Carbohydrates in Farm and Marine Products

Abstract

We investigated the structural and functional properties of polysaccharides that constitute the cell walls of plant foods (including dietary fiber). We established methods to determine the fine structure and quantity of xyloglucans (XGs) and compared the structures of XGs from commonly consumed vegetables, fruits, and grains. The results demonstrated that XGs had different structures depending on the type, variety, and ripeness of the products. Glucuronoarabinoxylan (GAX) isolated from the primary cell walls of grasses contained ferulic acid esterified to its arabinose side-chains. Oligosaccharides originating from XGs and GAXs were found to have physiological functions. Water-insoluble cell walls (dietary fiber) had molecular sieving properties and delayed the diffusion rate of glucose in vitro.

Moreover, we explored potential added value of local agricultural, forestry, and fishery products, including unused resources, by analyzing their components, mainly polysaccharides. The following are the major findings of our research. (a) We developed a method to brew vinegar from apple pomace. This method involved treatment of the material with commercial bacterial enzymes to generate health-promoting oligosaccharides that remained in the final product, unutilized by yeast or acetic acid bacteria. (b) Using purple-black rice bran containing antioxidant anthocyanin pigments, we developed processed food that could serve as a rich source of health-promoting oligosaccharides, in addition to having high polyphenol (anthocyanin) and GABA contents. (c) We determined seasonal changes in the amounts of nutrients and health-promoting ingredients in Ecklonia stolonifera growing off the coast of Oma town, Aomori Prefecture. (d) We characterized the structure of proteoglycan (PG) present in salmon nasal cartilage. For the mass production of inexpensive PG-containing dietary ingredients, we established methods to defat (with water) and powder salmon nasal cartilage and to extract its PG fraction with hot water. We confirmed the safety of the resulting PG-containing product, demonstrated its skin anti-aging effects after oral administration, and developed a food item from the hot-water extract.