I chatted with an engineer one time who had built a wheat kernel sorting machine.
The wheat was sorted as it was loaded onto barges - so there was a LOT of wheat to sort one kernel at a time!

They used a color-discriminating electric eye thingy, and for the air jets they simply bolted steel plates on the front of loudspeakers with a tube leading from the plate to the sorting machine.
Transducers (coil-in-a-magnetic gap) are very fast and very controllable for air volume. And they are good for lots of cycles over their lifetime.

He said there were hundreds of lines running one kernel at time through the sorter.