Seasonal distributions of heavy metal concentrations in different snail (Helix pomatia) tissues from an urban environment in Serbia.

The aim of this study was to evaluate the differences between concentrations of heavy metals (cadmium, copper, zinc, iron, and manganese) in terrestrial gastropods, Helix pomatia, collected in four different environment locations in Pancevo city, Serbia. Metal concentrations in the foot and in the digestive gland were measured. Heavy metals cadmium, copper, zinc, iron, and manganese were measured in triplicate by atomic absorption spectrophotometry. Also, this study investigated correlations between the trace element content in the soft tissues and different seasons (summer and fall). The results showed that heavy metal concentrations of the measured elements in both snail tissues were significantly higher in polluted sites when compared to the background levels in the city. In digestive gland tissues, the concentration of heavy metals was higher compared with that in foot tissues. The bioaccumulation (heavy metal concentrations in soft tissues) of heavy metals (Cd, Cu, Zn, Fe, and Mn) in snails, Helix pomatia, has been assessed and related to seasons and sites. Heavy metal accumulation in the soft tissues of snails could provide a powerful monitoring tool for the assessment of environmental heavy metal pollution.

Inhibition of Salmonella by thyme essential oil and its effect on microbiological and sensory properties of minced pork meat packaged under vacuum and modified atmosphere.

The antibacterial activity of thyme essential oil (TEO) was evaluated against four serovars of Salmonella (S. Enteritidis, S. Typhimurium, S. Montevideo and S. Infantis), experimentally inoculated (106CFU/g) in minced pork, which was treated with different concentrations of the TEO (0.3%, 0.6% and 0.9%) packaged under vacuum or MAP (30%O2/50%CO2/20% N2) and stored at 3±1°C for 15days. GC-MS analysis of the TEO was performed in order to determine composition, and the predominant constituent was thymol (50.48%), followed by p-cymene and linalool. The minimum inhibitory concentration was determined for each Salmonella serovar studied. Among the tested active compounds, thymol and carvacrol exhibited the greatest inhibitory effect followed by TEO, with minimum inhibitory concentrations of 320 to 640µg/ml. S. Enteritidis was the most sensitive serovar. During the storage period, Salmonella counts in pork were reduced by 1.69-4.05logCFU/g. The influence of TEO on Enterobacteriaceae, lactic acid bacteria and total viable count was determined in control mince with no added Salmonella. The most pronounced antibacterial effect was achieved by the combination MAP and 0.9% TEO. Although the antibacterial activities of all studied concentrations of TEO in pork were evident and significant (P<0.05), sensory analysis showed that 0.3% TEO was the most acceptable to trained panellists.