I would eat the food at the store and then throw the trash away in the store's trash cans.
For things I didn't eat at the store I carried a small plastic bag to store my trash and when I got to my lodging I would throw it away. Also once you go inside the gates of a subway/train station there often seemed to be trash cans available.
For things I didn't eat at the store I carried a small plastic bag to store my trash and when I got to my lodging I would throw it away. Also once you go inside the gates of a subway/train station there often seemed to be trash cans available.