2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

Evidence from feeding studies in human and animal model systems supports a role for resistant starch in reducing risk of colo-rectal cancer and maintaining bowel health. Resistant starch can be broadly defined as starch that escapes digestion during passage through the small intestine and is available for fermentation in the colon. The development of new sources of resistant starch from plants will require an understanding of the processes involved in starch biosynthesis and starch granule formation. The synthesis of starch in plants is catalysed by the concerted action of at least 4 classes of enzymes, ADPglucose pyrophosphorylase, starch synthase, branching enzyme and debranching enzyme. Typically, each of these enzyme activities is represented by several isoforms in starch synthesising tissues, and understanding the specific roles of each of these isoforms is essential to understanding the processes that synthesise starch and lead to the formation of starch granules. In this presentation, the state of knowledge of the starch biosynthesis process in higher plants will be reviewed and illustrated from our research on the molecular genetics and biochemistry of wheat and barley starch biosynthesis, and starch structure/function relationships. Approaches to manipulating the synthesis of starch and starch granule formation in order to develop starches with the potential to function as resistant starches in human foods will be discussed.