Rapid detection of volatile compounds in apple wines using FT-NIR spectroscopy.

The purpose of this work was to study the possibility and ability of NIR spectroscopy to determine the volatile compounds in apple wines. To achieve this, seventy-two samples were scanned using NIR transmission spectroscopy. The volatile compounds were analyzed using HS-SPME-GC-MS. Partial least square (PLS) regression with full cross-validation was applied to develop the calibration models. The calibration results using 42 apple wine samples had a coefficient of determination in full cross validation (Rcv(2)) between 0.8916 for hexanol and 0.8278 for 3,4,5-trimethyl-4-heptanol. The predictive ability of the models was further confirmed by external validation procedure with an independent sample set which did not belong to the calibration group. The resulting values of Rp(2) ranged from 0.9184 for ethyl hexanoate to 0.8811 for 2-phenethanol and 3,4,5-trimethyl-4-heptanol. The residual predictive deviation (RPD) obtained was higher than 2.9 in all the compounds. The results demonstrate that near infrared spectroscopy can be used as a rapid tool to determine the volatile compounds in apple wines.