Jonny was a good kid who had to go bad in order to control the vamps at his disposal and counter the White God's influence.
Bigger capacity means more food stored and more than will quickly go bad should the unit fail.
It is likely to go bad before you get a chance to eat it all.
If it does not get eaten, just like any food, it can go bad.
As the above examples have demonstrated, plastic surgery can often go bad.