Data model needs normalization and relational integrity.

[metaperl]

ingredients = db.Column("ingredients", db.Text)

If you want a normalized database then Ingredients should be in a different table/tables.

categories = db.Column("categories", db.Text)

The categories most definitely should have an m-to-n relation with the recipes.

rating = db.Column("rating", db.Integer)

Who is rating the recipe and how? Shouldn't the rating be tied to the person rating it? And if so, you need to have a mapping table that contains user_id, recipe_id and rating.

image = db.Column("image", db.Text)

There can be only 1 image per recipe?

class Categories(db.Model):

What is this table doing? And why is there no relational linking between this and the Ingredients table?