الفهرس | Only 14 pages are availabe for public view |
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 223 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 |