Preheat oven to 350°.
Combine first 4 ingredients in a large bowl; beat with a mixer at medium speed until well blended. Add banana and milk; beat well.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, wheat germ, baking powder, baking soda, and salt in a medium bowl, stirring well with a whisk. Add to sugar mixture; beat just until moist.
Spoon batter evenly into 12 muffin cups coated with cooking spray. Bake at 350° for 22 minutes or until muffins spring back when touched lightly in center. Cool in pan 5 minutes on a wire rack; remove from pan. Place muffins on wire rack.