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

Author:
Mahmoud, B.S.M., Nannapaneni, R., Chang, S., Coker, R.
Source:
Letters in applied microbiology 2016 v.62 no.2 pp. 138-144
ISSN:
0266-8254
Subject:
Escherichia coli O157, Listeria monocytogenes, Salmonella enterica, Shigella flexneri, X-radiation, air drying, ambient temperature, food industry, fresh produce, mangoes, pathogens, population, spoilage bacteria, yeasts
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 (P < 0·05) lower than the control sample throughout storage at 22°C for 30 days. SIGNIFICANCE AND IMPACT OF THE STUDY: Fresh produce was associated with 770 outbreaks between 1990 and 2005, resulting in 35 060 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.
Agid:
4801329