Blueberry Mandarin Orange Muffins

Name: Blueberry Mandarin Orange Muffins
Ingredients: For the muffins; 2 cups all purpose white flour; 1/2 cup white sugar; 1 tablespoon baking powder; 1 teaspoon salt; 1/2 cup walnut oil, almond oil or your choice; Zest from 3 Mandarin oranges; 1/2 cup fresh Mandarin orange juice (about 3 oranges); 1 1/4 teaspoons orange extract; 2 eggs; 1 cup fresh blueberries; For the streusel; 1/4 cup white sugar; 1/4 cup brown sugar; 1 tablespoon ground cinnamon; 1 1/2 tablespoons cocoa powder; 1 tablespoon mandarin orange zest