Welcome to the SeeMeCNC Community

I would like to print some food items. What are my options for printing mushes .

If i get bored of food printing then a setup that could be converted to print ceramics would also be nice.

I'm not aware of any injectors for printing unless you buy an entire printer (the pancake printer). But there are designs on Thingiveres to make a simple screw drive extruder that will print a range of pushes.

The Fab@Home project had a syringe extruder too. I merely got some commercial syringes and have been planning to design a mount and extruder drive to accommodate them. Haven't gotten around to that yet.

That is what i had in mind.

If the cold end is strong enough maybe a bowden setup can be used. I.e the filament does not go in to the hotend but pushes the plunger of the syringe.

There seem to be basically two approaches to this, either retrofit a syringe with a screw that will drive the plunger, or use a peristaltic pump. I think Richrap did some experiments in this space, so you might want to check out his blog.
Other sorts of pumps won't work because they pulse rather than giving a continuous stream.

I've also seen people on YouTube or somewhere online using an Archimedean screw to drive paste or concrete or something.