1. In large bowl, with fork beat undiluted orange-juice concentrate and egg whites until blended. In pie plate, mix sugar, cinnamon, allspice, and salt.
2. Preheat oven to 300°F. Stir cashews, pecans, and almonds into orange-juice mixture in bowl. With slotted spoon, remove nuts, about 1/2 cup at a time, to pie plate with sugar mixture; toss to coat well. Spread sugar-coated nuts on two 15 1/2 by 10 1/2" jelly-roll pans; bake 30 to 35 minutes, stirring occasionally, until nuts are golden.
3. Cool nuts in jelly-roll pans on wire racks 5 minutes; then with pancake turner, transfer to waxed paper to cool completely. Store sugared nuts in tightly covered container to use up within 2 weeks.