This idea is a follow-up from the previous Idea #35, if you have all the food from the fridge in your app why not enter the expiration date and know which food is going to expire soon. This app or service could be with the previous app or a standalone one.
How does it work
While entering or scanning every food item, the app will have an extra field to enter the expiry date. For certain products that normally don’t have an expiry date, it could deduce the expiry date from the date you’ve bought it. The user will need to enter where the item is stored (cupboard, fridge, freezer) to give a more accurate estimate. Another way would be to detect the date by taking a picture of the date, but that is probably harder to implement.
How does the app notify the user
The app could notify via daily push notification or email when food is almost expired. You could even send notification via text message that is more costly for the provider usually though. It should be easy to remove items once they are no longer in the house so users don’t have notification for food that has already been eaten.
Using the previous app, when entering new items or looking for a recipe to do, the apps will suggest items that will soon expire.
I don’t see this as a paid service, maybe bundle it with another app and charge for extra functionality. The apps might run on ads and users could pay monthly to remove them. You could target ads at items that are regularly added and are expired or recently removed, making them more relevant to the user.