ESAG - Rapport annuel - Jahresbericht 2021

Fieldwork report of the Swiss School of Archaeology in Greece in 2021. Excavations at Amarynthos (Artemision) and Ilkizes (Drakospiti) in Euboea, Survey between Eretria and Amarynthos (Euboea), excavation on Mount Oros (Aegina), underwater research on the shipwreck at Antikythera

Quantitative real time PCR does not reliably detect single fecal indicator bacteria in drinking water

The microbial quality of drinking and environmental water is usually determined by culture-based detection of fecal indicator bacteria according to ISO reference methods 16649-1 and 7899-2, respectively. Because of an increasing demand for rapid, culture-independent methods, we tested three quantitative polymerase chain reaction (qPCR) approaches for the simultaneous detection of both, Escherichia coli and Enterococcus spp., using either 16S rRNA or 16S rDNA as a target molecule. Filter sterilized drinking water was artificially contaminated with bacteria from either high or low nutrient culture conditions and directly analyzed after membrane filtration without any other enrichment. Depending on the culture condition used, qPCR analyses revealed a lower limit of detection of 1–10 E. coli/100 ml and 10–100 E. faecalis/100 ml, respectively. In addition, the microbial quality of different surface water samples was monitored. The analyses revealed a clear correlation between viable cell counts and qPCR data. However, the safe and reliable detection of 1 CFU/100 ml failed.</jats:p

The Artemision at Amarynthos: The 2021 Season

Rapport de fouille des interventions dans l'Artémision d'Amarynthos 2022

Thermal inactivation of Salmonella spp. during conching

Although chocolate is a microbiologically stable product it has been described as a vehicle for Salmonella spp. Because of the low water activity (aw) and the high fat content of chocolate Salmonella spp. shows an increased heat resistance, even during the thermal process of chocolate making. The aim of this study was to evaluate the thermal inactivation of Salmonella spp. during conching in various masses of chocolate and cocoa butter at different temperatures (50-90°C). The effect of thermal treatment on Salmonella spp. was determined with the MPN (Most Probable Number) method. Results of thermal treatment showed approximate D-values for cocoa butter from D50°C=245 min to D60°C= 306 min, for cocoa liquor from D50°C=999 min to D90°C=26 min and for dark chocolate of D50°C=1574 min. Z-values were found to be z=20°C in cocoa liquor and z=14°C in dark chocolate. This study demonstrates that the conching process alone does not ensure the inactivation of Salmonella spp. in different chocolate masses and that an additional decontamination step at the beginning of the process as well as an HACCP concept is necessary during chocolate production to guarantee the absence of Salmonella spp. in chocolates and related products