الفهرس 
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Abstract
The present study aimed to evaluate the effect of Gum Arabic,
gelatin and agar films with different component in the treatments of
potato tubers, tomato and green bell pepper fruits as edible coatings
and their effect on microbial load and physical characters at cold and
ambient storage temperatures to extend the crops’ shelf life for export
and local markets.
Fifteen groups of tested crops’ samples (potato tubers, tomato
and green bell pepper fruits) were collected from local market, Cairo,
Egypt. The first group was left to spoil for isolating the spoiled
microorganisms that affect these crops. The antimicrobial activity of
EDTA, L. paracasei and Gum Arabic was detected. Mature crops’
samples that are similar in shape, color, size and free of any defect
were washed with tap water then dried at ambient air conditions
before coating. These samples were divided into 14 groups; one
group was uncoated as control samples, one coated with wax and the
others coated with different edible films i.e., GA, gelatin and agar in
addition to their treatments. Half of these groups stored at cold and
the other stored at ambient temperature. During storage period,
physical (pH, weight loss) and TSS for the best film) and microbial
analysis (total bacterial, Enterobacteriaceae, mold and yeast count)
were conducted at time intervals (3,5,7,10,15,20,25,30 and 35 days)
of storage period. Scanning Electron Microscopy (SEM) and the
Cytotoxicity test was conducted for the best film i.e., GA/EDTA/L.
paracasei supernatant edible film.
1- The isolation of spoiled microorganisms revealed five gram
negative (G-ve) bacterial isolates include, E. coli, Salmonella typhi,
pseudomonas fluorescenc, Ralstonia solanacearum and Citrobacter
Summary
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amalonaticus, two gram positive (G+ve) bacteria; Staphylococcus
aureus, Bacillus cereus (from potato tubers only), three fungal
isolates, (Aspergillus flavus, Penicillium sp. and Fusarium.
oxysporum) and yeast cells.
2- The results of antimicrobial activity indicated that all the tested
compounds (EDTA, L. paracasei supernatant and GA) inhibited the
tested isolates by different efficiencies.
3- GA/EDTA/ L. paracasei supernatant edible film succeeded the
other films and their treatments and the untreated samples (control) in
extending the shelf-life of treated crops’ samples as well as wax
during storage days, whereas it lowered microbial load, diminished
weight loss and TSS and showed better control on pH.
4- Pictures of potato tuber’s peel, tomato fruit’s peel and green bell
pepper fruit’s peel were captured by scanning electron microscope
(SEM) to study the physical structure of coated tubers and fruits with
the best film (GA/ EDTA/ L. paracasei supernatant edible film)
compared to uncoated (control) ones, they show better structure
content, homogenization and minimum pores and cracks compared
with controls’ pictures.
5- The cell growth inhibitory capacity of the promising edible film
GA/EDTA/L. paracasei supernatant was tested, no cytotoxicity was
expected on normal cell line, the film is safe for normal cell line, but
the film has a significant effect on cancer cell line.
6- Accordingly, it is recommended to use this film as nutritionally
beneficial, eco-friendly, biopreservative edible film