Escherichia coli is a faecal indicator and certain virotypes are known as pathogens. Therefore, detection and prevention of E. coli in food is very important. The existing rapid methods concentrate on detecting the pathogenic E. coli instead of total E. coli population. Present study evaluates the use of two molecular markers (uidA and flanking region of uspA) specific for the E. coli in combination with microbiological method for confirmation. Majority of the isolates (77%) were positive for both the genes tested. However, 22% of the E. coli isolates were positive for any one of the two primer sets [uidA (9%) and flanking region of uspA (13%)]. High levels of E. coli incidences (92% samples) were observed in beef while low occurrence (19% samples) was found in sprouts. Low percentage (7.3%) of E. coli isolates was positive for virulence genes tested (lt, ipaH, aggR, eaeA, stx1 and stx2). Two isolates were positive for stx genes. However, none of the isolates including stx positive isolates were E. coli 0157:H7. Maximum number of the E. coli (44%) isolates was characterized under phylogenetic group B2. This phylogenetic group comprises of extra intestinal and virulent E. coli strains.

Aeromonas, important human and fish pathogens, can form biofilm on food and food‐contact surfaces that may act as a source of cross‐contamination in the food‐processing facilities. An investigation was undertaken to evaluate the impact of various food‐related conditions (media composition, temperature, pH, salt, and food preservatives) on the biofilm formation by 10 different Aeromonas strains, belonging to six species, using polystyrene microtiter plate‐based crystal‐violet assay. These strains were vastly diverse in their biofilm forming abilities with the majority of them producing weak biofilm in TSB and M9 minimal medium. Among various conditions, majority of the strains formed the highest biofilm at low temperature (10°C) and acidic condition (pH 5). Biofilm formation for most of the strains reduced with an increase in NaCl concentration. The results indicate that various abiotic stresses encountered in food environment affect the production of biofilm in Aeromonas strains and is mainly a strain‐specific phenomenon. Practical applications The present study reports the biofilm formation by Aeromonas species under different food‐related environmental stress conditions. It will help food processors and regulators to optimize prohibitive measures to prevent biofilm formation and reduce the health risks related to biofilm‐forming Aeromonas strains.

Specific group of people, with impaired immune system, are recommended to consume pathogen-free foods. In this study, microbiologically safe ready-to-eat (RTE) mung bean sprouts were developed using combination treatment (CT) with 200 ppm sodium hypochlorite and 12 kGy dose of gamma radiation. Microbiological analysis of combination-treated sprout samples showed complete elimination (<10 CFU g À1 of sprouts) of microbial load in these samples, even during storage at 4°C up to 12 days. Combination treatment and storage period did not have any significant effect on the sensory qualities of RTE mung bean sprouts. However, reduction in the firmness and vitamin C content of combination-treated sprout samples, similar to other food processing methods, was observed. These results suggest that CT is effective in sterilisation of mung bean sprouts. These sprouts can be included in the diets of special target groups and thereby improve in their quality of life.

Summary Although ionising radiation has been shown to kill human pathogens Shigella spp. and Aeromonas spp. on various food products, there is lack of information regarding the relative efficacy of gamma radiation against their free‐living planktonic and biofilm‐associated cells. The radiation sensitivity (D10 values) of planktonic, glass‐ and carrot‐associated biofilm cells of Shigella spp. and Aeromonas spp. was determined by forming biofilms on sterile glass and carrot surfaces, incubated at 37 °C (Shigella spp.) and 30 °C (Aeromonas spp.) for 48 h. No significant difference in the D10 values of planktonic and glass‐associated biofilm cells of Shigella spp. and Aeromonas spp. was observed. However, significant increase in the D10 values of carrot‐associated biofilm cells as compared to planktonic and glass‐associated biofilm cells of Shigella spp. and A. hydrophila A331 was observed, whereas A. salmonicida Y567 showed insignificant difference. SEM analysis further validated the formation of biofilm on the carrot and glass surfaces. The antimicrobial effectiveness of ionising radiation against both Shigella spp. and Aeromonas spp. is affected by growth form, strain and nature of attachment surface.