MICROBIOLOGICAL SCREENING METHOD FOR INDICATION OF IRRADIATION OF SPICES AND HERBS - A BCR COLLABORATIVE STUDY

A BCR1 collaborative study was conducted with a microbiological screen ing method based on the combined use of the direct epifluorescent filt er technique (DEFT) and the conventional aerobic plate count method (A PC) for detection of irradiation of spices and herbs. Collaborative sa mples of whole allspice, whole and powdered black peppers, whole white pepper, paprika powder, cut basil, cut marjoram, and crushed cardamom irradiated with doses of 0, 5, and 10 kGy were analyzed by 8 laborato ries. The total number of the collaborative samples, with arbitrarily labeled codes, was 192. The percentage of acceptable results was 95.5% . The identification of irradiated from nonirradiated spices and herbs was analyzed statistically by using explorative techniques. The avera ge values of the differences between DEFT and APC in samples irradiate d with doses of 5 and 10 kGy were 5.1 and 6.1 logarithmic units, respe ctively. The differences between DEFT and APC generally increased to a t least 3.5 logarithmic units, whereas the difference in the case of u nirradiated spices was insignificant. However, conclusive evidence of irradiation relies on the knowledge that the sample was not fumigated or heat treated. The reproducibility relative standard deviations for the differences were 12.3,19.9, and 20.7% with the doses of 10 and 5 k Gy and for unirradiated samples, respectively, indicating acceptable v ariabilities among laboratories.