We isolated and characterized several fucoidans from a kind of brown seaweeds, Laminaria angustata var. longissima., which has been eaten for about 300 years in Okinawa, Japan. The polysaccharides were extracted with 0.1mol/L HCl, and partially purified with cetylpyridinium chloride. The partially purified polysaccharides were fractionated by anion exchange chromatography, and four fractions (LA-1, LA-2, LA-3 and LA-4) were obtained. There was difference in the ratio of chemical composition of LA-1, LA-2, LA-3 and LA-4, but each fraction contained L-fucose residues and sulfate groups. Molecular weight of LA-1, LA-2, LA-3 and LA-4 were 27.7×10⁴, 1.0×10⁴, 0.8×10⁴ and 1.9×10⁴, respectively. The ¹H-NMR spectroscopy analysis of LA-2, which was the main fraction, and the desulfated LA-2 suggested that LA-2 consisted of the main chain of (1→3)-linked α-L-fucopyranosyl residues, a part of which had (1→2)-linked-α-L-fucopyranosyl residues at the C2 position, and these residues had sulfate group at the C4 position. It was suggested that the fractions LA-3 and LA-4 were the mixture of fucoidan and galactan sulfate.

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The effects of intake volume on bolus migration velocity were investigated by preparing model samples in which solid samples were dispersed in starch, guar gum, xanthan gum and water. The migration characteristics of the bolus in the pharyngeal region during deglutition were assessed and measured using a combination of the ultrasonic pulsed Doppler technique, swallowing contrast studies, sensory characteristics and mechanical characteristic values. The effects of increase and decrease of the bolus volume on mastication and deglutition were investigated. In both cases of 5 times and 30 times of mastication, the maximum migration velocity of the bolus water added and starch paste added samples tended to increase in accordance with increase of intake volume. These samples were easily affected by intake volume. However, guar gum added and xanthan gum paste added samples were not affected by the intake volume and maintained approximately the same migration velocity. Regarding the transit time, in the case of liquid-like boluses, transit time tended to lengthen as intake volume increased, whereas, in the case of viscous and solid-like boluses, they were hardly affected by increase of the intake volume and maintained approximately the same transit speed. These findings suggest that there is a high possibility that the effects of intake volume of solid dispersion pastes are associated with the mechanical characteristic values of added paste.

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A method to obtain clear binary images of bread crumb grain has been developed from the viewpoint of image synthesis, and named ‘Multiple Binarization Imaging Method (MBI).’ Nine thresholds were formally selected from a brightness histogram with 256 gray-levels. The object image was synthesized (logical add) from nine intermediate binary images with each threshold after eliminating unnecessary image element. The aim of this study is to examine the MBI method using bread-crumb simulated boards which had holes with constant diameter (3.0mm) and various depths (0.5-5.0mm), and those with constant depth (3.0mm) and various diameters (0.5-5.0mm). Brightness value of a hole is considered to be correlated to the depth of the hole. However, the hole diameter could not be identified from brightness value histogram with 256 gray-levels. Therefore, it was suggested that the number of thresholds which should be set did not depend on the hole diameter and the number of patterns of hole depths, but that it was derived from the fact that the gray image of air hole images had 10 classes. The MBI method yielded good and consistent binary images of crumb air bubbles of commercial white bread. Open-top type bread had coarser crumb structure with vertically orientated at the central area of the crumb. Pullman-type bread had finer porous structure without orientation at the central area of the crumb.

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In this study, we performed an interlaboratory study of the H-ORAC method (hydrophilic-oxygen radical absorbance capacity), which is an antioxidant potential measuring method using representative antioxidant components, on the basis of the guideline of AOAC International and investigated the accuracy. Eleven laboratories participated, and analyzed five representative antioxidative compounds ((+)-catechin, Trolox, trans-ferulic acid, hesperetin, and caffeic acid) in solution and in powder as blind duplicates. A statistical treatment revealed that the relative standard deviation of repeatability (RSD_r) of material solutions ranged from 5.9% to 13.2%, and from 5.4 to 10.4% in powder sample. The interlaboratory relative standard deviation of reproducibility (RSD_R) of material solutions or powders ranged from 16.2% to 61.4%, from 16.9% to 33.2%, respectively. The HorRat values of material solutions or powders calculated from the highest concentration of Trolox standard carve (50μM) ranged from 1.48 to 5.62 in solution example, from 1.54 to 3.03 in powder example, respectively. Thus, it is difficult to conclude that H-ORAC method used in the present interlaboratory study has acceptable precision. It is suggested that the individualities of plate readers cause the differences in the change of fluorescence intensity among the wells of the microplate, and that reduction of such differences induces improvement in the reproducibility.

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This study described the screening of α-amylase and α-glucosidase inhibitory activity in hot water and ethanol extracts of 195 species of wild/cultivated mushrooms. Tricholoma giganteum (Nioushimeji), Russula nigricans (Kurohatsu), Morchella esculenta (Amigasatake) and so on showed potent α-amylase inhibitory activity, and Boletus pseudocalopus (Niseashibeniiguchi), Cortinarius alboviolaceus (Usufujifuusentake), Cortinarius armillatus (Tsubafuusentake), Dictyophora indusiata (Kinugasatake) and so on showed potent α-glucosidase inhibitory activity. When they are compared using IC₅₀ data, α-glucosidase inhibition activity of these mushrooms was stronger than α-amylase inhibition activity of them. Active components of α-glucosidase inhibition activity were indentified as nojirimycin derivatives ; α-homonojirimycin and 7-o-β-D-glucopyranosyl-α-homonojirimycin, in four mushrooms such as B. pseudocalopus, C. armillatus, C. alboviolaceus, and D. indusiata using LC-TOFMS. Total nojirimycin derivative contents seemed to be correlated with α-glucosidase inhibitory activity. Therefore, it was suggested that the main active components of α-glucosidase inhibitory activity were nojirimycin derivatives regarding these four mushrooms.

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The reddish purple color of the abaxial side of Gynura bicolor DC. leaves is known to be anthocyanins. We previously isolated two novel poly-acylated anthocyanins, bicolnin and bicolmalonin from G. bicolor leaves and determined there chemical structures. In the present study, we evaluated the effects of light, heat, pH and metal ions on the stability of G. bicolor pigment to estimate its utility. Our evaluation results revealed that G. bicolor pigment showed significantly higher stability than such food colors prepared from red cabbage, red perilla and purple sweet potato. Furthermore, G. bicolor pigment didn’t show mutagenicity by the reverse mutation test. The application test of G. bicolor pigment as beverage also showed high stability. We concluded from these results that G. bicolor pigment is a useful novel natural food color having high stability and safety.

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[in Japanese]

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