1. Heat oven to 350F. Grease an 8x4-inch loaf pan. In a bowl whisk together pastry flour, sugar substitute, soy flour, whole-wheat flour, baking powder, baking soda, and salt until combined. Stir in zucchini and rind.
2. In a small bowl whisk oil and eggs together. With a rubber spatula, combine egg and flour mixtures until flour is completely incorporated.
3. Spoon into prepared pan and bake 55 minutes or until a toothpick inserted in center comes out clean. Cool in pan on wire rack 10 minutes. Turn out onto rack to cool completely. Cun into 12 slices.