Training Treats Question

I doubt I'll get an answer here, but I figured it couldn't hurt and maybe it'll get a little activity back up in this community. Me and my partner just got two female rescue rats. They are a tad bit bitey and are working on training them out of it, as well as training them in various other ways. We were womdering what you guys use as a treat for training? We had heard brown rice makes a good one cause its tiny, but theres no good way to save the leftovers. We also heard Gerber puffs for babies, and got some but curious if there were better options yall are aware of.

Will post pics of them later. Their names are Soot and Sushi