In twe1ve bottles of Traminer (vintage 2000, late harvest, vine growing area Žernoseky), total content of polyphenols (TPC) and resveratrol (which are ascribed to have a positive impact on human body) were measured to determine the variability of the content of measured substances in various bottles of the same batch and from the same manufactuter. TPC was measured spectrophotometrically using Folin-Ciocalteau's reagent with He)"ios 1 spectrophotometer at wavelength L ='765 nm. The content of resveratrol was measured using HpLC method with isocratic elution on the chromatograph WatersTM at wavelength l" = 3 13 nm. TPC ranged from 251 "7 Ío 282.5 mg.1_1 (average content 212.6 mg.I_I) and the content of resveratrol ranged from 0.050.0g mg.l-l (the average content 0.06 mg.1-1). From the results obtained it is possible to conclude that even in the samples with the same maturation conditions, bottling and storage, a certain role has also the choice of the bottle.

The effect of an abiotic stress caused by cadmium on the total flavonoid content in roots, shoots and leaf blades of spring barley variety Kompakt grown in a climate-control room for 28 days was investigated. Total flavonoid con tent (F) was determined spectrophotometrically with sodium nitrite, Cd content by atomic absorption spectrometry. Treatment of barley plants with Cd (1.10 –6 mol/l) in nutrition solution caused the decrease of F in the all parts of the

Wire is a significant source of antioxidants in human nutrition. Every glass of wine contains approximately 200 different phenolic compounds, several of which have been noted as antioxidants because they have been shown to slow down the potentially damaging cell oxidation process. In white Riesling from different wine-growing sub-regions, kinds of wine, years of harvest and vintners, the content of total polyphenols (TP) was determined using spectrophotometric method, and that of trans-resveratrol (R) by HPLC method. The TP content was presented as gallic acid equivalent per litre of wine, and the content of R as trans-resveratrol per litre of wine. TP values in the wine-growing region of Bohemia ranged from 223.0 to 532.7 mg/l (average content 330.3 mg/l), in the wine-growing region of Moravia from 175.0 to 465.0 mg/l (average content 271.7 mg/l), while R values in the wine-growing region of Bohemia ranged from < 0.033 to 0.421 mg/l (average content 0.117 mg/l), in the wine-growing region of Moravia from < 0.033 to 0.875 mg/l (average content 0.123 mg/l). The highest average TP content (370.1 mg/l) and R content (0.262 mg/l) were found in the sub-region Roudnicka (the wine-growing region of Bohemia). The harvest year of 1994 was evaluated as that providing the highest average levels of TP (386.5 mg/l) and R (0.201 mg/l). The kind of wine with the highest average TP was the kind of "selected grapes" (327.2 mg/l), while the highest average R content was found in the late harvest wine (0.141 mg/l). The R and TP contents were not significantly affected by vintage, wine-growing sub-region or the kind of wine. The statistically significant correlation between TP and R content was not demonstrated (5.73%).

Yacon [Smallanthus sonchifolius (Poepp. et Endl.) H. Robinson], a native plant of the Andes, belongs to the family Compositae (Asteraceae). It represents a traditional crop from the original population of Peru. Most of the tuberous root biomass is constituted by water (> 70% of the fresh weight). Saccharides, especially oligofructans, form 70-80% of their dry weight. Four yacon ecotypes originating from Bolivia, Ecuador, Germany and New Zealand were cultivated on the trial fields of the Czech University of Agriculture in Prague in 1995, 1996, 2000 and 2001. Considerable differences among the ecotypes were observed in their content of inulin (141-289 mg/kg d.m.) and lesser for fructose levels (195-217 mg/kg d.m.). No differences were found in glucose and saccharose contents. The highest inulin and fructose contents were found in the harvests from 2001 and 2000, similar trends were found for glucose. Statistically significant effect on the content of all saccharides has the year of cultivation. Tubers contained much higher levels of inulin (179 g/kg d.m.) and fructose (193 g/kg d.m.) in comparison with rhizomes. No significant differences were found for saccharose (higher in rhizomes) and glucose (lower in rhizomes). The contents of inulin and fructose in the upper and lower parts of tubers were reciprocal. During the storage period of 140 days at 10degreesC and 75% a relative humidity inulin content decreased by 48.7% and monosaccharides content increased (fructose by 9.97%, glucose by 31.4%) due to hydrolysis. Likewise saccharose content increased by 12.9%.

The effect of abiotic stress caused by cadmium on the total polyphenols content in root, shoots and leaf blades of barley was investigated in model experiments. Total polyphenols content was determined spectrophotometrically with Folin Ciocalteau's reagent, Cd content by atomic absorption spectrometry (AAS) in 28-day-old plants. Treatment of the barley plants with Cd (1.10-6 mol/l) in a nutrition solution caused the increase in the total polyphenols in all parts of the plant. The highest increase was found in the leaf blades (35.2%, 8340 mg/kg d.m.), a lesser increase found in the shoots (16.7%, 3590 mg/kg d.m.), and the lowest increase found in the roots (10.3%, 3650 mg/kg d.m.). The highest Cd increase in the treated plants was found in the roots (10 400%, 240 mg/kg d.m.), the lesser in their shoots (4990%, 16.3 mg/kg d.m.), and the lowest in the leaf blades (2580%, 5.78 mg/kg d.m.). There was found a statistically significant increase (at least P < 0.05) in the total polyphenols and Cd contents in all investigated parts of the plant. Statistically significant differences (at least P < 0.05) of the total polyphenols and Cd contents among barley roots, shoots, and leaf blades were found.

