Proof yeast in warm water for 10 minutes or until bubbly. Stir in flours and zucchini. Add remaining ingredients and mix well. Knead dough on a floured surface for about 10 minutes. Let dough rise in a covered, buttered bowl for about 1 hour until doubled. Cut dough in half and form into 2 eight-inch loaves. Let rise in loaf pans until doubled, for about 45 minutes. Brush tops with water and bake in preheated 375 degrees F oven. After 3 minutes, brush tops again with water. Bake for 45 to 50 minutes. Cool for 10 minutes, then turn out of pans.