EFFECT OF IRRADIATION ON THE MICROBIOLOGICAL STATUS AND FLAVORING MATERIALS OF SELECTED SPICES

Spices from Egyptian local markets were irradiated with different reco mmended doses (0, 5, 10, 20 and 30 kGy). The spices tested included dr ied leaves of marjoram (Majorana hortensis Moench), rhizomes of ginger (Zingiber officinale Roscoe) and powdered hot pepper (Capsicum annum L.). The study included the isolation and identification of micro-orga nisms in spices following their irradiation, as well as gas chromatogr aphic (GLC) chemical analysis for the presence and structure of volati le oils, pungent and pigment materials. The results showed that hot pe pper was contaminated more (9.2 x 10(5)/g) than marjoram (4.2 x 10(3)/ g) and ginger (14.3 x 10(3)/g) with respect to total aerobic bacterial content. The total contents of moulds were 4.8 x 10(3)/g, 5.7 x 10(3) /g and 19 x 10(3)/g in the same spices, respectively, but the pathogen ic moulds and bacterial strains differed according to the type of spic e. Irradiation at 10, 20 and 30 kGy caused complete elimination of mic ro-organisms, whereas 5 kGy was less effective. With the GLC method ch osen 18 and 50 compounds could be detected in the extracts of marjoram and ginger, respectively; gamma-terpinen and zingiberen being the maj or compounds in marjoram and ginger, respectively. A noticeable reduct ion was observed in the amount of terpenes present in irradiated marjo ram; they were converted to monoterpenesalcohols. Ginger was more sens itive to irradiation, especially at high doses, but moderate changes w ere detected at low doses (5 and 10 kGy). A slight, but significant ef fect on the capsaicin (pungent compound) in hot pepper was observed fo llowing irradiation, whereas no changes in total pigments resulted at any dose. These results prove that 10 kGy is a sufficiently high dose to eliminate the microorganisms in spices, causing only slight changes in the flavouring materials.