Flavour of irradiated herbs
1994
Venskutonis, P.R. (Kaunas Univ. of Technology (Lithuania). Dept. of Food Technology)
The inflluence of drying, gamma and beta irradiation, and storage time on the composition of thyme (Thymus vulgaris L.) and basil (Ocimum basilicum L.) flavour was examined in the present study. Dried thyme and basil herbs were exposed to gamma and beta irradiation at doses of 3, 10 and 30 kGY, flavour constituents were isolated by simultaneous distillation-extraction technique in the Likens-Nickerson apparatus and analyzed by capillary gas chromatography. In thyme and basil 72 and 67 compounds, respectively, were identified and determined quantitatively. Thymol (40-48 per cent), p-cymene (21-26 per cent), gamma-terpinene (3-8 per cent), and carvacrol (5-8 per cent) were the main constituents in thyme; estragole (87-89 per cent) eucalyptol, linalool, methyl eugenol and beta-caryophyllene (1-2.5 per cent) were present in basil. The reduction in the amount of some monoterpenes during drying of thyme was almost equal for oven and freeze drying method. During storage the changes in the concentration of some flavour compounds were found to be quite significant (e.g. the reduction of myrcene and gamma-terpinene in thyme and estragole in basil). However, the influence of irradiation on the composition of flavour volatiles was rather insignificant. Some reduction in the concentration of phenolic compounds in basil (estragole, methyl eugenol) were determined after irradiation. Also, after 5 and 10 months of storage there were slight differences in the concentration of some constituents between irradiated and untreated samples.
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