جستجوی مقالات مرتبط با کلیدواژه « shrimp » در نشریات گروه « پزشکی »

The food lasting and its persistence can be increased by adding plant essential oils to the edible films such as chitosan. In the view of the increasing use of nanotechnology in the production of antimicrobial agents and the improvement of the properties of nano-sized compounds in comparison with the primary compounds, the antimicrobial properties of nano-chitosan with marjoram essential oil concentrations to increase the shelf-life of shrimp at refrigeration temperature has been studied. In this study, 1% and 2% concentrations of marjoram essential oil individually and with nano-chitosan with the concentration of 2% was prepared. Six different treated groups were examined for microbial, chemical, and sensory evaluations for 14 days. The results of this study showed that during storage time the total amount of volatile nitrogen increased significantly (P≤0.05), which is the indication of shrimp protein hydrolysis. there was no significant difference between treatments in terms of pH. The amount of malondialdehyde decreased up to day seven and was increased afterward. The coliform bacteria and Staphylococcus aureus count showed a significant difference between the control and other treatments, and with increasing storage time the bacteria count decreased. According to the results, nano-chitosan containing marjoram essential oil is a very suitable substitute for chemical and industrial coatings.

Shrimps (Litopenaeus vannamei) include high market prices and nutritional values; therefore, they are important aquatic resources worldwide. However, the shelf life of shrimps is limited due to microbiological deterioration during their storage. In recent years, several methods have been used to improve the quality of shrimps during cold storage. One of the most important methods includes use of edible coatings. Therefore, the objective of this study was to assess effects of active edible coatings from quince seed mucilage and green tea extract (as an antimicrobial antioxidant compounds) on physicochemical and quality properties of shrimps during cold storage.

This study assessed effects of quince seed mucilage (QSM) coating combined with green tea extract (GTE) on color, pH, total volatile basic nitrogen (TVB-N), texture and microbial quality of the Pacific white shrimps (Litopenaeus vannamei) within 10 days of cold storage.

Results showed that pH and TVB-N values significantly increased (p<0.05) in shrimps treated with QSM coating combined with GTE. Hardness and springiness of the shrimps were improved by increasing the concentration of GTE, compared to controls. Total aerobic plate counts of the shrimps treated by QSM coating combined with GTE were lower than those of controls. The total color difference (∆E) of the controls was lowest than that of other treatments at the end of the storage time. The a* value of the shrimps decreased from -0.87±0.21 to -5.05±1.08 (showing the attitude to greenness) and the b* values increased from 1.44±0.84 to 16.47±1.61 (showing the attitude to yellowness).

These results have suggested that the QSM and GTE coating can decrease spoilage and decomposition that cause quality loss of shrimps.

After cellulose, chitin is one of the most important polymers in crustaceans, insects, and fungi. Chitosan is one of the most important derivatives of chitin, which has important characteristics including degradability, non-toxicity, and biocompatibility antimicrobial and antioxidant properties.

Chitosan was extracted from Penaeus semisulcatus shrimp using chemical methods and the degree of its austenitization was determined using a sub-red spectrophotometer and XRD. The nanoparticles were then synthesized using the ionic gelation method and analyzed through SEM. The antimicrobial effects of nanoparticles were also evaluated using antimicrobial tests on Listeria monocytogenes and Salmonella typhi.

Nanoparticles have antimicrobial activity and can inhibit bacterial growth at different concentrations.

Chitosan nanoparticles have an inhibitory effect on Listeria monocytogenes, which is a gram-positive bacterium.

Regular consumption of seafood has been widely recommended by the authorities. However, some species especially benthic crustaceans accumulate heavy metals. In addition, the health risks associated to the consumption of such seafood might increase if the consumers use cooking methods that enhance the concentration of heavy metals. In this study, the effects of different cooking methods (boiling, steaming and frying) on the concentrations of lead (Pb) and cadmium (Cd) in shrimp and lobster were studied. Samples were prepared by wet digestion and the contents of heavy metals were measured by graphite furnace atomic absorption spectrophotometer. Mean concentrations of lead and cadmium for raw samples of shrimp and lobster were 75.67±15.31 and 26.00±8.00 µg/kg and 316.67±66.58 and 195.33±131.46 µg/kg respectively. The findings indicated that the highest contents of lead and cadmium were observed in the fried samples (p<0.05), however the differences were not significant for cadmium. According to the results, boiling and steaming are suggested as the best cooking method to provide healthful seafood.

Vibrio species are the major seafood-borne bacteria that are frequently associated with the consumption of contaminated sea food. A total of 113 samples including 58 fish and 55 shrimps were studied for the possible contamination with Vibrio species. A biochemical protocol was applied for the identification of the Vibrio isolates and Polymerase Chain Reaction (PCR) was carried out to confirm the strains. The results indicated that 25 samples (22%) were contaminated with Vibrio species. Among Vibrio isolates, Vibrio harveyi was the species most frequently isolated (11.5%), followed by followed by V. parahaemolyticus, V. vulnificus, V. alginolyticus and V. mimicus. Vibrio cholerae was not detected in the studied samples. The results of this study indicated that fish and shrimp from the Persian Gulf regularly contain pathogens that might affect the public health