Shorter ingredient lists can be a good rule of thumb, but things like E-XXXX can just be regulator names for regular things.

E-330 is citric acid which is lemon juice

E-621 is MSG which is just more meaty tasting salt from seaweed sources instead of rock.

The E classification is for regulation testing, not a label of how processed something is.

Another rule of thumb other than ingredient list is who made it. Your local baker will probably have a less processed method than a mega factory like Bimbo Hovis or any other macro manufacturer that can put 1000 loaves in every supermarket in the country every day