Spread the wheatgerm and sesame seeds over a baking sheet and toast gently under a preheated grill, stirring a couple of times until the sesame seeds have begun to turn a golden brown. Remove from the grill and leave to cool.
Peel and slice the bananas. Remove the skin and core from the pineapple and chop the flesh. Put the banana and pineapple in a food processor or blender and process to a rough purée.
Add the apple juice and blend again to make a smooth juice. Add the yogurt and the cooled wheatgerm and sesame seeds. Blend again.
Pour the smoothie into a jug and serve immediately in glasses.