Preheat oven to 350 degrees F. Grease bottoms of two 9x5-inch inch loaf pans; set aside.
In a large bowl cream together softened butter and sugar. This is an important step you shouldn't skip, it will make the bread fluffier. Add eggs, one at a time, and mix well. Add lemon zest, coconut extract or emulsion, crushed/drained pineapple, rum and pineapple juice; set aside.
In a medium bowl combine all-purpose flour, Clabber Girl Baking Powder, Clabber Girl Baking Soda and salt. Add to butter mixture, 1/2 cup at a time, blending well after each addition.
Pour batter into prepared pans. Bake at 350 degrees F. for 45 minutes, or until loaves test done. (A toothpick inserted near center of loaf comes out clean.)
Prepare glaze while loaves are baking.
Glaze: In a small saucepan combine 3/4 c. sugar, 1/3 c. pineapple juice and 1/2 tsp. rum. Stir frequently with a whisk. Simmer on stove until sugar dissolves. Remove from heat.
When loaves come out of the oven, wait 5 minutes, then remove from pans onto a cooling rack with wax paper under the rack. Pour glaze over warm loaves as they are cooling on rack. The wax paper will collect any glaze that didn't soak in. You can use the extra glaze to re-coat the loaves a second or third time.