Effect of X-ray treatments on Escherichia coli O157:H7, Listeria monocytogenes, Shigella flexneri, Salmonella enterica and inherent microbiota on whole mangoes

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 degrees C) for 30days. A mixture of three strains of each test organism was spot inoculated (100l; approx. 8-9logCFUml(-1)), separately, onto the surface (5cm(2)) of whole mangoes, air-dried (30min), and then treated with different doses of X-ray (0, 01, 05, 10, and 15kGy). Approximately 29, 18, 21 and 52logCFUcm(-2) reduction of E.coli O157:H7, L.monocytogenes, Sh.flexneri and Salm.enterica were achieved by treatment with 05kGy 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 (20logCFUcm(-2)) by treatment with 15kGy X-ray. Treatment with 15kGy X-ray significantly reduced the initial inherent microflora on skin of whole mangoes and inherent levels were significantly (P<005) lower than the control sample throughout storage at 22 degrees C for 30days. Significance and Impact of the StudyFresh produce was associated with 770 outbreaks between 1990 and 2005, resulting in 35060 cases of illness that costs the US $39 billion annually. The food industry is looking for new preservation methods. This investigation indicated that X-ray treatment was very effective against Escherichia coli O157:H7, Listeria monocytogenes, Shigella flexneri and Salmonella enterica and inherent microflora on whole mangoes which could offer an applicable approach to control pathogens and spoilage bacteria for the mango industry.