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Showing 2 results for Oroojalian
Volume 19, Issue 3 (5-2017)
Abstract
In this research Kelussia odoratissima Mozaff. leaf extract was used for the green synthesis of silver nanoparticles (AgNPs). At first we compared antioxidant activity of different extracts of K. odoratissima. Then solution containing silver nitrate was treated with the extract which showed high antioxidant activity. Synthesized AgNPs were evaluated by analyzing the excitation of surface plasmon resonance. TEM analysis was also used for nanoparticle characterization. Antibacterial activity of the solution containing AgNPs was measured by microdilution test. Common food contaminant bacteria such as gram-positive (Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes) and gram-negative (Escherichia coli O157: H7, Salmonella enterica and Pseudomonas aeruginosa)were used for the evaluation. The aqueous extract showed the highest antioxidant activity and the solution was used for the green synthesis of AgNPs. The particle diameters were calculated to be 20-40nm with -17 to -19.9 mV zeta potential. The TEM micrographs showed that the AgNPs are nearly spherical in shape and highly monodispersed. MIC of the AgNPs against gram-positive and gram-negative bacteria was between 0.012-0.025 and 0.006-0.012 mg/ml respectively.
Volume 19, Issue 128 (October 2022)
Abstract
In this study, the extract of Hypericum Perforatum aerial organs was prepared by hydro alcoholic solvent and the extract was coated in calcium alginate nanoparticles and the antimicrobial properties of the extract and nanoparticles on four gram-positive, gram-negative yeast and mold groups were investigated and Nanocapsules containing extract were evaluated on the shelf life of white cheese. To prepare Nano-extracts, the emulsion production method of alginate-calcium Nanocapsules containing the extract was used. The production of Nanocapsules containing the extract was done by adding calcium chloride nanoparticles to the alginate Nanoemulsion containing the extract in a ratio of 1 to 6 for 4 hours. To prepare the cheese, Staphylococcus aureus, Escherichia coli, and Candida albicans yeast are inoculated separately into the milk at a rate of 103 CFU / ml and then added calcium chloride, Rennet enzyme, extract and Nanocapsules containing extract to milk were done and the microbial properties of the cheese samples were evaluated on the day of production and up to seven days after. The results of particle size determination, particle size dispersion index, and potential and efficiency of encapsulation for the production of Nanocapsules containing Hypericum Perforatum extract and its microscopic examination confirmed the production of nanoparticles with appropriate efficiency of encapsulation. Also, the results showed that for all three microorganisms tested, the sample containing Nano-extract was able to reduce about one logarithmic cycle of the inoculated microorganism and during the shelf life of gram-positive, gram-negative and yeast had a downward trend (P <0.05). The results of the present study showed that using plant extracts containing antimicrobial compounds such as extracts of aerial organs of Hypericum Perforatum plant, especially in Nanoparticle and in appropriate quantities, as an alternative to synthetic preservatives, produce a healthy food product and with longer shelf life, it will be possible.
