Effect of X-ray treatments on Escherichia coli O157:H7, Listeria monocytogenes, Shigella flexneri, Salmonella enterica and inherent microbiota on whole mangoes.
Mahmoud B. S. M., Nannapaneni R., Chang S., Coker R.
Author Affiliation: Coastal Research & Extension Center, Mississippi State University, 3411 Frederic St., Pascagoula, MS 39567, USA.
Letters in Applied Microbiology 62 : 138-144
Abstract : The aims of this investigation were to; (i) study the effect of X-ray treatments in reducing Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica and Shigella flexneri on whole mangoes, and (ii) study the effect of X-ray treatments on microflora counts (mesophilic counts, psychrotrophic counts and yeast and mould counts) of whole mangoes during storage at ambient temperature (22°C) for 30 days. A mixture of three strains of each test organism was spot inoculated (100 µl; approx. 8-9 log CFU ml-1), separately, onto the surface (5 cm2) of whole mangoes, air-dried (30 min), and then treated with different doses of X-ray (0, 0.1, 0.5, 1.0, and 1.5 kGy). Approximately 2.9, 1.8, 2.1 and 5.2 log CFU cm-2 reduction of E. coli O157:H7, L. monocytogenes, Sh. flexneri and Salm. enterica were achieved by treatment with 0.5 kGy X-ray respectively. Furthermore, the populations of E. coli O157:H7, L. monocytogenes, Sh. flexneri and Salm. enterica were reduced to less than the detectable limit (2.0 log CFU cm-2) by treatment with 1.5 kGy X-ray. Treatment with 1.5 kGy X-ray significantly reduced the initial inherent microflora on skin of whole mangoes and inherent levels were significantly (P0.05) lower than the control sample throughout storage at 22°C for 30 days.