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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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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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