Now the $item->save() doesn't work anymore, since $item->ingredients isn't a array of Model_Ingredients, but an array of form data.
And I don't understand how this can work ever. There is no primery key in the tabular form set (since primary keys are ignored by the fieldset class), so how can the model know, which row we want to update?
The example doesn't talk about "ingredients", nor does it assign any array data to something that should contain models. So I think there's something wrong with your implementation.