Diabetes is a lifestyle disease, and its prevention and treatment are extremely important. Since Hoku243 presents fewer short-branched glucans and more long chains in the amylopectin starch, its starch is resistant to gelatinization and the boiled rice grains are non-sticky and brittle. The prevention of abrupt increases in postprandial blood glucose level (BGL) after consumption of Hoku243 (produced by high pressure treatment (HPT) after soaking in unsalted rice koji miso) was investigated in Sprague-Dawley (SD) rats. The BGL at 90 min and area under the curve (AUC) for 120 min after eating were significantly lower in SD rats fed Hoku243 than those in rats fed the control diet, consisting of Koshihikari rice (1% or 5% level). The addition of glucose, glutamic acid, and dietary fibers by soaking in an unsalted rice koji miso (unsalted miso) suspension made the boiled rice tasty and harder. After HPT, the texture of the boiled rice grains became harder, but sticky, which made the rice acceptable in terms of palatability and bio-functional in terms of digestion delay. It is now possible to produce palatable and bio-functional boiled rice grains by HPT and soaking in unsalted miso.
We achieved to synthesize a novel inclusion supramolecular polymer composed of continuum of amylose-poly(tetrahydrofuran) (PTHF) inclusion complexes by phosphorylase-catalyzed enzymatic polymerization using a maltoheptaose-PTHF conjugate according vine-twining polymerization manner. The 1H NMR and X-ray diffraction measurements indicated the presence of the inclusion complex structure in the product. The GPC peak of the amylose segment, which was dissociated by heating the vine-twining polymerization product, shifted to the lower molecular weight region, compared with that of the product, supporting the structure of the inclusion supramolecular polymer. The product by the G-1-P/G7-PTHF feed ratio = 100 was the supramolecular polymer composed of continuum of the amylose-PTHF inclusion complexes, whereas both inclusion complexes and amylose double helixes were present in the product by the G-1-P/G7-PTHF feed ratio over 200.
Conversion of fructose to 5-hydroxymethylfurfural (HMF) was conducted in an ionic liquid (IL), 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), with low-to-middle (≤ 0.03‒10%) water contents at 100°C with p-toluenesulfonic acid as a catalyst. When fructose was mixed with [BMIM]Cl to start the reaction, fructose dissolved much faster and more rapidly converted to HMF in [BMIM]Cl with a low water content than it did in that with a middle one, suggesting that the conversion rate greatly depended on the said water content. HMF was stable in pure [BMIM]Cl at 100°C, and there were few possibilities for its rehydration and decomposition to byproducts. Based on these results, we proposed an autocatalytic model of the reaction that considers the effects of water; the formation of HMF was certainly affected by the water produced during the conversion. The kinetic analysis based on this model well expressed the formation of HMF in the IL with a low water content.
A heterogalactan fraction, accounting for approximately 0.5% of the dry weight of the fruit body, was derived from a water-extracted polysaccharide fraction from antler-shaped Ganoderma lucidum. The heterogalactan fraction was characterized by sugar composition and sugar linkage composition analyses. The results suggest that the heterogalactan fraction consists of a fucomannogalactan (a linear (1→6)-D-galactan substituted at the O-2 position with non-reducing fucosyl and mannosyl residues), or a mixture of fucogalactan (a linear (1→6)-D-galactan substituted at the O-2 position with non-reducing fucosyl residues) and mannogalactan (a linear (1→6)-D-galactan substituted at the O-2 position with non-reducing mannosyl residues). The molecular weight of the heterogalactan fraction was estimated to be 1.0 × 104 by gel filtration on Sepharose CL-6B.
Chitin oligosaccharide deacetylase (COD) is an enzyme that generates β-N-acetyl-D-glucosaminyl-(1,4)-D-glucosamine from N,N′-diacetylchitobiose. COD has been found only in species of Vibrio bacteria. However, a homology search in the sequence databases revealed that Shewanella woodyi ATCC51908 also encodes a protein with sequence similarity to COD. Analysis of the deduced amino acid sequence of the S. woodyi COD (Sw-COD) confirmed that the protein contains the same motifs as CODs from Vibrio bacteria. The COD-encoding gene, which includes a signal sequence, was cloned from the chromosomal DNA of S. woodyi, the expression plasmid containing this gene was constructed, and then the plasmid was introduced into Escherichia coli HMS174(DE3) cells. The recombinant Sw-COD (Sw-rCOD) was produced in culture medium with the aid of the signal peptide and purified from culture supernatant. The properties of Sw-rCOD (substrate specificity, optimal pH, etc.) were similar to those of the CODs from Vibrio bacteria.
This work demonstrates the properties of calcium-fortified potato starch prepared by immersion in natural mineral water containing an extremely high level of calcium (468 ppm) and its food application. The calcium content of the fortified potato starch produced by use of the original mineral water was as high as 813 ppm, while calcium content of the control potato starch was 99 ppm. Rapid visco-analyzer data revealed that the calcium-fortified potato starch had a markedly lower peak viscosity and breakdown and a higher peak viscosity temperature than the control potato starch. Furthermore, calcium fortification caused a significant decrease in starch swelling power. Pound cakes made from the calcium-fortified potato starch and wheat flour blends tended to have a higher specific volume and sensory score of appearance than those made from the control potato starch and wheat flour blends. These findings suggest that the use of calcium-fortified potato starch is critical for making pound cakes with good quality in appearance.