Even though chitin, chitosan and their derivatives have been considered as versatile biopolymers in food applications their potential uses as functional food ingredients have to be studied with broader emphasis. In that sense, research and development should have great potential in ®nding novel uses in product development, microbiology, edible ®lm industry, water purication, purication of waste discharge from food processing waste and nutritional aspects related to chitin, chitosan and their derivatives. Most physiological activities and functional properties of chitin and chitosan oligomers clearly depend upon their molecular weights and that a chain length of at least ®ve residues is required. These oligomers may be more advantageous than chitin and chitosan as polymers in the ®eld of food additives and nutraceuticals in
human health, because chitin and chitosan could not be degraded in the human intestine due to the absence of enzymes such as chitinase and chitosanase. In this con- text, chitin and chitosanmay behave as dietary ®bres which are excreted without any degradation in the intestine.
Furthermore, it is a current matter of discussion as to whether these biopolymers may have the potential to infuence physiological functions or metabolism in the human body. Therefore, a signi®cant increase in the number of scienti®c studies to obtain evidence to support any health or performance claim can be expected. In that sense, further detailed physiological and sensory
studies are required to determine the mechanisms of these effects and, ultimately, to come to a better understanding of how they may be manipulated in the creation of better quality foods.