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Publications (55)
The effect of storage conditions on changes of pH, total soluble solids (°Brix), colour, betalains (betacyanins and betaxanthins), and 5-hydroxymethylfurfural was investigated in apple-beetroot juices stored at 2, 7 and 20 °C for 120 days. The results obtained showed that the quality of apple-beetroot juice is significantly influenced by temperatur...
Effect of screw-caps with oxygen scavenger bound inside the bore seal of the closure (screw-cap-O2S) was studied on dynamics of ascorbic acid (AA), 5-hydroxymethylfurfural (HMF), antioxidant activity expressed as Trolox equivalent (TEAC) and ascorbic acid equivalent (AAE), total polyphenols content (TPC) and colour changes in pineapple juices store...
Effects of different factors on the content of phenolics, anthocyanins, antioxidants and colour parameters in two varieties of Aronia and three varieties of Saskatoon berries were evaluated. The berries were extracted by dynamic solvent extraction using three different solvents (water, 50% ethanol (v/v) and dimethyl sulfoxide) and subsequently anal...
In the presented project the investigation on discrimination of geographic origin of wine in from border areas is carried out. Authentic wine samples from the border areas of Austria, Czech Republic, Slovakia (and from Serbia) are investigated and compared by applying different physico-chemical methods (e.g. IRMS, NMR, ICP-MS, ICP-OES, EPR, HPLC, U...
Investigation on discrimination of geographic origin in border areas is carried out by investigating and comparing authentic wine samples from the border areas of Austria, Czech Republic, Slovakia (and from Serbia) by applying different physico-chemical methods (e.g. IRMS, NMR, ICP-MS, ICP-OES, EPR, HPLC, UV-VIS, etc…). The comparison of the data s...
The effectiveness of three processing atmospheres to preserve the volatiles of orange juice with pulp during four-month shelf life was investigated over two years. Application of conventional “air” (O 2 ) and nitrogen (N 2 ) was evaluated in 2014, use of N 2 and carbon dioxide (CO 2 ) in 2015. Headspace-solid phase microextraction, gas chromatograp...
Evaluation of functional and bioactive compounds of Asparagus officinalis L. growing in conventional and organic greenhouse and conventional open – field farming was the aim of this research. Polyphenols in cladodes grown conventionally were higher than organic. Flavonoids and carotenoids were the highest in cladodes in open field. Organic spears w...
Complex analysis of the impact of post-production conditions on antioxidant status, content of selected polyphenols, color, and concentration of selected metals was evaluated in the group of ten most popular medical plants conventionally produced in the Czech Republic. Ultraviolet visible near infrared spectroscopy (UV–VIS–NIR), electron paramagnet...
Effect of time and temperature on ascorbic acid (AA), 5-hydroxymethylfurfural (HMF) and colour is described in grapefruit and carrot juices with pulp that were stored at (2 ± 1) °C, (7 ± 1) °C, and (20 ± 2) °C for 168 days. Degradation of AA followed the first-order kinetic model and showed some inverse correlations with HMF formation (r ≈ 0.6665–0...
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Organic, semiorganic, and conventional "Hayward" kiwifruits, treated with ethylene for 24 h and stored during 10 days, were assessed by UV spectrometry, fluorometry, and chemometrical analysis for changes in selected characteristics of quality (firmness, dry matter and soluble solid contents, pH, and acidity) and bioactivity (concentration of polyp...
Kiwi fruits “Hayward” were submitted to ethylene treatment during 24 h, following by storage at 20C for 10 days. Significant differences were found in polyphenols and in the antioxidant capacities in conventional, low chemical and organic kiwi fruits. Ethylene treatment increased the bioactivity of organic, low chemical and conventional kiwi fruit....
The volatile constituents of two chokeberry (Aronia melanocarpa) and five saskatoon berry (Amelanchier alnifolia) cultivars were evaluated by solid-phase microextraction (SPME) coupled to gas chromatography with flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS) during three seasons (2011–2013). Altogether, 39 and 3...
Conventionally (CG), semi-organically (low chemical, LCG) and organically grown (OG) kiwi fruit was stored at 0° C for 24 weeks. Firmness gradually decreased with storage time regardless of cultivation type, and the rate of softening was slightly higher in OG fruits than those of CG or LCG fruits. Soluble solids content increased with storage time,...
Proving of affiliation of wine sample to either organic or conventional production system and of its geographical origin although important both for consumer safety and food control authorities is still problematic. Characteristics of Slovak and some European wines obtained by spectroscopic methods including atomic absorption spectroscopy, electron...
Effect of storage on volatile aroma compounds of orange juice with pulp of Brazilian origin processed in Slovakia was investigated during 4 months of its expiration period. Headspace, solid phase microextraction (HS-SPME) and gas chromatography, mass spectrometry (GC-MS) detection was involved to isolate and analyse the composition of the volatile...
