Message

  Macromolecular interactions among polysaccharides have been investigated based on physicochemical changes in aqueous sugar solutions. In many cases, sugar as a co-solute binds minimally to macromolecules; instead, it is preferentially hydrated by water molecules, resulting in increased macromolecular interactions. To elucidate the mechanism underlying this phenomenon, the interactions of various types of sugars with macromolecules was investigated, mainly by viscometric techniques.

Research Theme

  Physical aspects of the molecular interactions among macromolecules in sugar solutions were investigated, with a primary focus on polysaccharides in foods. Sugar as a co-solute binds minimally to polysaccharides, preferring instead to associate with water molecules. As a result, inter-molecular interactions occur. To resolve the mechanism underlying these interactions, we analyzed the relationship between the structures of sugars and their inter-molecular interactions, mainly by viscometry. Due to the complexity of and large number of compounds in typical foodstuffs, we used a model system to elucidate the molecular interactions.

  Generally, starchy foods, which have little nutritional worth without heat treatment, are degraded by enzymes at the end of the gelatinization process during the sol-gel transition of polysaccharides in water. Thus, non-gelatinized starchy products induce diarrhea. Due to its importance, the basic mechanism of gelatinization was recently rethought, resulting in measurement of the gelatinization process using general scientific equipment. Besides, we clarified the state of water involved in the gelatinization of starchy foods using the classical water sorption isotherm method. The resulting mathematical model represented the behavior of water vapor in terms of its absorption and adsorption on the surface of food.

  To sum up our research, the main title is “Analysis of the state of water involved in the function of food macromolecules.” With the exception of salts, which are minerals, all foodstuffs are made of or from living things; thus, this research may increase our knowledge of the regulation of biological functions. Therefore, our research titles are as follows:

1) Investigation of the inter-molecular interactions of food macromolecules in aqueous solutions;
2) Investigation of the gelatinization of starchy foods;
3) Investigation of water sorption behavior in foods; and
4) Investigation of the physical properties of baby food.

Publications

1. Yukinori SATO  2011 Analysis of Force on Plunger during Puncture Penetration for Texture Analysis of Baby Food International J Child Health and Human Dev, 4：183-189
2. Yukinori SATO, Osato MIYAWAKI  2012 Analysis of Apparent Viscosity of Aqueous Macromolecule Solutions Containing Sucrose Food Sci Technol Res, 18：563-570　
3. Yukinori SATO, Osato MIYAWAKI  2016 Analysis of hydration parameter for sugars determined from viscosity and its relationship with solution parameters Food Chem, 190：594-598
4. Yukinori SATO  2016 A modified American Association of Cereal Chemists method for compressive force value determination of white bread crumb firmness Food Sci Technol Res, 22：443-450