The influence of starch composition, morphology and structure on amylolysis

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My research program on the value-added processing of Canadian grains specifically focuses on grain carbohydrates such as starch and beta-glucan. I am interested in characterizing starch purified from various sources/genotypes in terms of their composition, structure and properties. In addition, currently my research is involved in how the chemical composition and structure of starch relates to its modification by chemicals and enzymes. The proposed research attempts to better understand the intricate nature of starch composition and structural inter-relationships that exist between starch components and how they influence the rate and extent of enzymatic digestibility. Highly processed foods contain many types of starch derivatives that often result from complete digestion of starch to dextrins/sugars, or by chemical modification to confer specific functional properties. On the other hand, rapidly growing trends in processed food have shifted toward starches that are resistant to digestion to assist in controlling sugar metabolism in diabetics. Recently, there has been increasing interest in starch-based renewable bio-fuel alternatives like ethanol, which require starch from agricultural crops to be hydrolyzed completely to glucose, which is then converted into ethanol by fermentation. This process is still unnecessarily expensive due to our lack of understanding and inability to control how the enzymes hydrolyze starch polymers of diverse structures. Regardless of whether starches are tailored to be resistant to digestion, as in the case with health foods, or to be readily digested, as required for ethanol production, the same research questions arise. This proposed research will study the major agricultural starch sources in parallel and within a controlled set of experiments. This sort of comprehensive study has not previously been performed. Using standardized procedures, the relationships between starch compositional, morphological and structural properties and the corresponding enzymatic digestibility will be systematically identified. In particular, determining the structural basis for the degree of susceptibility of starch to enzymatic hydrolysis is necessary to control the product outcome and to provide a defined target for genetic research.