Antioxidant status, ascorbic acid concentration, 5-hydroxymethyl-2-furaldehyde (HMF) formation and total colour changes in a pineapple juice with the addition of small pieces of pineapple stored up to 26 weeks at 7 °C at different light conditions (darkness, day light) were characterized. Ascorbic acid losses reached after 26 weeks approximately 23...
Pectic polysaccharides have attracted great attention due to their health-promoting potential. From the Styrian oil-pumpkin biomass representing an alternative pectin source, two series of acidic polysaccharide fractions were isolated using in succession hot water, EDTA and dilute HCl. Chemical and spectroscopic (FTIR, NMR) analyses of the fraction...
Antioxidant activity, dry matter content, extractability, total phenolic compounds content and CIE L*a*b* colour characteristics of methanolic extracts of 10 spices exposed to γ-irradiation doses from 0 kGy (reference) to 30 kGy were evaluated in different time intervals after the irradiation by means of UV-VIS spectrophotometry in order to assess...
A new rapid, one-step semi-quantitative HPLC-MS method applicable for the separation and characterization of the group of total 10 BaP hydroxyderivatives (1-hydroxy benzo[a]pyrene, 2-hydroxybenzo[a]pyrene, 3-hydroxybenzo[a]pyrene, 4-hydroxybenzo [a]pyrene, 7-hydroxybenzo[a]pyrene, 8-hydroxybenzo[a]pyrene, 9-hydroxybenzo[a]py rene, 10-hydroxybenzo[a...
Pressurized hot water extraction (PHWE) was employed to prepare extracts from dried grape skin of two wine grape varieties (St. Laurent and Alibernet) at various temperatures (from 40 up to 120°C) and amounts of sample (0.5, 1.0 and 1.5 g). To assess the antioxidant activity of the extracts, electron paramagnetic resonance (EPR) spectroscopy was ap...
Vitamins are considered to be an essential non-caloric part of human nutrition. Meat and fish and also shellfish are one of the most important sources of vitamins. In this chapter, the classification of vitamins and vitamers as well as a short overview of their function is reviewed from the nutritional point of view. In addition, their role in meat...
A comprehensive characterization of grape skin methanolic and ethanolic extracts prepared by pressurized fluid extraction (PFE) at various temperatures within 40 to 120°C from two wine grape varieties, St. Laurent and Alibernet was performed. For the first time, an offline combination of PFE and electron paramagnetic resonance (EPR) spectroscopy to...
Besides the positive effects, γ-irradiation and heat treatment of foods usually lead to changes in their structure or composition, thus influencing their quality. In view of the fact that herbs and spices are important source of antioxidants in a human diet, any kind of treatment can have an impact on their antioxidant status, as well. In this cont...
Antioxidant properties of extracts prepared from native (non-irradiated) ground caraway (Carum carvi, L.) and bay leaves (Laurus nobilis, L.) samples, as well as from those γ-irradiated by Co60 source at doses from 5 to 30kGy were studied by EPR and UV–VIS spectroscopy, and expressed as Trolox Equivalent. Ferric reducing power, thiobarbituric acid...
Grape skins contain a plenty of different flavonoids, most of them revealing significant antioxidant proper-ties. In this contribution, a complex study is presented of grape skin ethanol extracts, prepared from grape skins of two vine grape varieties, Svatovavřinecké (St. Laurent) and Alibernet. Extracts were prepared from two different amounts of...
This work is focused on biodiesel production from tall oil and testing of selected biodiesel properties and their comparison with EN 14214. A method based on esterification straight by metanol and subsequent vacuum destillation of methylesters HFA (higher fatty acids) from mixture was chosen. The method seems to be more advantageous than that based...
The influence of γ-irradiation at doses from 5 kGy to 30 kGy on oregano (Origanum vulgare L.) was studied by the conventional microbiological analysis tests and by the combination of GC-FID; GC-MS; GC-Olfactometry (GC-O); EPR and UV-VIS spectroscopy. Microbiological analysis proved that γ-irradiation at 7.5 kGy was sufficient to achieve the microbi...
The effect of γ-irradiation on trichromatic color values L*, a*, and b* was determined in black pepper, oregano, and allspice samples irradiated at average doses from 5 kGy to 30 kGy. Trichromatic
values a* measured in methanol extracts of treated spices immediately after the irradiation process were significantly changed, but
the subsequent storag...
The influence of various gamma-radiation dose absorptions on oregano (Origanum vulgare L.) solid samples was monitored by means of electron paramagnetic resonance (EPR) spectroscopy. Further, the antioxidant activity of oregano methanol/water extracts was characterised using DPPH (1,1-diphenyl-2-picrylhydrazyl free radical); thiobarbituric acid rea...
