reza lorestani

The utilization of plant essential oils and extracts as antibacterial agents has given specific attention to prevent the growth of pathogenic bacteria. This work aimed to compare the effects of sodium metabisulfite and Mentha longifolia L. essential oil (MEO; 0, 0.5, 1, and 2%) for growth prevention of Listeria monocytogenes and Escherichia coli O157:H7 in peeled giant freshwater prawns under cold storage for two weeks.   The in vitro antimicrobial effect of MEO against L. monocytogenes and E. coli O157:H7 was evaluated using disk diffusion method. In this study, the effect of direct addition of MEO (0, 0.5, 1, and 2%) and sodium metabisulfite 1.25% to prawn samples were evaluated.  The major chemical constituents of MEO were found to be pulegone (47.20%), eucalyptol (22.72%), and menthone (13.44%). The diameter of inhibition zone of MEO against L. monocytogenes and E. coli O157:H7 were determined to be 9.45 ± 0.23 mm and 6.37 ± 0.02 mm, respectively. Our findings indicated that MEO 0.5, 1, and 2% significantly decreased the growth of L. monocytogenes and E. coli O157:H7 in comparison with the control group (P < 0.05). Sodium metabisulfite was more effective than MEO in inhibiting the growth of L. monocytogenes and E. coli O157:H7 added in raw freshwater prawns.  The findings of this work indicate that MEO can successfully prevent the growth of L. monocytogenes and E. coli O157:H7 and improve the safety of raw freshwater prawns under prolonged refrigerated storage.

The aim of this study was to determine the optimal levels of Na+، Ca+2، k+، Sucrose and osmotic pressure in saline activator solutions for increasing the duration of spermatozoa motility in Barbus sharpeyi. Also، the effect of different saline activator solutions were assessed on VCL، VSL and Linearity of spermatozoa cells in B. sharpeyi. Results showed that Na+ ion concentration of 100 mML-1، 50 mML-1 of k+ and 2. 5 mML-1 of Ca+2 have created the optimal conditions for stability of spermatozoa movement. The optimal level of osmotic pressure in sperm activator solution was 179±3. 4 mOsmol kg-1. Results showed that the highest VCL and VSL were assessed by 50 mM NaCl. Also، 100 mML-1 of Na+ and 20 mML-1 of Tris induced the highest Linearity percentage in B. sharpeyi spermatozoa (p≤0. 05). In final conclusion، usage of extender solutions containing Na+ ion concentration of 100 mML-1، 50 mML-1 of k+، 2. 5 mML-1 of Ca+2 and 150 mML-1 sucrose is suggested separately for obtaining the optimal motility of spermatozoa in Barbus sharpeyi. Also، the mixed extender solution containing concentration 50 mML-1 of NaCl، 30 mML-1 of KCl، 2. 5 mML-1 of Ca+2، 30 mML-1 of Tris and 189 mOsmol kg-1 of osmotic pressure is suggested for activation of spermatozoa motility in Barbus sharpeyi.