Phenolic composition of BRS Violeta red wines produced from alternative winemaking techniques: relationship with antioxidant capacity and sensory descriptors

BRS Violeta (BRS Rúbea × IAC 1398-21) grape juice powder produced by foam mat drying. Part I: Effect of drying temperature on phenolic compounds and antioxidant activity

The BRS Violeta grape presents pulp and skin with high content of phenolic compounds (PCs) and intense purplish color. It was used as raw material for the production of juice and dehydrated products using foam mat drying at 60, 70 and 80 °C and freeze drying (control). HLPC-DAD-ESI-MSⁿ allowed the evaluation of the quantitative and qualitative changes of the main PCs (anthocyanins, flavonols and hydroxycinnamic acid derivatives (HCAD)) present in the grapes during the processing. The use of the steam extraction method to obtain grape juice allowed a greater extraction of flavonols and, mainly derivatives of hydroxycinnamic acids, when compared with anthocyanins. Drying at 70 °C was the most suitable for the preservation of the PCs and, at the same time, for the reduction of the processing time. The powdered products presented considerable concentrations of total PCs (3-5 mg/g) and antioxidant activity (32-79 (DPPH) or 17-27 (FRAP) mg/g).

Production of pyranoanthocyanins using Escherichia coli co-cultures

Hydroxyphenyl-pyranoanthocyanins are one of the pyranoanthocyanins found in red wines and some fruit juices. Since they have a fourth ring (pyran or ring D) which provides higher color intensity and exceptional stability toward pH variations in comparison to their anthocyanin precursors, these molecules are one of the most important candidates as natural colorants especially for low- and medium-acidic food and beverages. However, their isolation and characterization are difficult due to their very low concentration. In this study, we co-cultured recombinant E. coli strains to synthesize pyranoanthocyanins with improved titers and yields. To accomplish this task, firstly we engineered 4-vinylphenol and 4-vinylcatechol producer modules then we co-cultured each one of these strains with cyanidin-3-O-glucoside producer recombinant cells to obtain pyranocyanidin-3-O-glucoside-phenol (cyanidin-3-O-glucoside with vinylphenol adduct) and pyranocyanidin-3-O-glucoside-catechol (cyanidin-3-O-glucoside with vinylcatechol adduct). By optimizing the co-culture conditions, we were able to significantly increase final titers and yields, allowing our co-culture approach to easily outperform production of pyranoanthocyanins from red wine. Finally, we demonstrate that the produced pyranoanthocyanins are far more stable than the starting plant-produced cyanidin 3-O-glucoside.

First chemical and sensory characterization of Moribel and Tinto Fragoso wines using HPLC-DAD-ESI-MS/MS, GC-MS, and Napping® techniques: comparison with Tempranillo

BACKGROUND

Due to the current dominance of a few grape varieties in the wine market, the aim of this work was to study the detailed phenolic and volatile composition, chromatic characteristics, and sensorial properties of red wines elaborated with new Vitis vinifera grapes (Moribel and Tinto Fragoso) identified using the High Perfomance Liquid Chromatography-Diode Array Detector-Electrospray Ionization-Tandem Mass Spectrometry (HPLC-DAD-ESI-MS/MS), Gas Chromatography- Mass Spectrometry (GC-MS), CIELab color space, and Napping ® techniques.

RESULTS

Tinto Fragoso wine showed higher phenolic content than Moribel, with more anthocyanins, flavonols, and stilbenes. These wines also contained anthocyanin diglucosides not reported for Vitis vinifera wines. The odor activity values of free volatile compounds were calculated to indicate their influence on wine aroma, the fruity aromas of Moribel standing out particularly. The wines studied were positively evaluated by the tasters. Moribel's sensory profile was characterized by red fruit aromas and Tinto Fragoso showed more aromatic intensity and persistence in the mouth.

CONCLUSION

The results obtained from the first characterization of red wines made from novel Vitis vinifera grapes suggest that Moribel and Tinto Fragoso could be appropriate raw materials for the elaboration of quality young red wines. Tinto Fragoso provided wines with sensorial properties different from those of Tempranillo, and could be an alternative to the well known red wines on the market. © 2018 Society of Chemical Industry.