The γ-radiation induced changes in ground black pepper (Piper nigrum L.), allspice berries (Pimenta officinalis L.), ginger root (Zingiber officinale Rosc.), dried clove buds (Caryophyllus aromaticus L.) and dry oregano leaves (Origanum vulgare L.) exposed to doses from 2.5 to 30 kGy using 60Co source were studied by EPR spectroscopy. Influence of...
Antioxidant activity and EPR investigations of irradiated ground black pepper (Piper nigrum L.) were evaluated. The black pepper was exposed to γ-irradiation at doses from 5 to 30 kGy. The effect of irradiation on antioxidant properties of black pepper extracts was investigated by radical-scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) ra...
Wines are increasingly considered to be beneficial to health, so we expanded our previous investigations of red and white wines to Tokay wines, employing electron paramagnetic resonance spectroscopy (EPR). Four sources of free radicals were used in scavenging experiments: thermally decomposed radical initiators, K2S2O8 and 2,2′-azo-bis(2-methylprop...
Paper and other lignocellulosic materials undergo the destruction as a result of ageing, influenced by various factors and accelerated by the formation of acids from components, used during its production [S. Katuščák, Wood Res. 45 (2000) 1; S. Katuščák, L. Ďurišová, Wood Res. 118 (1988) 75]. Various deacidification processes were developed in an o...
The γ-radiation treatment of ground black pepper samples resulted in the production of three paramagnetic species (GI–GIII) which arise from a different origin and have different thermal behavior and stability. The axially symmetric spectra can be characterized by the spin Hamiltonian parameters: GI (g⊥=2.0060, g∥=2.0032; , ) and GII (g⊥=2.0060, g∥...
The non-invasive method of determination of lignin content based on measurements of reflectance at 280 nm was evaluated. The application of this method for estimation of the initial content of lignin in degraded samples is problematic due to uncertainty introduced by the degradation processes. The use of the spectroscopic method for non-destructive...
The antioxidant status of foods and plant products is nowadays widely characterized by means of various analytical and spectroscopic methods. In the present work, the thermal stability of lager beers and the influence of ascorbic acid addition on their stability, as well as the antioxidant properties of commercial teas and wines have been studied b...
Radical-scavenging activity of the water-soluble derivative obtained from cell wall of the baker's yeast Saccharomyces cerevisiae was investigated using the technique of electron paramagnetic resonance. The experiments involved a study of the scavenging activity of carboxymethyl (1→3)-β-d-glucan (CMG) towards the radicals formed in the thermally in...
Free radical scavenging and antioxidant activities of metabolites produced by carotenogenic yeasts of Rhodotorula sp. and Sporobolomyces sp. grown under heavy metal presence were studied using various EPR experiments. The thermally initiated decomposition of K(2)S(2)O(8) coupled with EPR spin trapping was shown to be the best choice to characterize...
The cone calorimetric ageing of paper samples is the appropriate equivalent to standardly used ageing methods. The DRIFT spectroscopy is suitable and reliable method for the evaluation of changes, occuring in paper sample structure during the ageing process. The results are in good accordance with the test of mechanical properties. Additional exper...
The quality of the processes of stabilization of paper and other lignocellulosics using deacidification and strengthening has been evaluated mostly by measuring kinetic relationships between physico-mechanical properties and ageing time. The evaluation, comparison and optimizing of the modification processes can be promoted through improving knowle...
The antioxidant properties of green, black and mixed (fruit) tea samples of different origin were investigated by means of EPR spectroscopy. A six line EPR spectrum of solid tea samples indicates the presence of Mn(II) ions and it is superimposed with a sharp singlet line attributed to semiquinone radical species (Delta H(pp)=1 mT; g=2.0022). Antio...
In thermally-accelerated aging followed by EPR spectroscopy of beer samples of various stabilities, free radical 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPOL) was shown to be an effective indicator of the breakdown of a sample's stability, comparable to the commonly used spin trapping agent alpha-phenyl-N-tert-butylnitrone (PBN). Both ind...
Projects
Projects (2)
In the presented project the investigation on discrimination of geographic origin of wine in from border areas is carried out. Authentic wine samples from the border areas of Austria, Czech Republic, Slovakia (and from Serbia) are investigated and compared by applying different physico-chemical methods (e.g. IRMS, NMR, ICP-MS, ICP-OES, EPR, HPLC, UV-VIS, etc…). The comparison of the data sets from the participating countries and the different applied methods will show, to which extent a differentiation can still be achieved in the border areas of the respective countries, which methods prove most efficient and sensitive and if a combination of methods will lead to an increased sensitivity.
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