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The effects of cAMP-elevating compounds IBMX (3-isobutyl-1-methyl­xanthine) and isoproterenol, and that of rutin (an effective superoxide scavenger) were studied on orthovanadate- (a putative protein-phosphotyrosine phosphatase inhibitor) induced nitric oxide (NO) production in J774A.1 mouse macrophage cells. As we previously reported (Koncz and Horváth, 2000), rutin and sodium orthovanadate act synergistically to induce production of high amount of NO in J774A.1 cells. IBMX, an agent that can elevate cAMP level in the cells, can reduce the production of both the LPS- and rutin + orthovanadate-induced NO in macrophages. In contrast, isoproterenol, a non-selective ß-adrenergic receptor agonist, that reduced the LPS-induced NO production in macrophage cells, was unable to reduce the rutin + orthovanadate-induced NO production without negatively affecting cell viability. Moreover, isoproterenol dramatically enhanced the orthovanadate-induced NO synthesis in J774A.1 cells. Our previous study clarified that rutin and orthovanadate, in a specific concentration ratio of both, were able to produce hydrogen peroxide (H2O2). Using 2',7'-dichlorofluorescein-diacetate as a marker for H2O2, isoproterenol alone induced its oxidation but the rutin plus orthovanadate-induced H2O2 production was reduced by isoproterenol. These observations have revealed that, in some cases, H2O2 and superoxide (O2 -) scavengers can act in a reverse mode on macrophage cells depending on the presence or absence of orthovanadate.

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Ochratoxin A is a mycotoxin produced by Aspergillus and Penicillium species. This mycotoxin is a common contaminant of various foods including cereal products, spices, dried fruits, coffee, beer and wine. Besides cereal products, goods of grape origin contribute significantly to ochratoxin exposure of humans. The ochratoxin content and mycobiota of raisins purchased in Hungarian outlets were examined in this study. Ochratoxin A content was examined by an immunochemical technique, and the results were confirmed by HPLC analysis using fluorescent detection. Altogether 20 raisin samples were analyzed. Ochratoxin A was detected in all but two samples with ochratoxin concentrations ranging from 0 to 6.2 mg kg-1. The most heavily contaminated raisin sample came from Iran. However, none of the raisins contained ochratoxin A above 10 mg kg-1, the European Community maximum allowable limit in raisins. The mycobiota of raisin samples was also examined to clarify which species could be responsible for ochratoxin A contamination. All except three raisin samples were contaminated with black aspergilli, some of which produced ochratoxin A. Besides A. carbonarius, ochratoxin producing A. tubingensis isolates dominated in the samples.

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Basket willow (Salix viminalis L.) was grown in open-field experiment. The brown forest soil (sand texture, pHKCl 7.7, humus 1.6%, CEC 11.5 cmolc/kg; Cd-0.11, Cu-7.1, Pb-8.1, Zn-25.0 mg/kg in aqua regia extract) was treated with municipal sewage sludge compost (MSSC) (25 t/ha wet weight, 12.8 t/ha dry weight in 2009; 50 and 100 t/ha wet weight, 25.4 t/ha and 50.8 t/ha dry weight in 2008). The MSSC was moderately contaminated with toxic metals (Cd-<0.5, Cu-140, Pb-19, Zn-440 mg/kg in aqua regia extract in 2008, and Cd-<0.5, Cu-299, Pb-69, Zn-865 mg/kg in aqua regia extract in 2009). Accumulation of Zn in treated willow leaves doubled 4 months after 25 t/ha MSSC application, while in treated twig tips 30% less Zn was found than in control. Zn (max. 133 mg/kg d.w.), Cd (max. 1.15 mg/kg d.w.) and Cu (max. 7.73 mg/kg d.w.) accumulations in leaves or twig tips of basket willow were 16 months after 50 or 100 t/ha MSSC application. Twenty months after MSSC application in the harvested twigs (shoots without leaves) of 50 or 100 t/ha MSSC-treated cultures the Zn concentrations were only 9.8–14.3% higher than in controls. We suppose that there is not a direct danger of considerable Zn accumulation in the bioash after incineration of MSSC-treated willow shoots in biomass power plants.

