Usually it's about sorting. Take a lot of whatever (french fries, green beans, etc), accelerate them to something like 3 m/s, launch them off the end of a belt, scan them, looking for defects, and then use air jets to divert the defective items. Look on you tube for it. It's sort of mind boggling to see the scale at which french fries alone are produced. You see one line running at load, and then realize there are multiple lines in most plants, and there are hundreds of plants world wide. It's mind boggling.

The cooler machines were specialized for fries, they use a rotating knife drum above a belt to cut defect spots from fries.

I've not done that for 17 years now; the newer machines are that much cooler.