A Study of the UV Spectral Features in Wine and Their Correlation with Phenolic Constituents
Joel B. Johnson, Ruslan Timofeev, Anatoliy Kazak, Yurij Grishin, Ludmila Solovyova, Мarina Rudenko
Abstract
BACKGROUND: This study investigated the ultraviolet (UV) absorption spectra of various types and ages of grape wines and the correlation these spectra presented with their phenolic constituents. Firstly, the differences in UV spectra were characterized for different wine samples, depending on their type and age. METHODS: The following methods were used in this study: ultraviolet visible spectrophotometry, Folin-Ciocalteu spectrophotometric method, high-performance liquid chromatography. RESULTS: Then, it was demonstrated that for identically aged wines, the 280 nm absorbance is proportional to the concentration of phenolic compounds, as determined by the Folin-Ciocalteu method. Next, an investigation was conducted into the absorption coefficients of different phenolic classes commonly found in grapes and wine. Finally, the range in variation of phenolic compounds in various types of grape wines was established. CONCLUSIONS: This work provides a methodological approach to rapidly determine the concentration of phenolic compounds in wines using UV spectroscopy, provided that their age is known. As UV spectrophotometers are available in nearly all laboratories, this may provide a cheaper and faster alternative to current methods, including high-performance liquid chromatography (HPLC).