Hi Asli ,
In the domain model , you can create an attribute related to the duration in the entity you created for the food . You can put the data you want in microflow in this attribute. I hope it works for you
Did you try doing one of the Mendix learning paths? I can recommend them: they are free, excellent and quick way of getting started in Mendix.
A good starting point would be https://academy.mendix.com/link/paths/83/Build-an-App-in-Mendix-Studio