Research carried out by Aston University has shown cups left unwashed until prior to the next use pose a greater risk than those rinsed or cleaned shortly after a drink is finished.
Reusable coffee cups have grown in popularity amid suggestions the government could introduce a “latte levy” to reduce the waste created by 2.5 billion disposable coffee cups each year.
The Aston University study saw people use their coffee cups in a number of different ways over a week, from rinsing it immediately after finishing their drink to leaving the remains of the coffee in the cup and then washing it before the next use.
Professor Anthony Hilton, Deputy Executive Dean of Life & Health Sciences at Aston University, said: “Drink residues left in reusable cups are a good source of nutrients for bacteria which can multiply rapidly during storage.
“If the cup is refilled without appropriate cleaning, these bacteria can represent a significant source of contamination.
“Consumers should be mindful of reusable cup hygiene and clean them in the same way they would any other food contact surface.
“This can be easily overlooked and it can be difficult when washing facilities are not readily available following cup use and reuse, particularly when using the cup while travelling, but it is important.”
The study has led to calls for reusable cups to carry anti-microbial product protection to reduce the presence of bacteria, regardless of the frequency and timing of washing.
Paul Morris, CEO of Addmaster which is a Midlands based company that supplies specialist anti-microbial solutions globally, said: “The evidence from the study is clear.
“To have effective hygienic use in a normal reusable coffee cup, you have to wash your cup shortly after use.
“But the very nature of a reusable cup means people could be using it while they are on the move with no chance to rinse or wash it immediately after use.
“With that in mind, we need to look at methods to reduce the risk, and one way is for manufacturers of reusable cups to incorporate anti-microbial technology in their products, such as Biomaster product protection.”
Simon Ellin, chief executive of The Recycling Association, welcomed the findings and the increased use of reusable coffee cups - but urged people to be wary about the hygiene risks.
He said: “We welcome the public’s desire to reuse items such as coffee cups but would want them to do so with caution and make sure they wash their cups thoroughly and, if possible, choose one with anti-microbial product protection.”
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About Professor Anthony Hilton
Professor Anthony Hilton received the Society for Applied Microbiology Award in 2006 for his contribution to public awareness of harmful germ transmission.
He is well-known in his field and in the media for his experiments to prove the 'five second rule' on food safety and for appearing in the BBC3 documentary Grime Scene Investigation. His research interests lie in trialling more effective ways to treat bacteria such as salmonella, MRSA and Clostridium Difficile.
About Aston University
Founded in 1895 and a University since 1966, Aston is a long established university led by its three main beneficiaries – students, business and the professions, and our region and society. Aston University is located in Birmingham and at the heart of a vibrant city and the campus houses all the university’s academic, social and accommodation facilities for our students. Professor Alec Cameron is the Vice Chancellor & Chief Executive.
Aston has been a leading university for graduate employment success for over 25 years and our students do extremely well in securing top jobs and careers. Our strong relationships with industry partners mean we understand the needs of employers, which is why we are also ranked in the top 20 for graduate employability.
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