Feasibility of using a miniature NIR spectrometer to measure volumic mass during alcoholic fermentation

Abstract

Volumic mass—a key component of must quality control tests during alcoholic fermentation—is of great interest to the winemaking industry. Transmitance near-infrared (NIR) spectra of 124 must samples over the range of 200–1,100–nm were obtained using a miniature spectrometer. The performance of this instrument to predict volumic mass was evaluated using partial least squares (PLS) regression and multiple linear regression (MLR). The validation statistics coefficient of determination (r²) and the standard error of prediction (SEP) were r² = 0.98, n = 31 and r² = 0.96, n = 31, and SEP = 5.85 and 7.49 g/dm³ for PLS and MLR equations developed to fit reference data for volumic mass and spectral data. Comparison of results from MLR and PLS demonstrates that a MLR model with six significant wavelengths (P < 0.05) fit volumic mass data to transmittance (1/T) data slightly worse than a more sophisticated PLS model using the full scanning range. The results suggest that NIR spectroscopy is a suitable technique for predicting volumic mass during alcoholic fermentation, and that a low-cost NIR instrument can be used for this purpose.

Keywords::

• NIR spectroscopy
• wine
• volumic mass
• partial least squares
• multiple linear regression
• miniature NIR spectrometer

Declarations of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.