The influence of accelerated ageing test (AAT), i.e. of higher temperature and humidity, on the content and composition of phenolic compounds in the grains of five cultivars of wheat (Triticum aestivum L.) was studied in the years 1998 and 1999. Total polyphenols were determined spectrophotometrically by Folin-Ciocalteau's phenolic reagent and free phenolic acids by an HPLC method in control samples and after deterioration treatment (AAT) in the Ebi, Estica, Nela, Samanta and Šárka cultivars. Statistical significance of deterioration treatment, cultivar, cultivation site, and harvest year was proved. Content of total polyphenols increased during deterioration and levels of the individual free phenolic acid changed depending on their structures. Mean contents of total polyphenols varied from 600 to 960 mg/kg of dry matter. The increase caused by the AAT ranged between 0-20%, the greatest mean increase was observed in the cultivar Nela (by 19%). Sinapic acid (as high as 540 mg/kg of dry matter), 3-hydroxy-benzoic acid and 7-hydroxycoumarin were determined as the major phenolic acids and coumarins. A decrease of free phenolic acids containing methoxy groups in their molecules (sinapic and vanillic acids) and an increase of phenolic acids with free hydroxy groups (caffeic and gallic acids) was observed after deterioration treatment. Statistically significant (P ≤ 0.05) effect of AAT on the content of free phenolic acids was observed.

The effects were tested of white fleece on the contents of ascorbic acid, nitrates, and polyphenols in 1999 and 2000, and on the carotenoids content in 2000 and 2001 in tubers of two early potato varieties (Adora and Impala) in field trials on two cultivation sites (Prerov n/Labem and Prague-Troja). Early irrigated potatoes were cultivated according to the uniform methodology for field trials. Two variants were compared - cultivated plants covered with white fleece (Pegas-Agro UV 17) and the controls without any covering. The tubers were harvested three times in intervals of 7-16 days. The results were statistically tested by ANOVA and Tukey's methods. Ascorbic acid content showed a tendency to higher values in the potatoes covered with white fleece as compared with the control samples (average increase by 12.3%). The effect of the fleece was significantly affected by the potato genotype and the year of cultivation (cv. Adora showed a content higher by 12.54% in comparison with the control). The tendency to reduce nitrate levels was observed in potato tubers cultivated under the fleece, especially in the second term of harvest (on average by 14.34%). The decrease between the first and the third term of harvest was apparent. The higher was the maturity of potato tubers, the lower nitrate content was found. Significant differences were found between the varieties (P = 0.0058) and the cultivation sites (P = 0.0399). The effect of white fleece on polyphenol content was not statistically significant. However, the effect of the year of cultivation on the polyphenols content was significant (P = 0.0094). The effect of white fleece on the carotenoids content was not statistically significant but a tendency to lower contents in the variant with white fleece was found (by 7.2%). The sites and the varieties affected the carotenoids contents significantly (P = 0.0028 and P = 0.0417, respectively).

Polyphenolic antioxidant compounds were studied in three onion varieties (red - cv. Karmen, yellow - cv. Vsetana and white - cv. Ala) regarding their total content and qualitative composition of flavonoid complex. The effects of temperature and storage period during onion storage were also studied. The total content of polyphenols was estimated spectrophotometrically with Folin-Ciocalteau's phenolic reagent and individual flavonoid components by HPLC method using Waters TM chromatograph on Watrex 250 × 4 mm Sepharon SGX C18 7μm column with gradient elution. The highest amount of polyphenolic compounds was found in red variety Karmen (108,300 mg/kg DM), the lowest amount in white variety Ala (26,445 mg/kg DM) while the yellow variety Vsetana had average content of total polyphenolic compounds 65,210 mg/kg DM. An increase in total polyphenols during storage was found in red and yellow varieties, esp. during storage at a laboratory temperature (22°C). Among the flavonoid and polyphenolic compounds as major constituents spiraeoside (quercetin-4´-O-β-D-glucoside), rutin and quercetin and three other not identified compounds were found. Significant varietal differences were found. The compound with the highest content was spiraeoside (32,234 mg/kg DM in red cv. Karmen, 23,283 mg/kg DM in yellow cv. Vsetana and 265 mg/kg DM in white cv. Ala). Rutin ranged from 15 mg/kg DM in cv. Ala to 157 mg/kg DM in cv. Karmen and similarly quercetin from 1 mg/kg DM in cv. Ala to 163 mg/kg DM in cv. Karmen. During storage an increase in flavonoids could be observed, esp. at a laboratory temperature compared to storage at a lower temperature.