I know the pectins (fruit starch...) have been mentioned a fair bit... but many LHBS's carry pectinase which you'll probably want to use to some degree. Pectin is present in fresh fruit but it tends to be HEAVILY present in preserves, especially jellies, as that's what largely gives the jelly its consistency.
Too much starch in beer isn't at all desirable... it adds some character to certain beers but in fairly small amounts. Using pectinase will convert some of those fruit starches much in the same way that the mashing process, specifically the saccharification rest, or even using exogenous sources of amylase, converts grain starches into sugars.