"Out of all the dairy products we analysed, 35% of the samples exceeded the maximum contamination levels established by EU law for enterobacteriaceae, and 31% exceeded the limits set for mesophilic aerobic microorganisms (which grow at an optimum temperature of between 30 and 45ºC)", Isabel Sospedra, a researcher at the Department of Preventive Medicine and Public Health of the UV and one of the authors of the study, tells SINC.
The scientists examined 265 batches of milk and ready-to-use milk derivatives in a range of bars and restaurants in Valencia, and checked whether their microbial quality fell into line with European Union regulations. The results, which have been published recently in the journal Foodborne Pathogens and Disease, show that one-third of the samples had some kind of microorganism contamination and were not fit for human consumption.
"Luckily none of the batches we analysed tested positive for Staphylococcus aureus, Listeria monocytogenes or Salmonella spp., which are pathogenic microorganisms that cause both food poisoning and toxoinfections", the study's authors says.
The researchers found differences according to the source of the sample (hot milk, products at room temperature or homemade dairy products). According to the study, 2% of the samples of hot milk (kept in jugs or stainless steel thermos flasks) tested positive for the bacteria Escherichia coli.
The team detected unsuitable practices, such as reheating milk over and over again, even in a microwave, and then pouring it back into the thermos, which increases the risk of microbial contamination. The study shows that there is a greater contamination risk from milk kept in jugs, meaning this type of container is not suitable for storing milk.
Focus more on cleaning utensils
The experts advise that, when using milk in any way, it is important to clean jugs, thermos flasks and the steamers of coffee machines thoroughly and frequently, using the right kind of hygienic sponges or cloths, which is not always the case. "Kitchen cloths are not suitable for disinfecting because of their microstructure, which means they transfer even greater levels of contamination", the scientists explain.
In terms of milk that is cold or at room temperature, this is usually kept in its original container in restaurants and bars – a plastic bottle or tetrabrick. The study shows that containers with a lid are better, since tetrabricks opened with scissors are more exposed to microbial proliferation, and are especially vulnerable to enterobacteriaceae.
In terms of dairy products prepared in the restaurants themselves (custards, mousses, puddings and crème caramels), custards (natillas) had the highest levels of contamination with microorganisms. This may be due to the fact this was the only foodstuff analysed that is further processed after being heated, say the scientists. Cross contamination could come from the hands of the person preparing the product, particularly when he or she places the biscuit on top of the dish.
In line with previous studies, the researchers also showed that adding cinnamon to dairy products led to reduced microorganism contamination, since this substance helps to eliminate microorganisms such as Escherichia coli, Listeria monocytogenes and bacteria from the Salmonella family.
Isabel Sospedra, Josep V. Rubert, Carla Soler, Jose M. Soriano, Jordi Mañes. "Microbial Contamination of Milk and Dairy Products from Restaurants in Spain". Foodborne Pathogens and Disease 6(10): 1269-1272, diciembre de 2009.
SINC | EurekAlert!
Drone vs. truck deliveries: Which create less carbon pollution?
31.05.2017 | University of Washington
New study: How does Europe become a leading player for software and IT services?
03.04.2017 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology