A study from Santiago, Chile finds that a 1 kGy gamma dose markedly lowered bacterial counts in minimally processed celery and cabbage without changing sensory quality over seven days.
Minimally processed celery and cabbage sold in a Santiago supermarket chain had high initial bacterial loads, with total plate and Enterobacteriaceae counts reaching 10(5) cfu/g, according to the paper published in Archivos Latinoamericanos de Nutrición. Neither E. coli nor Salmonella spp. were detected in any sample, irradiated or not. After irradiation at 1 kGy, celery showed a 4.7 log reduction in total plate count and 3.8 log reduction in Enterobacteriaceae; cabbage showed reductions of 3.8 and 3.6 logs respectively. During seven days of storage at 5°C, non-irradiated samples increased by 1.6 to 1.7 logs in both parameters, while irradiated samples stayed largely stable, except for a 1.2 log rise in celery total plate count.
The researchers determined D10 values for two E. coli strains (ATCC 8739 and a wild-type isolate) used as indicator organisms, then irradiated vegetable samples with five times that dose and tracked microbial counts and sensory quality over a week of refrigerated storage.
The paper's own data cover a single producer and one supermarket chain in Santiago, two vegetable types, and a seven-day storage window. Initial counts in most samples did not meet Chilean legislation specifications, a finding specific to this sourcing and handling chain and not generalised beyond it in the abstract.
For food safety practitioners and students, the result shows that a modest gamma dose can achieve several-log reductions in spoilage and indicator bacteria on fresh-cut vegetables, with sensory scores reported as statistically indistinguishable (p = 0.05) between irradiated and control samples across storage days. Whether this holds for other producers, vegetables, or packaging remains to be tested.
