From Brew to Pew: Why does your reusable coffee cup smell so bad?

Have you ever reached for your trusty reusable coffee cup only to recoil at the pungent smell that greets you? Why does it smell so bad?

Bacteria, yeasts and mould decompose your leftover dregs of coffee, releasing chemicals from both the decomposed food and from the microbes themselves. Yuck!

But you washed it. So why does washing not help?

So many reusable coffee cups are forms of plastic. From bamboo reusable cups that need to use melamine resins to hold the bamboo fibres together (plastics) to cups made from recycled plastic bottles (so still plastic). These plastics are made up of long chains (polymers) of repeating units of atoms (monomers). These chains layer over each – imagine strands of pearls placed on top of each other. Depending on the plastic, large molecules like water can’t pass through these layers whilst other molecules, some smelly, can be absorbed. This is why dogs can smell treats sealed in plastic. The chemicals released from your morning flat white make their way through these layers and hide there, waiting patiently for your next coffee to go(though they will, eventually, get bored and dissipate).

Another thing to consider is the microplastics and toxins that are making there way into your caffe latte. Cups made from recycled plastics will release microplastics into your morning brew, with the health effect of microplastics still yet to be fully understood. With bamboo based cups it is important to look into the toxins that may be escaping into your coffee to-go, as they have been seen to degrade when used with hot liquids.  

Solution?

Buy a stainless steel reusable coffee cup to save your nose and the planet!

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