Hello,
I am interested in your project, I have experience with microcontrollers and automation projects.
Since your design is a prototype I propose using a preexisting board as your sample, as it saves time in hardware developing.
Teensy 2.0 or Arduino Nano are perfect examples.
Once the necessary logic for temperature control, adding components, and mixing has been developed, and debugged we can move to the hardware design phase of your project either from 0 or with the board as part of the solution.