Polish Sourdough Rye Bread

Ingredients

• ✓ 2 (.25 ounce) packages active dry yeast
• ✓ 1 teaspoon white sugar
• ✓ 2 cups water
• ✓ 4 cups rye flour
• ✓ 1 cup buttermilk, room temperature
• ✓ 1 teaspoon baking soda
• ✓ 1 tablespoon salt
• ✓ 8 cups bread flour
• ✓ 1 tablespoon caraway seed