Scientific hypothesis is: The total antioxidant capacity and the content of polyphenols and flavonoids in Czech liturgical and common wines are differed.

The aim of the study was a comparison of the antioxidant capacity and the content of polyphenols and flavonoid in Czech liturgical and common wines. Wine samples were selected with respect to their comparability of vintage, subregion and attribute.

For analysis of total antioxidant capacity and the total content of polyphenols and flavonoids in sacramental wines were selected wines Pinot Noir and Red Traminer, Chardonnay was used for comparison in kosher wines. For each variety, 2 samples of common wine and 2 samples of liturgical wine were tested. Samples were chosen to ensure the highest comparability possible (vintage, sub-area and attribute), but different producers. Due to the difficulty of acquiring the comparable samples, their gathering took 15 months.

Samples were bought gradually in the common market, specialized wine shops and directly from the producers. Two bottles of each wine were bought and analysed. The samples in Table 1 were tested.

To determine total antioxidant capacity (TAC) DPPH (1,1- diphenyl -2 picrylhydrazyl) assay was used according to the study by Brand-Williams et al. (1995). The stock solution was prepared by dissolving 24 mg of DPPH with 100 mL of methanol and then stored at -20 °C until needed. The absorbance of DPPH radical without wine was measured daily. The sample solution was obtained by mixing 10 mL of the stock solution with 45 mL of methanol to obtain the absorbance of 1.1 ±0.02 units at 515 nm using the spectrophotometer LIBRA S6 (Biochrom, Cambridge, UK). The wine (210 μL) was allowed to react with 4 mL DPPH solution for 1 hour in the dark. Then, the absorbance was taken at 515 nm. Antioxidant capacity was calculated as a decrease of the absorbance value using the formula:

Antioxidant capacity (%) = (A0 - Ai/A0) x 100%, where A0 is the absorbance of a blank (without the sample) and Ai is the absorbance of the mixture containing the sample. Calculated antioxidant capacity was converted using a calibration curve of the standard and expressed in ascorbic acid equivalents (AAE) (Rupasinghe, Jayasankar and Lay, 2006).

To measure total phenolic content (TPC) Folin-Ciocalteau reagent was used. 0.1 mL of wine was taken and mixed with water in a 50 mL volumetric flask. There-after, 0.5 mL of Folin-Ciocalteau reagent and 1.5 mL of 20% solution of Na₂CO₃ were added. The resulting absorbance was measured by LIBRA S6 spectrophotometer (Biochrom, Cambridge, UK) at the wavelength of 765 nm. Water was used as reference (Thaipong et al., 2006). The results were expressed as grams of gallic acid (GAE) per kg of fresh mass (FM).

Total flavonoid content (TFC) was determined by using 0.85 mL of juice mixed with 8.5 mL of 30% ethanol, 0.375 mL of NaNO2 (c = 0.5 mol.dm-3) and 0.375 mL of AlC1₃.6H₂0 (c = 0.3 mol.dm-3) as is described by Park et al. (2008). The mixture was measured at the wavelength of 506 nm by LIBRA S6 spectrophotometer (Biochrom, Cambridge, UK). Total flavonoid content was calculated from a calibration curve by using rutin as the standard. The results were expressed in mg.kg^-1 of FM.

The data were analysed using Excel 2013 (Microsoft Corporation, USA) and STATISTICA Cz version 12 (StatSoft, USA). Results were expressed by average ± standard deviation. Comparison of the results was per-formed using by Kruskal-Walllis test (α = 0.05). The samples of individual varieties were compared to each other. Furthermore, all samples of individual varieties of liturgical wines were compared against common wines.

In the study basic biologically active substances were determined in wine of these varieties – Pinot Noir, Red Traminer and Chardonnay. The basic measured results of the total antioxidant capacity, the content of polyphenols and flavonoids are given in Table 2.

The highest values of total antioxidant capacity were determined for variety Pinot Noir and these ones significantly exceed values of another observed varieties (up to 30x between sample RM1 a TR1). For variety Pinot Noir average values were measured over 2600 mg.L^-1 AAE for every sample, while for another two varieties Red Traminer and Chardonnay were found below 900 mg.L^-1 AAE. This finding confirms the fact, that antioxidant capacity is much higher for red wines than for white wines. This is due to the fact that in red wines substances with antioxidant capacity, for example phenolic substances, are in a significantly higher amount. In these more general facts results are in accordance with Rupasinghe and Clegg (2007) and Szajdek and Borowska (2008). Špakovská (2012) in her study presents the higher antioxidant activity in red wines than in white wines. Average values were measured for each sample for variety Pinot Noir.

Results, presented in Table 2, were used for a comparison between each sample for given wine variety. Results of the comparison of total antioxidant capacity are shown in Table 3. Even though between many compared samples the statistically significant difference (p <0.05) was found out for each variety, the difference between liturgical and common wines was not generally proven. For example, for variety Pinot Noir the statistically significant differences were calculated for all samples.

However, total antioxidant capacity in common and altar wine is in the same range of values (Table 2) so the statistically significant difference between these varieties of wine was not confirmed.

Similarly, to total antioxidant capacity, the values of polyphenolic substances are significantly higher than for other observed varieties. For varieties Pinot Noir the total phenolic content was above 6300 mg.L^-1 and for varieties Red Traminer and Chardonnay, average values of total phenolic content were set to 500 mg.L^-1. Statistical results of comparison for the total content of polyphenols are shown in Table 4. Again, the statistically significant difference (p <0.05) was found between many samples of each variety, but the difference between liturgical and common wines was not generally proven.

The phenolic substances are mainly contained in a grape peel. White wines are not macerated with peels in the production process, but peels are immediately removed and for this reason white wines contain fewer phenolic substances. In this aspect, the results are consistent with Rupasinghe and Clegg (2007) and Faitova et al. (2004). Špakovská (2012) presents the content of polyphenols in the range of 299 to 407 mg.L^-1 for white wines and for red wines in the range of 2130 to 650 mg.L^-1, which is consistent with our measured values.

Jančářová et al. (2013) states that the total polyphenol content is gradually decreasing with increasing time. Similarly, Andjelkovic, Radovanović and Radovanović (2013) also states, that the total polyphenol content grows during maturation and then decreases, ranging from 74.04 to 315.45 mg GAE.g^-1. The result of the above studies is finding, that the total polyphenol content varies with time.

Due to the method of agrotechnical processing of altar wines, which should have the sugar content 20 °NM and more, later harvesting is supposed. Harvest time may be affected by the amount of polyphenols, their content can be lower.

On the other hand, the content of fragrances can increase, and organoleptic properties can improve.

The last observed group of biologically active substances was group of flavonoids and their total content. Similarly, to the two previous observed parameters, values of total flavonoid content for variety Pinot Noir were significantly higher compared to other varieties.

For variety Pinot Noir the content of flavonoids ranged above 5200 mg.L^-1, but for varieties Red Traminer and Chardonnay values were measured below 1000 mg.L^-1. Comparison between each sample for observed varieties is given in Table 5. However, one can conclude here (to take account of total values), that the statistically significant difference between liturgical and altar wines cannot be established, but the difference between the individual samples can be established.

As stated by Rupasinghe and Clegg (2007), the nature and concentration of flavonoids in wine samples could influence both the wine variety and damaged grapes during harvest and the differences in processing methods. Sandler and Pinder (2003) states, that flavonoid content in red wines can exceed 1200 mg.L^-1. This reality is in line with our obtained results. In case of white wines, the content of flavonoids is up to several times lower due to their technological processing.