Evaluation of natural occurring bioactive compounds and antioxidant activity in Nuragus white wines

Bioaccessibility of polyphenols and antioxidant properties of the white grape by simulated digestion and Caco-2 cell assays: Comparative study with its winemaking product

The primary objective of this study was to assess the changes on phenolic composition and AC (antioxidant capacity) of white grape and its winemaking product, during in vitro gastrointestinal (GI) digestion. Phenolic compounds were evaluated by HPLC-MS/MS. The AC was measured by in vitro (FRAP, ABTS and DPPH) and cellular (Caco-2 cells) assays. Digestion had a reducing effect on phenolic content, being only 31% and 67% of native polyphenols from grapes and wines, respectively, potentially bioaccessible. At same polyphenol concentration, cellular AC of nondigested and digested foods was the same, indicating that changes in phenolic profile did not modify the bioactivity. Phenolic acids, in addition to quercetin, were the most resistant polyphenols to digestion, and would be the most relevant to explain the biological activity of digested foods. Results indicate that the changes occurred in the native phenolic profile of foods as a consequence of GI digestion, do not modify the bioactivity of white grapes and wines.

Insight into the Chemical Diversity of Late/Ice Harvest Gewürztraminer Wine

Late harvest (LHW) and ice harvest (IHW) Gewürztraminer wine samples from Croatia (Ilok) were investigated. Their technological parameters, chromaticity coordinates, total phenols content, and antioxidant capacity were determined. 5-(Hydroxymethyl)furfural, xanthine, and trans-caftaric acid were analyzed in the samples by high performance liquid chromatography (HPLC-DAD). Headspace solid-phase microextraction (HS-SPME) followed by gas chromatography and mass spectrometry (GC/MS) analysis revealed isoamyl alcohol as predominant compound (21.25 - 60.30%). Diethyl succinate, 2-phenylethanol, and benzaldehyde were also abundant. Ethyl octanoate (1.48 - 5.70%) and ethyl caprate (0.48 - 4.83%) decreased significantly in LHW, being the lowest in IHW. Two solvents were applied for the samples extraction (solvent A - pentane/diethyl ether 1:2 (v/v) and solvent B - dichloromethane), and the extracts were analyzed by GC/MS. Ethyl hydrogen succinate (solvent A: 27.30 - 52.04%; solvent B: 28.04 - 46.69%) and diethyl succinate (solvent A: 5.21 - 18.2%; solvent B: 2.66 - 7.72%) were predominant in IHW and LHW. Aromatic alcohols were also found: 2-phenylethanol (solvent A: 7.07 - 21.09%; solvent B: 5.50 - 11.82%), 4-hydroxybenzyl alcohol (solvent A: 1.45 - 6.68%; solvent B: 2.47 - 12.16%) and benzyl alcohol (solvent A: 0.10 - 0.77%). The obtained results complement a previous study on IHW (Gewürztraminer) from Croatia providing new features and indicating great chemical diversity among the samples.