I had a bad experience after trying the High5 samples given out a SiTS bitd™, involving dropping the bike and heading straight for a portaloo at the end of a lap…
Grab a jar of malt extract from your local healthfood shop and have a go at making your own; I did some research a couple of years ago and my gastrointestinal system is perfectly happy with the recipe I came up with.
I did try the rice cakes from Feed Zone Portables which work well, but don’t freeze all to well- a jersey pocket full of ricey mush is pretty suboptimal! Flapjack, cereal bars etc. work for me with Torq gel for an I’m-done-in-,-I-just-need-to-get-me-home type situation.