entity export not serializing node
The entity_export function comes with the following caveat:


  Note: Currently, this only works for entity types provided with the entity CRUD API.


This means that if your entity type does not come with this, a call to entity_export() will return NULL.

This seems to be the case with node.

I am not sure, but I think the core team never got around to adding CRUD API to core entities.

If you inspect a node entity with dpm(), there is nothing. If you do:

 debug($node-&gt;delete, 'node-&gt;delete');


it prints NULL.