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47 2008

Journal of Food and Nutrition Research
Súhrny čísla 2 / 2008

SÁDECKÁ, J. – POLOVKA, M.
Multi-experimental study of γ-radiation impact on oregano (Origanum vulgare L.)
Journal of Food and Nutrition Research, 47, 2008, č. 2, s. 85-91

Martin Polovka, Department of Chemistry and Food Analysis, VÚP Food Research Institute, Priemyselná 4, P. O. Box 25, SK – 824 75 Bratislava, Slovakia. Tel.: 00421 2 50237 174, fax: 00421 2 55571 417, e-mail: polovka@vup.sk

Súhrn: 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 y-irradiation at 7.5 kGy was sufficient to achieve the microbiological decontamination of oregano samples, persisting even after 8 months of storage. The study of γ-irradiation impact on essential oils’ composition and on organoleptic quality changes, evaluated using GC-FID, GC MS, and GC-O involving the Aroma Extract Dilution Analysis (AEDA) method revealed no changes in the chemical composition and non-considerable changes in the content of volatile oils’ compounds at samples γ-irradiated up to 10 kGy. Only non-significant changes of flavours upon the radiation treatment even at dose of 30 kGy were noticed. The analysis of EPR spectra confirmed the presence of two signals in a reference sample, attributed to Mn2+ ions and to stable semiquinone radicals. In addition, the dose-dependent formation of radicals of different origin (mostly cellulose and carbohydrate) showing the diverse thermal stability and life-time was noticed in g-irradiated samples. UV-VIS experiments confirmed that the antioxidant activity of oregano ethanolic extracts was only slightly affected by the absorption of γ-radiation.

Kľúčové slová: oregano; γ-irradiation; microbiological contamination; organoleptic quality; chemical composition; sensorial analysis

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