Takuo Okita

Hypocholesterolemic effect of blue-green alga, ishikurage (Nostoc commune) in rats fed atherogenic diet

Blue-green alga,Nostoc commune is rich in dietary fiber. To examine the hypocholesterolemic effect, the alga or the dietary fibers were given to the rats fed cholesterol diet. Serum cholesterol elevation was significantly depressed in those rats. Cholesterol increased in the liver of rats given the alga and the fiber. The content of fecal cholesterol and bile acid unchanged. Of the dietary fibers, oxalate — oxalic acid soluble substance (OOSS) found abundant in the alga was most effective in lowering cholesterol in the serum. It seems to depress the elevation of LDL-cholesterol. The mechanism of hypocholesterolemic effect by OOSS remains to be unclear. This study indicated thatNostoc commune is expected to be a new dietary fiber source of possible importance in human nutrition.

Chemical composition, in vitro protein digestibility and in vitro available iron of blue green alga, Nostoc commune.

Blue-green alga,Nostoc commune, contained moderate amounts of protein and iron. Itsin vitro protein digestibility was 43–50%. The soluble and ionic iron from the alga was extractable to some extent at pH 1.5 but was not detectable at pH 8.0. The digestion by protease did not affect the iron detection. Heat processing at 100 and 120°C failed to increase the digestibility and the content of available iron. The dietary fiber in the alga may be responsible for low protein digestion and low iron availability.

A comparison of physical properties, oxalate-oxalic acid soluble substances, protein content, and in vitro protein digestibility of the blue-green algaNostoc commune Vauch. from the Philippines and Japan

The physical properties, amount of oxalate-oxalic acid soluble substances (OOSS), protein and in vitro protein digestibility ofNostoc commune from the Philippines and Japan were determined. The samples were the spherical type from the Philippines (PS), the dry field discoid type from the Philippines (PD), and the dry field discoid type from Japan (JD). The discoid types, PD and JD, regardless of origin showed higher settling volume in water (SV) and bulk density than PS. The OOSS values obtained for all samples were directly related to SV and bulk density. The WHC level was highest in PS. This desirable characteristic makes PS a technologically potential sample for large-scale food production applications in the future. Protein and in vitro protein digestibility varied significantly among all samples. In general, the algal samples examined posses desirable physical properties which are expected to be related to physiological functions.

Absorption of color additives and settling volume in water of blue-green alga, ishikurage (Nostoc commune).

The properties of ishikurage (Nostoc commune) and other algae were compared. Ishikurage and suizenji nori (Aphanothece sacrum) absorbed much more amaranth than others. They have a high settling volume (SV) in water. The high SV of ishikurage is attributable to its neutral detergent fiber (NDF). The acid detergent fiber (ADF) from the alga had a high amaranth absorption. However the absorption by the ADF did not explain the absorption by ishikurage.The results suggest that ishikurage may have a nutritional significance as a source of dietary fiber.