الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Nanotechnology is concerned with the design, manufacture, and use of structures by controlling the size and shape of materials at the nanometre scale. Furthermore, nanoparticles have already been used in many aspects of human existence. Nanocomposites have already spawned a slew of developments with potential uses in the food packaging industry. In reality, the application of polymer nanotechnology can extend and implement all of the package’s primary tasks (containment, protection and preservation, marketing and communication). This is why many of the world’s largest food packaging companies are actively investigating the potential of polymer nanotechnology in order to develop new food packaging materials with improved mechanical, barrier, and antimicrobial properties, as well as the ability to trace and monitor the condition of food during transportation and storage. This study concerned with production of a novel and effective nanotechnology-based polymer materials for food packaging. In this study, Penicillium roqueforti (GenBank Acc. No. MK805460.1) was isolated and molecularly identified. Penicillium roqueforti MK805460.1 was introduced into a mixture of ferric chloride hexahydrate (103 M) and ferrous chloride tetrahydrate (103 M) (2:1 ratio) for the biosynthesis of iron oxide nanoparticles in a quick, cost-effective, and successful way. The biosynthesized IONPs were modified by SiO2 shell using the stöber method.
The nanoparticles were also characterized by UV-Vis spectroscopy, Energy Dispersive X-ray (EDX), Transmission Electron Microscopy (TEM), and X-ray diffraction (XRD). The biosynthesis of iron oxide nanoparticles was validated by UV-Vis spectroscopy, which revealed the presence of wavelength band in the range of 204-266 nm. Furthermore, TEM indicated the formation of spheres 5-16 nm iron oxide nanoparticles. Antibacterial activity was assessed at different concentrations (50, 100, 150 and 200 μg/ml) against Gram-positive bacteria (Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633), and Gram-negative bacteria (Salmonella typhimurium ATCC 14028, Escherichia coli ATCC 8739), by employing agar well- diffusion and kinetic bacterial growth methods. In addition, the antifungal activity of the nanoparticles was tested against Aspergillus niger, Aspergillus fumigatus and Aspergillus flavus, using dry-weight mycelial method.
It was noted that the antibacterial effect of IONPs and Si-IONPs against G (+ve) and G (-VE) bacteria was showed highly statistically significant difference with the different concentrations. By mean as concentration was increased the diameter of the inhibition zone was increased. It was observed that Gram-negative bacteria were more resistant to IONPs and Si- IONPs than Gram- positive bacteria.
According to the in vitro cytotoxicity study, the MTT results were showed no alternation on the normal cell viability with different concentrations (50,100 and 150 μg/ml) of Si-IONPs. However, at 200 μg/ml there was a decrease in cell viability by 16.3 % after 48h at 37 ºC.
In vitro spectral behavior of two biogenic amines (Histamine and Tyramine) was investigated in the presence of various concentrations (50, 100, 150, and 200 g/mL) of IONPs and Si-IONPs. In this study, the silica improved the bonding between IONPs and biogenic amines.
Ras cheese is a well-known Egyptian hard cheese. This cheese would include a variety of microorganisms derived from the used raw milk and the surrounding environment. Certain of these microorganisms contribute to the development of flavour and body texture, while others are unpleasant and create some flaws in this cheese. In this study, 100 µg/ml Si-IONPs nanocomposite thin film polymer was developed for Ras cheese coating. The physicochemical and microbiological study was carried out on the control Ras cheese (coating polymer without nanocomposit) and the treated Ras chesse (coating polymer with nanocomposie).
Chemical examination revealed that the total protein, fat content, acidity, total solids, and total N2(%) values were significantly higher in the untreated group than in the treated group during the ripening priod. Although the moisture (%) and pH values were significantly lower in the treated cheese samples.
However, there was a statistically significant difference in the microbial populations of treated and untreated cheese samples throughout the ripening period. The total bacterial count (TBC) and coliform counts in the treated cheese samples were considerably lower during the ripening period. However, the lactic acid bacterial population of Ras cheese from untreated and treated samples was considerably increased (three folds) after four months, and then was decreased to half only in untreated cheese samples after six months. Yeast and mould were isolated from untreated cheese samples after 2 months and rise to 27.67 x102 cfu/gm after 6 months. After 6 months, they appeared by total count 1.33 x102 cfu/gm in treated cheese samples.
According to the coliform populations throughout the ripening period, there was a very statistically significant difference between treated and untreated cheese samples. The count of S. aureus was demonstrated a highly significant difference between the treated and untreated cheese samples. According to the results of HPLC analysis of Ras chesse samples to detect biogenic amines, the treated cheese samples were devoid of all tested biogenic amines. While tyramine levels in untreated cheese samples was progressively rose to 16.67 mg/100g after 6 months. The results demonstrated the existence of putrescine and spermine in untreated cheese samples. Also, after 2 months, the spermine level was 32.4 mg/100g, which was raised to 49.2 mg/100g after 4 months and finally to 50.75 mg/100g after 6 months.