Silicone tube

I had a complaint after a full refurbishment on an old La Pavoni pump machine that the coffee tasted “funny”. After a process of elimination it turned out to be the silicone tube which ran from the water reservoir to the pump. On replacing this, the “chemical taste” disappeared. I had never had this problem before so I did some investigation and it seems not all Silicone is “created equal”

 Silicone is quantified by its curing process and the amount of fillers in the formulation. The crosslinking or polymerisation of the silicone is achieved in the main by Platinum (addition polymerisation) or by organic peroxides (free radical polymerisation). Organic (aromatic) acids in peroxide-cured tubings are believed to contribute to the pH reduction and Total Organic Carbon seen in water extracts and increased organic extractables

Is peroxide cured silicone tube suitable for the specific application of potable water delivery in coffee machines? My answer based on the available studies is a yes but must be coupled with significant and careful post-cure procedure. Click on the photo for the full article