Extraction and evaluation of natural occurring bioactive compounds and change in antioxidant activity during red winemaking

Phenolic composition of red wines from Stanušina, a grape variety indigenous of the Republic of Macedonia, was compared with the regional Vranec and the international Cabernet Sauvignon. The extent of skin contact (i.e. maceration time) on levels of phenolic compounds and antioxidant activity of wines was evaluated. A total of 19 phenolic compounds were identified and quantified. Among these malvidin-3-glucoside and its derivatives were the major compounds, while caftaric acid was the predominant cinnamic acid derivative, followed by catechin, the main flavan-3-ol. The concentration of hydroxycinnamic acids, anthocyanins and (+)-catechin ranged from 224 to 511 mg/L, 22 to 360 mg/L and 26 20 to 375 mg/L, respectively and peaked at 3rd, 6th and 9th day of maceration, respectively. However, prolong maceration slightly decreased their concentration. Stanušina wines presented high levels of hydroxycinnamic acids and antioxidant activity

Application of a Novel Small-Scale Sample Cleanup Procedure Prior to MALDI-TOF-MS for Rapid Pigment Fingerprinting of Red Wines

This study evaluates the anthocyanin and derived pigment composition of Vitis vinifera red wines of Vranec, Merlot, and Cabernet Sauvignon produced in 2006, 2007, and 2008 vintages from the Tikve š wine region in the Republic of Macedonia.Their profile was established using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) technique. A total of 22 anthocyanins and derived pigments have been identified in the samples including 10 anthocyanins, 1 ethyl-bridged flavanol – anthocy- anin adduct, and 11 pyranoanthocyanins. MALDI-TOF-MS analysis was performed after solid-phase extraction of the wines by using, for the first time, the Zip-Tip® C18 stationary phase, introducing a novel small-scale sample cleanup proce- dure prior to the rapid MALDI-TOF-MS fingerprinting of wine samples. 2 ′ ,4 ′ ,6 ′ -Trihydroxyacetophenone (dissolved in acetonitrile/water 1:1, v / v ) was used as a matrix. The qualitative screening of anthocyanins and derived pigments with MALDI- TOF-MS confirmed the presence of glucoside, acetylglucoside, and p -coumaroylglucoside derivatives of anthocyanins in the wine samples. Furthermore, pyranoanthocyanins formed by reactions of anthocyanins with pyruvic acid and acetaldehyde, as well as flavanol – pyranoanthocyanins and ethyl-bridged flavan-3-ol-anthocyanin adduct pigments have been detected in the samples

Fast Analysis of Total Polyphenol Content and Antioxidant Activity in Wines and Oenological Tannins Using a Flow Injection System with Tandem Diode Array and Electrochemical Detections

An analytical method for simultaneous determination of total polyphenol content (TPC) and antioxidant activity (AA) of wines (white and red wines) and oenological tannins, using a flow injection system with sequential diode array and electrochemical amperometry detectors (DAD-ECD), was proposed. The signal at 280 nm provided aggregate data for TPC. The anodic peak related to wine phenolic oxidation was scanned using pulsed integrated amperometry over the potential of 800 mV vs. Ag/AgCl, to obtain AA. Serial dilutions avoided the poisoning at the glassy carbon (GC) electrode and the linear response obtained with both detectors was compared with spectrophotometric assays commonly used in oenology laboratory. Intraday and interday analytical repetitions showed a good repeatability and reproducibility (relative standard deviation RSD < 6% for both detectors), and the satisfactory relationship between the proposed coupled flow injection/DAD-ECD and the classic UV methods (R2TPC = 0.9967; R2DPPH = 0.9621) confirmed the efficacy of flow injection analysis with a coupled detection system, for the reliable quality control of wine and wine-related products