Feasibility study on the use of attenuated total reflectance mid-infrared for analysis of compositional parameters in wine

A simple and fast method was developed for simultaneously determining ethanol, specific gravity (SG), volatile acidity (VA), glucose plus fructose (G + F), pH and titratable acidity (TA) in commercial Australian red and white wine samples using mid-infrared (MIR) spectroscopy and attenuated total reflectance (ATR). Wine samples (n = 130) were analysed using an MIR instrument equipped with a single bounce ATR cell. Results from this study demonstrated the capability of ATR-MIR coupled with partial least squares (PLS) regression to measure compositional parameters in wine. The standard errors of prediction (SEP) obtained were of 0.11 (%) for ethanol, 0.0007 for SG, 0.10 for pH, 0.53 g/L for TA, 1.35 g/L for G + F, and 0.12 g/L for VA. Both the sample preparation time of analysis and volume of sample required were considerably reduced compared to the transmission MIR measurements currently used by the wine industry.