Hi Jerry,
If you search the 'Favourite Boilie' type threads on here, you will see that most of the guys use baits originally designed for carp. It is true that a few companies do bring out baits labeled as barbel specific (John Baker being a prime example), but it soon becomes obvious that there a very few, if any, differences between the two types.
When you consider the number of 'accidental' catches of bream, tench, roach...in fact pretty well any fish that swims, on boilies intended for carp, it would seem that any high quality, nutritionally ballanced boilie is a good bait...period! The fact that these same quality boilies are now used as the bait of choice by many top anglers for many species only goes to reinforce that fact.
So...accepting that fact, it becomes fairly easy to research the type of ingredients required, because most of the major boilie/bait manufacturers make at least some of these types of bait, and some publish a list of suggested recipes for quality baits. One such which I can recommend is C.C. Moores.
http://www.ccmoore.com/technical_information.php This link should lead you to their 'usefull information' page, and a search through the site will reveal actual recipes, and of course they sell all the ingredients you could want. There are other sites like this, and some of the other lads will perhaps supply links, or you could just Google it.
Oh...and no, before someone comments... I am not paid by C.C. Moores in any way, I am just trying to help by suggesting a good example of what is available.
Cheers, Dave.