One-third of samples of milk and dairy products乳制品 analysed in various restaurants exceed the microbe细菌，微生物 contamination污染，玷污 limits set by the European Union, according to a study carried out by researchers from the University of Valencia (UV). The experts advise against keeping milk in jugs水壶，监牢 and suggest that these foodstuffs³ need to be better handled. "Out of all the dairy products we analysed, 35% of the samples exceeded the maximum contamination levels established by EU law for enterobacteriaceae肠杆菌科, and 31% exceeded the limits set for mesophilic亲中介态的，嗜常温的 aerobic⁴ microorganisms嗜氧微生物 (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批次 of milk and ready-to-use milk derivatives派生物 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食物性病原体与疾病, show that one-third of the samples had some kind of microorganism contamination and were not fit for human consumption.

"Luckily none of the batches⁵ we analysed tested positive for Staphylococcus aureus金黄色酿脓葡萄球菌, Listeria monocytogenes单核细胞增多性李斯特氏菌 or Salmonella沙门氏菌 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 jugs¹ or stainless⁷ steel thermos⁸ flasks⁹保温瓶) 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 utensils¹⁰

The experts advise that, when using milk in any way, it is important to clean jugs, thermos flasks and the steamers of coffee machines thoroughly¹¹ and frequently, using the right kind of hygienic卫生的，保健的 sponges海绵 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盖子，眼睑 are better, since tetrabricks opened with scissors are more exposed to microbial proliferation增殖，扩散, and are especially vulnerable to enterobacteriaceae.

In terms of dairy products prepared in the restaurants themselves (custards奶油冻, mousses奶油冻，摩丝, puddings and crème乳油，奶油 caramels焦糖), custards (natillas) had the highest levels of contamination with microorganisms. This may be due to the fact this was the only foodstuff² 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饼干，小点心 on top of the dish.

In line with一致，符合 previous studies, the researchers also showed that adding cinnamon肉桂 to dairy products led to reduced microorganism contamination, since this substance helps to eliminate microorganisms such as Escherichia coli大肠杆菌, Listeria monocytogenes and bacteria from the Salmonella family.