To make the buttermilk, in a small bowl, mix 1 cup of milk with 1 tbsp of lemon juice. Allow this mixture to sit for 5 minutes.
In a large mixing bowl, combine the flour, wheat flour, salt, and baking soda. Add the egg, milk, buttermilk and melted butter to the bowl and fold until all the ingredients form a soft, sticky dough.
Grease the springform pan and pour the dough into the pan.
Bake in a preheated oven for 50 minutes or until the internal temperature is 200℉.
Remove the pan and allow to cool on a cooling rack for 15 minutes before removing the bread from the pan. Allow to continue to cool at least 30 minutes before cutting and serving.