of some aromatic components correlated with organoleptic scores that of higher fragrant was evaluated as having better quality.
3. Aging years were estimated from the following formula in which average value of phenethyl alcohol at each grade of four brands of cognac brandy is used as variable,
Yn=
Ys+ (1+0.02)
nwhere
n is aging year, 0.02 is annual loss rate during storage in wooden barrel, and
Yn and
Ys are amounts of phenethyl alcohol in
n and s years.
Amounts of the other components were plotted against the assumed aging years to obtain aging curves. On the other hand, concentration at various aging years were calculated by the above formula and plotted against the aging years to obtain the concentration curves.
Differences between the aging curves and the concentration curves showed that the changing pattern of aromatic components during aging greatly varied depending on the balances of evaporation, concentration, or chemical reaction occured during the storage.
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