In order to check the feasibility of NIRS method developed in
this study, one apple wine fermentation trail was monitored by the
calibration models. The alcohol strength and titratable acidity with
time during the apple wine fermentation were predicted using
NIRS calibration and also measured by the chemical reference
methods. The analyses of results are presented in Fig. 6. Fig. 6 shows
that the R2 for the predicted versus measured values of the alcohol
strength and titratable acidity were 0.962 and 0.972, respectively.
The RMSEP of the alcohol strength and titratable acidity were
3.6 mL/L and 0.22 g/L, respectively. The predicted and measured
values of the alcohol strength and titratable acidity showed similar
variations over the entire fermentation period. All these resultssuggest that the calibration models have good predictive capacity
for alcohol strength and titratable acidity during apple wine
fermentation, and this rapid NIR method could be taken to monitor
the apple wine fermentation process with sufficient feasibility.