ABSTRACT
Background: Vibrio paraheamoloyticus is one the causative agents of vibriosis with high mortality in farmed fish and shrimp and under predisposing conditions
Objectives: This study was aimed to assess the effect of gamma irradiation on the inactivation of V. paraheamoloyticus under fresh and freeze-dried conditions
Methods: Vials of 0.5 ml fresh culture of the bacterial suspensions at 1.5[asterisk]10[10] cfu/ml were subjected to 1, 1.5,2, 2.5, 3 and 4 KGy. Also, vials of 0.5 ml freeze-dried culture of the bacterial suspensions at 1.5 x 1010 cfu/ml were subjected to 2, 4, 7 and 8 KGy. The bacterial growth behavior was then evaluated on fresh medium
Results: The obtained results showed that the minimum doses of 4 and 10 KGy were sufficient for the inactivation of fresh and freeze-dried bacteria, respectively
Conclusions: The result of this study shows that inactivation of V. paraheamolyicus in fresh culture condition requires below half- dosage of gamma ray required for the inactivation of the freeze- dried of bacterial cells
ABSTRACT
The approaches chosen for control of Outbreaks of infectious diseases in Aquatic farming industry include improvement of environmental conditions, stocking of specific pathogen free [SPF] brood stockings, and application of vaccines and immunostimulants. Despite numerous studies on the effects of Ergosan on immune system of aquatic animals, there is no data available on antioxidant activities of Ergosan. The aim of the present study was to investigate and evaluate the radical scavenging activities of Ergosan extract by DPPH [1, 1-diphenyl-2-picrylhydrazyl] free radical scavenging assay, and the possible effects of gamma irradiation on its assumed radical scavenging activities. Ergosan was irradiated with gamma rays [10, 20, 30, 40 and 50 kGy], and their structural changes and antioxidant activities were investigated by UV absorbanceand DPPH [1,1-diphenyl-2-picrylhydrazyl] assays, respectively. The gamma irradiation decreased the average pH of irradiated Ergosan, and UV spectra of irradiated product showed increase in the number of carboxyl groups and double bonds. Our results showed that 30 kGy irradiated Ergosan suspension had significant higher level of antioxidant activity in comparison with non-irradiated Ergosan [P<0.05]. Also, the reducing power values of 30 and 50 kGy irradiated Ergosan were higher than that of nonirradiated [P<0.05] and the other doses of irradiation couldn't make any significant difference in reducing power of Ergosan. Results indicate that the 30 kGy irradiated Ergosan might be an appropriate candidate for the use in aquatic animal diets as a natural antioxidant agent besides its immunostimulant role
Subject(s)
Animals , Gamma Rays , Adjuvants, Immunologic , Diet , Aquatic OrganismsABSTRACT
Saffron, the dried stigmas of crocus sativus, is the world's most expensive spice which has been used as food additive and flavoring agent. The aim of the present study has been to investigate the combination effects of gamma irradiation and silver nano particles packing on the chemical properties of saffron during storage time. A combination of hurdles can ensure stability and microbial safety of foods. To investigate the combination effects, saffron samples were packed by Poly Ethylene films which were possed up to 300 ppm nano silver particles as antimicrobial agents and then irradiated in cobalt-60 irradiator [gamma cell Model: PX30, dose rate 0.55 Gy/sec] to 0, 1, 2 ,3 and 4 kGy at room temperature. UVspectrophotometer was used to quantify the most important components crocin, picrocrocin and safranal which were respectively responsible for color, taste and odor. Statistical analysis showed that irradiation and silver nano particles films packing could increase the flavor and aroma of saffron, and the best optimum dose of irradiation was 2 kGy. Also, sensory evaluation showed no significant difference between them [P<0.05]. Hurdle technology has been more effective than irradiation or nano-silver particles packing methods. Therefore combined method can be used for microbial decontamination of saffron with no significant differences on chemical characteristics and sensory attributes