Combine crushed pineapple and unflavored gelatin in a saucepan.
Allow gelatin to soften for 5 minutes.
Bring to a boil, stirring to dissolve gelatin.
Remove from heat.
Stir in cold water.
Chill until mixture is the consistency of egg whites.
Stir in grated apple.
Transfer to four dessert dishes.
Chill until firm.