Mix apples, apple juice concentrate, thickener and spice and stir until apples are well-coated, add lemon juice, if desired, to keep apples lighter colored. Taste 1 piece of apple to check the spice. Pour into the pastry lined pie pan and top with the second crust or pastry strips. Seal the edges and cut slits in the top crust to allow steam to escape. Bake at 425 degrees for 40 to 45 minutes, or until golden brown. Serve warm or cold.