Carbohydrate Research and Metabolomics: Current Projects
Metabolic Profiling StudiesMetabolite profiling is a strategy for screening the wide array of small molecules that can appear in a plant as response to a stimulus. Metabolites have roles in energy, redox control, defense, structural integrity and signaling. Therefore, the study of the metabolome can yield direct insight into many biological processes.The objective of metabolite profiling is to understand and predict the molecular behavior of living models. The information collected can then be explored utilizing data mining tools for modeling and simulation.
Polysaccharide Structure-Function Relationship
in Refrigerated Dough Quality
Refrigerated doughs account for greater than $1.7 billion per year in sales in the U.S., and they are one of the fastest growing segments of the ready-to-use grain-based industry. During storage, liquid separates from the dough, a phenomenon known as "dough syruping." It has been hypothesized that dough syruping is due to the action of enzymes present in the flour, which modify the water holding capacity of polysaccharides in the dough. Our recent research, however, has shown that interactions between macromolecular components present in dough, including polysaccharides and proteins, also affect dough syruping and the rheological properties of the final products. Since these interactions control the structure, texture and stability of refrigerated doughs, the proposed project is aimed to investigate polysaccharide-polysaccharide and protein-polysaccharide interactions in relation to their water holding capacity. Our results have shown that the decrease in water holding capacity is due to complex interactions involving non-starch polysaccharides, proteins, and starch. Rheological changes on stored refrigerated dough concomitant with these interactions also have been observed. Experiments have also shown that water holding capacity of refrigerated dough can be stabilized by addition of polysaccharides, which also affect the rheology of these systems.
Specific objectives of the proposed work include: (1) characterization of the structural (chemical) properties that affect dough syruping; (2) identification of rheological changes that occur during refrigeration, and as they relate to Arabinoxylans (AX) solubility and AX-AX, AX-starch and AX-protein interactions; and (3) development of formulations to prevent dough syruping and improve dough stability during storage.
Starch Digestibility and Chemistry
Starch has unique chemical and physical characteristics among other carbohydrates. It occurs naturally as distinct particles, called granules. Those granules are insoluble, relatively dense, and hydrate only slightly in room-temperature water. The other uniqueness of the starch is that most starch granules are a mixture of two sugar polymers: a highly branched polysaccharide named amylopectin, and a basically linear polysaccharide named amylose. The semi-crystalline properties of native starch are related to the short-chain fraction of amylopectin arranged as double helices and packed in small crystallites. Starch is the only polysaccharide that humasn can digest. Due to high rates of over-weight population (especially childhood obesity), there has been elevated attention to starch digestibility, which is governed by botanical source, structure of food matrix and fine structure of starch molecules. Physical and chemical starch modifications can alter the digestibility of starch. The starch is classified in three categories depending on the rate and extent of digestion as rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS). In one of our studies, we investigated the effect of cooking and chemical modification of physicochemical properties of starch including their digestibility. Our results showed tha, acetylation and oxidation can alter the digestion rate. However, there is more research needed to investigate the starch digestibility that is affected by food matrix, especially in whole wheat products.