Mojmír Baroň

The influence of guar gum on textural and sensory properties of rolls made from semi-finished frozen products.

Textural and sensory properties of rolls produced from semi-finished frozen products with additions of guar gum were assessed. A commercial wheat flour T 512, ingredients such as yeast Saccharomyces cerevisiae, rapeseed oil, sodium chloride were used for preparing dough and final products. Guar gum and commercial additive Trial RC2 were used as additives for production. The textural properties of rolls were measured by a TA-XT Plus Texture Analyzer. All samples were evaluated by selected assessors. A five-point hedonic scale was used for evaluation characteristics such as taste, pliancy, texture, porosity, stickiness, gumminess, crispness and quality. The obtained data showed nonsignificant difference in moisture of rolls after baking and 3 days after baking. Control sample of rolls had higher firmness in comparison to other samples with guar gum after baking. Samples of rolls with higher addition of guar gum (10 g.kg -1 and 15 g.kg -1 ) had less firmness in comparison to control sample and sample with 5 g.kg -1 of guar gum. Sensory analysis showed negligible differences among all samples in monitored characteristics. Sensory assessors evaluated all samples as identical. Increased addition of guar gum in rolls led to the extension of shelf life (lower firmness) at unchanged sensory properties of the rolls.

Assesment of the antioxidant activity and content of polyphenolic compounds in grapevine seeds

Our work was focused on the study of the antioxidant properties of grapevine seeds. We monitored the grapevine seeds of 6 cultivars of Vitis vinifera , L. (Nativa, Kofranka, Blaufrankish, Marlen, Cabernet Moravia and Italian Riesling). Antioxidant activity was determined by three principally different methods (DPPH, ABTS and FRAP), the content of the total polyphenolic compounds was determined by the Folin ciocalteu method, and the content of the total flavanols was determined by DMACA reagent (p-dimethylaminocinnamaldehyde). Results are presented as an equivalent of gallic acid in g.L -1 , respectively were expressed as g.L -1 of catechin equivalents (DMACA method). The highest values of antioxidant activity were measured in the cultivar Nativa (DPPH - 7.75 g.L -1 , ABTS - 4.888 g.L -1 , FRAP - 4.25 g.L -1 ). Conversely, the lowest values of antioxidant activity were detected in the cultivar Kofranka (DPPH - 7.08 g.L -1 , ABTS - 4.17 g.L -1 , FRAP - 4.55 g.L -1 ). Cultivar Nativa also reached the highest content of flavonols (3.77 g.L -1 ). The highest measured values of the content of total polyphenolic compounds were identified in the cultivar Cabernet Moravia (15.2 g.L -1 of GAE). Conversely, the lowest values of the content of total polyphenolic compounds were detected in the cultivar Nativa (8.04 g.L -1 ). Pearson correlation coefficients were calculated for the existing values between antioxidant activity (DPPH, ABTS, FRAP), contents of flavonols, and contents of total polyphenols. The highest correlation coefficient was found between the DPPH and ABTS methods; specifically, it was 0.857.

The study of antioxidants in grapevine seeds

Grapevine seeds contain a large amount of antioxidant components, and are therefore recommended in the prevention and treatment of many diseases. For this research, we studied the antioxidant properties of grapevine seeds from the Marlen variety, as evidence suggests that these types have higher resistance against fungal diseases. Through high-performance liquid chromatography with UV/VIS detection, a total of 10 antioxidant components were selected for further investigation, specifically: catechin, epicatechin, rutin, quercitrin, quercetin, caftaric acid, caffeic acid, p-coumaric acid, ferulic acid, and gallic acid. The antioxidant activity was determinated spectrophotometrically through the adoption of three fundamentally different methods (the DPPH assay, the ABTS method, and the FRAP method). Using the Folin-Ciocalteu method, it was possible to determine the content of all the polyphenolic compounds. The results of the assessment antioxidant activity and the content of polyphenolic compounds were recalculated to gallic acid equivalents (GAE). The values of the antioxidant activity as determinated by the DPPH test were 6643 (±154) mg of GAE; 1984 (±88) mg of GAE when using the FRAP method; and 812 (±31) mg of GAE when the ABTS method was utilised. The content of the total polyphenolic compounds came to 6982 (±221) mg of GAE. The most abundant antioxidant was catechin, with a content of 115 mg.L -1 , whilst the least represented compound was ferulic acid (0.139 mg.L -1 ). Overall, this study showed a high antioxidant potential of grapevine seeds.

Srovnání rosé vín dle obsahu vybraných fenolických látek a antiradikálové aktivity.

Rosé vína si v posledních letech vydobyla pozornost a těší se velké oblibě nejen v ČR, ale i jinde ve světě. V ČR se vyrábějí nejčastěji z tradičních odrůd jako je ‘Rulandské modré’, ‘Frankovka’, ‘Zweigeltrebe’, ‘André’ a ‘Cabernet Sauvignon’. Nyní se však objevují rosé vína vyrobená z nověji registrovaných odrůd jako ‘Cabernet Moravia’ či ‘Merlot’. Zcela novým počinem jsou rosé vína vyrobená z českých interspecifických modrých moštových odrůd, jako ‘Cerason’ nebo ‘Laurot’. Tyto odrůdy mají zvýšenou odolnost proti houbovým chorobám, často obsahují v bobulích více barviv, ale i dalších látek fenolické povahy, tedy flavanolů, katechinů a stilbenů. Řada obsažených látek vykazuje antiradikálovou aktivitu a tím i zdravotní prospěšnost. Vína z těchto odrůd mají obvykle vyšší barvu, bývají svěží a intenzivně ovocná. Srovnání rosé vín dle obsahu vybraných fenolických látek a antiradikálové aktivity