You can set a flag per PID - product ID, being red, blue, and green. This flag will then display on the product in the ordering screen. These flags can be red on mass via the import/export file available in the mini market section.
Click into the Admin Cogs along the top bar.
From the left click into Mini Markets and Edit the required mini market.
Click into the Import/Export tab and click Export Products.
Once the file has downloaded and opened you can update the flags between True (on) False (off) in the following columns:
Green Flag - Column AA.
Blue Flag - Column AB.
Red Flag - Column AC.
Save the file and import it back in on the same page as the above steps via Import Settings and Products option.