In a small saucepan, mix gelatin with cold water. Let stand 1 minute; stir over medium heat until gelatin is completely dissolved, about 1 minute. Stir in honey and salt. Remove from heat and stir in bananas and lemon juice. Stif in yogurt. Pour into freezer tray. Freeze until firm. Turn frozen mixture into large bowl; add egg whites. Beat at high speed with electric mixer until smooth and fluffy, about 10 minutes. Return to pan and freeze.