Vinhos comerciais do Vale do São Francisco : efeitos das condições de armazenamento sobre a estabilidade fenólica e cromática

Abstract

The São Francisco Valley, located in the Brazilian Northeast produces young wines and for fast consumption, such as sparkling wines and red wines. In these wines, phenolic compounds have an important role in the quality of the wine, this way, besides the vinification protocols adequate to the extraction of these compounds, the maintenance of the latter in the wine after bottling requires control of the temperature and luminosity during the storing and transport. The aim of this study was to evaluate the effects of temperature and luminosity on the phenolic and chromatic stability of commercial red wines from São Francisco Valley during storage by means of spectrophotometric and chromatographic analyzes. Thirty-six bottles of commercial wines of four varieties (Cabernet Sauvignon, Syrah, Tannat and Ruby Cabernet) produced in two wineries located in the São Francisco Valley were evaluated for the following parameters: total polyphenols (using Folin- Ciocalteu reagent), index of polyphenols (absorbance at 280 nm), total anthocyanins, intensity and color hue, as well as pH, total titratable acidity and phenolic profile by high performance liquid chromatography (HPLC) with absorbency detector UV/Vis (CLAE UV/Vis). The samples were divided into 5 groups: T0: open and analyzed samples on the same day; CIA: samples stored under ideal conditions of storage (horizontal position, temperature of 16 ° C ± 1 ° C) for 30 days; TC: samples stored at 30°C for 30 days in horizontal position, in an oven; LUV: samples placed in a photostability chamber (horizontal position) for 15 hours to simulate exposure to ultraviolet radiation and TCLUV: samples placed in an oven at 30 ° C for 30 days (horizontal position ) and then taken to the photostability chamber for 15 hours (horizontal position). The data were submitted to analysis of variance (ANOVA) and the means were compared by the Tukey test (p <0.05) using Statistic software 7.0 (Stat-Soft, Tulsa, OK, USA). Principal Component Analysis (PCA) was applied to group and classify wines according to phenolic and chromatic characteristics, cultivars, and storage conditions (temperature and radiation). All wines had high concentrations of phenolic compounds in the T0 group, but all lost it with storage, even in ideal conditions. The wines of Cabernet Sauvignon suffered similarly in terms of storage temperature and ultraviolet radiation, while Syrah wines are highly sensitive to temperature, and Ruby Cabernet wines have a high sensitivity to ultraviolet radiation. Nevertheless, all the wines have suffered in a greater or lesser degree with the storage conditions when we evaluate the phenolic profile and observed significant loss of beneficial compounds to health. The Principal Components Analysis grouped and classified the wines satisfactorily.