Filter, Fourier Transform Infrared, and Areometry, for Following Alcoholic Fermentation in Wines

Areometry, filter near infrared spectrometry (FIR), and Fourier transform near infrared spectrometry (FTIR), have been compared for following total sugar and ethanol during fermentations. Standard errors of calibration (SEC) and prediction (SEP) have been estimated, respectively, with 4 and 2 fermentations, using as reference sugar and ethanol enzymatic analysis. With the first 4 fermentations, the least rectangles method was applied for a more thorough comparison between FIR, FTIR, and areometry. FIR was more complex and more accurate than density measurement, and less complex, but as accurate as FTIR spectrometry. Small SEP can be achieved with FIR spectrometry: 2.5 g/L for total sugars and 0.15% (v/v) for ethanol.