How the bean switch MUST work

It’s not a secret that the popularity of machines with swappable bean hoppers using 1 grinder is increasing (Delonghi Rivelia, KitchenAid machines). However, to switch between beans, you should put 2-3 cups of coffee to get the second type or use “purge beans” program that’s also a beans waste. Why so?

In almost all bean to cups, a significant amount of coffee is stayed in burrs and a shaft between the grinder and the brewing unit. That’s why manuals require to put 3 cups of coffee after grind setting adjustment to feel the difference and you feel the spoilt coffee after the long period of downtime, for example, after vacation.

Nevertheless, there’re machines that allow you to use different beans more efficiently using 1 grinder. Of course, it’s not so flexible compared to machines with 2 grinders (Delonghi Maestosa, Jura J8 Twin), but they’re bigger and sometimes more expensive. They’re Melitta Barista TS and Miele with CoffeeSelect function (in CM7 series). How it works?

Firstly, the grind burrs and the shaft are located not horizontally, but angled towards the brew unit. As a result, there’s almost no coffee remaining in the shaft.

Secondly, they’re equipped with controlled flaps in hoppers. They dose the amount of beans put in the burrs and block the beans flow to grind them remaining until they’re over. Here’s the demo of how it works in Melitta Barista TS. The demo of Miele CoffeeSelect is in comments (it’s not allowed here to make more attachments).