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Aims: The aim of this study was to evaluate the potential of Listeria monocytogenes to grow in mushrooms packaged in two different types of PVC ®lms when stored at 4°C and 10°C. Methods and Results: Mushrooms were packed in two polymeric ®lms (perforated and nonperforated PVC) and stored at 4°C and 10°C. The carbon dioxide and oxygen content inside the packages, aerobic mesophiles, psychrotrophs, Pseudomonas spp., Listeria monocytogenes, faecal coliforms, Escherichia coli, anaerobic spores and major sensory factors were determined. The mushrooms packaged in nonperforated ®lm and stored at 4°C had the most desirable quality parameters (texture, development stage and absence of moulds). Listeria monocytogenes was able to grow at 4°C and 10°C in inoculated mushrooms packaged in perforated and nonperforated ®lms between 1 and 2 log units during the ®rst 48 h. After 10 d of storage, the populations of L. monocytogenes were higher in mushrooms packaged in nonperforated ®lm and stored at 10°C. Conclusions: MAP followed by storage at 4°C or 10°C extends the shelf life by maintaining an acceptable appearance, but allows the growth and survival of L. monocytogenes. Signi®cance and Impact of the Study: According to this study additional hurdles must be studied in order to prevent the growth of L. monocytogenes.

Mushrooms were packed in two polymeric films (perforated and non‐perforated PVC) and stored at 17 °C and 25 °C. The carbon dioxide and oxygen content inside the packages, aerobic mesophiles, Pseudomonas spp., faecal coliforms, Escherichia coli, anaerobic spores and major sensory factors (colour, texture, development stage and presence of moulds) were determined. The non‐perforated packages had the highest contents of CO2 (6–7%), the lowest contents of O2 (0·013–0·17%) and the most desirable quality parameters (texture, development stage and absence of moulds). Pseudomonas spp. counts were around 1 logarithmic unit lower in mushrooms packaged in non‐perforated film as the O2 concentrations were lower than in perforated film. The mushrooms themselves were inoculated with an enterotoxin A‐producing strain of Staphylococcus aureus, packaged in overwrapped trays and stored at 17 and 25 °C. Staphylococcus aureus did not grow in the samples stored at 17 °C. Only slight growth was observed in mushrooms packaged with non‐perforated film after 1 day at 25 °C. No enterotoxin was detected in any package. Faecal coliform counts were <2 log cfu g−1. Escherichia coli was not isolated in any of the samples. At 25 °C, counts of anaerobic spores of around 2 log cfu g−1 were detected in those mushrooms packaged in non‐perforated film.

Aim: Optimal conditions for chlorine application to obtain a reasonable decrease in the microbial counts without damaging the appearance of artichoke and borage have been established. Methods and Results: The influence of chlorine concentration (0-200 mg l )1 ), pH, addition of organic acids, contact time and presence of protective structures on the microflora and vegetal appearance were studied. When pH was not controlled the effect of chlorine depended on its concentration until the pH increase caused by addition of chlorine reached 8AE8. Any further increase in chlorine concentration was nullified by the pH increase. When pH was adjusted to 4AE5 with acetic acid, the effectiveness increased with concentration. However, the use of citric acid to control pH caused a sharp decrease in effectiveness at concentration about 250 mg l )1 . The higher effectiveness of chlorine on homogenized plant extracts compared with the whole plant showed the impact of the vegetal structures on the resistance of the microorganisms. For artichoke, a relationship between the effectiveness of chlorine disinfection and its structures was also found. Extended washing times did not affect the total counts. However, in both vegetables, the appearance was affected by the extended contact times. Conclusions:The solutions rendering the highest microbial reduction with minimum damages were: 50 mg l )1 free chlorine without pH control for artichoke and 100 mg l )1 free chlorine at pH 7AE0 for borage. Significance and Impact of the Study: Specific conditions for chlorine disinfection of artichoke and borage were determined to reduce the microorganisms in minimally processed artichoke and borage without damaging their appearance.