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Potato and beetroot were grown on soils previously treated with heavy metal salts. Each particular microelement had a high concentration in both potato and beetroot [cadmium (Cd) 3.7 and 55.4, lead (Pb) 8.1 and 3.0, and mercury (Hg) 5.8 and 6.8 mg/kg dry matter, respectively]. In a metabolic balance trial 16 New Zealand White rabbits were fed 50 grams of basal diet and potato or beetroot ad libitum. The apparent digestibility of major nutrients and the accumulation of the microelements in different organs were investigated. Both potato and beetroot samples of high Pb and Hg content had the significantly (p < 0.05) lowest digestibility of organic matter and nitrogen-free extract. The Cd ingested from both potato and beetroot accumulated in the kidneys and liver (2.85 and 1.48 as well as 0.459 and 0.265 mg/kg, respectively). All the microelements (Cd, Pb and Hg) accumulated in the testicles (0.196, 0.32 and 0.199 mg/kg, respectively), reducing the rate of spermatogenesis. The tissue retention ofheavy metals depends not only on the element itself, but also upon the ‘carrier’ feedstuff.

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Acta Alimentaria
Authors:
Á. Koncz
,
L. Mészáros
,
J. Farkas
,
K. Pásztor-Huszár
,
R. Helt
, and
N. Lechner

Thermal and HHP treatments were compared. We established that the applied HHP treatments reduced the total cell count more significantly than thermal treatments. For example, the 10 min 600 MPa/10 min HHP treatment was equivalent to about 10 min thermal treatment at 70 °C. This combination of temperature and time is not used in the pasteurisation practice of the dairy industry. The various thermal treatments reduce the phosphatase enzyme activity to between one-third and one-hundredth of the original activity. The HHP treatments yielded similar results. Six hundred MPa pressure caused 10 to 70% decrease in the enzyme activity, while 700 MPa pressure led to a decrease of one log cycle.In the second year we tried to investigate the kinetics of the effect of HHP treatment. The 5, 10, 20, 40 min holding times were systematically applied in the range of 400 to 700 MPa. According to the results, 600 and 700 MPa HHP treatments effectively assured a decrease in the total cell count and the alkaline phosphatase enzyme activity. No organoleptic changes occurred.

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Reliable product characteristics are needed for the prediction of shelf life by mathematical models in the post-harvest sector. Exact knowledge of the nature of changes during ripening and storage in refrigerated storage is essential. Authors investigated physical, chemical and biological changes of field-grown, autumn-harvested food grade potato (cultivar Kondor) as a function of temperature and storage time and the market quality was determined by visual assessment. Most of the investigations were preceded by sampling and methodological examinations. The most appropriate characteristics for the predictive modelling were: water soluble solids content, total starch content, weight loss during storage, marketability of the product (visually assessed) and texture parameters: acoustic firmness factor and bio-yield (by Instron Universal Testing Machine). Components of complex impedance, except for some cases, would be unreliable factors in model creation.

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Acta Alimentaria
Authors:
J. Varga
,
Z. Koncz
,
S. Kocsubé
,
T. Mátrai
,
J. Téren
,
V. Ostry
,
J. Skarkova
,
J. Ruprich
,
A. Kubatova
, and
Z. Kozakiewicz

Ochratoxin A is a mycotoxin produced by Aspergillus and Penicillium species. This mycotoxin is a common contaminant of various foods including cereal products, spices, dried vine fruits, coffee, cocoa, beer and wine. Apart from cereal products, beer and wine contribute significantly to ochratoxin exposure of humans. In the Mediterranean region of Europe, the black Aspergillus species are the sources of ochratoxin contamination of grape products. In this study, we examined the source of ochratoxin contamination of grapes in Hungary and the Czech Republic. The mycobiota of grape berries from 25 Hungarian and Czech vineyards was examined. Potential ochratoxin producing fungi were only identified in grapes from Southern Hungary. Among the 16 black Aspergillus strains isolated, 12 belong to the A. niger species, and 10 produced small amounts (1.5–10 μg kg −1 ) of ochratoxin A in a liquid medium. We could also identify an A. tubingensis isolate which produced 3.5 μg kg −1 ochratoxin A in a liquid medium at pH 6.0. However, the amount of ochratoxin A produced was very low even in a medium which is favourable for mycotoxin production, and ochratoxin A was not detected in any of the grape juice, must and wine samples examined, indicating the absence of health hazard to costumers. Other potentially toxigenic fungi including Aspergillus flavus, Penicillium expansum and Alternaria species were also isolated. Further studies are in progress to evaluate the importance of these fungi in food safety.

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