Pineapple/Nut Passover Sponge Cake

Preheat oven to 325F (160C).
Line the bottom of a 9 inch tube pan with a doughnut shaped piece of wax paper, notching around the cun center circle every inch.
Do not grease pan.
Sift first 4 ingredients.
into a bowl.
Set aside.
Separate eggs, droping 4 yolks into one mixing machine bowl and 10 whites into another.
Using whisk attachment, beat egg whites on medium-high speed until foamy.
Turn speed up to high.
Sprinkle in half the sugar and beat until stiff and glossy.
Set bowl with yolks on machine.
Beat until light.
Sprinkle in remaining sugar, zests and concentrate.
Beat on high speed until well blended.
Using a wooden spoon, stir about a 1/2 cup of beaten whites into yolks.
Then pour all of yolk mixture over beaten egg whites.
Fold in by hand in 12 sweeping strokes.
Sift dry ingredients again over all and continue folding for another 12 strokes.
Sprinkle and fold in nuts (another 12 strokes would suffice.)
Spoon into prepared pan, smoothing out top.
Run a blunt knife around sides to dispel any air bubbles.
Bake in Center section of oven for 55 minutes.
Top should be lightly browned and toothpick, when inserted, should come out clean.
Remove from oven and invert tube onto a 3-cup mason jar with a 1 1/2 inch neck, or any convenient holder that will fit the tube.
Cool for 1 1/2 hours.
Gently unmold.
Peel off wax paper.
When completely cooled, sift confectioner's sugar over.
Cut with sharp serrated knife, or pull apart servings with fork.