الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Increasing demand for ready-to eat food has encouraged the production and safe of minimally processed fruits and vegetables. This fresh-produce undergoes extensive microbial contamination during processing steps. The present study was designed to include three parts of work. In the first part, a limited survey (15 samples of each product) of minimally processed vegetables and fruits (fresh-cut carrots, mix vegetables salad and fresh-cut pear) was conducted to evaluate their microbiological quality. In the second part of the work, the radiation resistance of the pathogenic bacteria which were isolated from these fresh produce was studied. In the third part of the work, the packaged fresh-cut carrots, mix salad and fresh-cut pears were exposed to different doses of gamma radiation, and then stored at refrigeration temperature. The effect of gamma irradiation dose on the microbiological, biochemical and sensorial quality of these products was studied immediately after irradiation and during subsequent refrigeration storage. The results of the microbiological evaluation showed that the studied minimally processed vegetables had high microbial counts. In some samples total aerobic bacterial counts reached 106 to 107 cfu∕g. Indicator microorganisms (coliform bacteria, E. coli,, Enterococcus faecalis) were found in almost all examined samples pathogenic bacteria. from some samples. Pathogenic bacteria such as Staphylococcus aureus, Listeria monocytogenes, Aeromonas hyDROPhila and Salmonella were also isolate from some samples. The results of radiation resistance indicated a wide variation in the sensitivity of the studied pathogens to gamma radiation. Enterococcus faecalis and Listeria monocytogenes had the highest radiation resistant, while E. coli and Aeromonas hyDROPhila were the most sensitive to gamma radiation. Irradiation dose of 4 kGy was identified to be the optimum for fresh-cut carrots. This irradiation dose greatly reduced the microbial counts and extended the shelf-life to 21 days at 4°C±1 with minimal changes in biochemical, physical and sensorial quality. Fresh-cut carrot samples exposed to this irradiation dose were free from all pathogens. Irradiation dose of 3 kGy was identified to be the optimum for mix salad. It improved its hygienic quality and extended its shelf-life to 15 days at 4°C±1 without impairing the quality attributes. Irradiation dose of 2 kGy in combination with dipping fresh-cut pears in water containing 2%ascorbic acid + 1% calcium lactate prevented enzymatic browning and enhanced firmness of fresh-cut pear samples. This combined treatment did not affect biochemical, physical and sensorial quality attributes.