Food safe basic polyelectrolytes?
Pectin is a heteropolysaccharide rich in galacturonic acid:



The carboxylic acid in galacturonic acid gives pectin the ionizable character. Pectin can react with bases to form carboxylate anions along the polysaccharide chain.

There exists a sugar-derivative and polysaccharide with opposite behavior - they react with acids to produce cations along the polysaccharide chain. The modified sugar is glucosamine, and the polysaccharides are chitin and chitosan(http://en.wikipedia.org/wiki/Chitosan). The amine ($\ce{NH2}$) group on glucosamine is basic and will react with acids to become cationic.



Glucosamine is used as a dietary supplement, and chitin and chitosan are found in various foods, like fungi and shellfish.