Measurement of Color, Refractive Index, and Turbidity of Red Wines

Abstract

Optical properties of red wine can be used to characterize wine. A traditional optical measurement involves red wine color obtained from the light transmission spectrum. Red wine color is not the only optical indicator; the refractive index and turbidity of the wine may also be used for a more comprehensive analysis. The purpose of this study was to introduce a combination of optical measurements based on recording the transmission and reflection spectra and turbidity of red wines and relevant data analysis. A multifunction reflectometer is introduced for red wine inspection. Transmittance, color, refractive index, reflectance, and turbidity of 12 commercial red wines from different countries were studied to test the scheme of their multiple optical measurements. Incorporating different types of optical measurements of red wine may identify different stages of the winemaking process and aid in authenticating the wine. In addition to color, refractive index, and turbidity, moments obtained from reflection and refractive index spectra are introduced as novel parameters to characterize the optical properties of red wine.