Research Reports No.26 （2020）

26－01

Chemical synthesis of existing food additives for internal reference Standards

Yosuke Demizu
Division of Organic Chemistry, National Institute of Health Sciences

For quality assurance of food additives, it is important to establish compositional standard tests by developing highly accurate analytical and evaluation methods. In this research, a new analytical method is established by developing a total synthetic route of some food additives for qualitative or quantitative standards,which are difficult to set content standards using conventional methods. The purpose of this research is developing the simple and accurate standard testing methodology. In this paper, the synthetic methods for crocin and carotenoid analogues are described.

26－02

Application of Antioxidant-Efficiency Assay-Method for Foods

Shin-ichi Nagaoka
Laboratory of Structural Chemistry, Department of Chemistry and Biology,
Faculty of Science and Graduate School of Science and Engineering, Ehime University

Tocopherols (vitamin E analogues), ascorbic acids (vitamin C analogues), tea catechins, carotenes, and so on, which are used as food additives for antioxidants, coloring agents, etc., prevent food degradation caused by oxidation due to free radicals, singlet oxygen, and so forth. Furthermore, they exist in various living tissues and scavenge free radicals, singlet oxygen, etc. to prevent aging. In the present study, we have attempted to apply practical antioxidant-efficiency assay-methods (Aroxyl Radical Absorption Capacity (ARAC),Singlet Oxygen Absorption Capacity (SOAC), Alfa-Tocopherol REcycling Capacity (ATREC) assay methods) to estimation of the antioxidant-efficiency for food additives and foods containing the additives.

26－03

Development of High-Throughput Analysis for Glycyrrhizin using Bioimprinting Technology ~Toward Breeding of Glycyrrhiza Meeting Standard of Japanese Pharmacopoeia~

Seiichi Sakamoto
Graduate School of Pharmaceutical Sciences, Kyushu University

Glycyrrhizin (GC) is triterpenoid saponin produced from Glycyrrhiza spp. (Leguminosae). GC has shown to possess hepatoprotective effect, anti-inflammatory effect, and anti-allergy effect. In the process of breeding valuable Glycyrrhiza spp., effective screening method for GC is required. In this study, we aim to develop high-throughput screening method using GC-recognized proteins prepared by bioimprinting technology.
Primarily, bioimprinting of horseradish peroxidase (HRP) and ovalbumin (OVA) was performed against free GC to prepare GC-biHRP and GC-biOVA, respectively. Subsequently, their recognizing activity against GC was evaluated by ELISA and an assay using conjugates between magnetic particles (MPs) and GC (MPs-GC).
The results indicated that GC-biHRP shown to recognize free GC with the detectable GC range of 0.78−3.125 μg/mL although recognizing activity was not observed for GC-biOVA, suggesting screening method for GC can be developed using GC-biHRP although further investigation is necessary to improve its quality in terms of sensitivity and accuracy.

26－04

Profiling of Components from Toxic Mushroom for the Obtainment of Chemical Standards

Koichi Inoue
College of Pharmaceutical Sciences, Ritsumeikan University

In this study, these chemical components from Tricholoma ustale and Hypholoma fasciculare were separated and purified by high-speed countercurrent chromatographic (HSCCC) technique. In previous reports,we showed that HSCCC is useful, efficient and low-priced method for the purification of various chemicals from natural components based on optimal two-solvent system. Our project produces the chemical data base of various toxic mushrooms in Japan. First step, the major toxic mushroom such as Omphalotus japonicus was applied by our approach. In this year's project, two mushroom samples from Japanese fields were applied. There, we offer to apply the HSCCC for preparative purification of various chemicals from mushroom extract. For two-solvent system, the optimal condition of hexane/ethyl acetate/methanol/water was optimized to obtain the pure chemicals from crude extract. This purified component was evaluated by liquid chromatography and tandem mass spectrometry. It is concluded that by requiring natural material and cost-effectiveness, our method represents a significant improvement over the complicated techniques for the purification of toxic chemicals from mushroom materials. This evidence showed that our approach would achieve the profiling of components from toxic mushroom for the obtainment of chemical standards.

26－05

Development of an analytical method for determination of non-volatile amines in fish and fish products using Py-Tag as a new derivatization reagent

Hiroshi Akiyama
Division of Foods, National Institute of Health Sciences

We investigated the analytical method of four nonvolatile amines (histamine, tyramine, cadaverine and phenylethylamine) in fish and fish products using a new derivatization reagent, 2,4,6-triethyl-3,5-dimethyl pyrylium trifluoromethanesulfonate (Py-Tag). The four nonvolatile amines were extracted from fish and fish products with trichloroacetic acid. The diluted extract was derivatized with Py-Tag and was then subjected to liquid chromatography-tandem mass spectrometry analysis. Here we describe the evaluation of the analytical method for determining the concentrations of the four nonvolatile amines in fish and fish products. The trueness and repeatability of the method were assessed by performing replicate analyses (n = 5) of five fish and fish products spiked with the four nonvolatile amines at three different concentration levels. The four nonvolatile amines found were 87% - 104% of the spiked concentrations and the relative standard deviations were ＜6.1%. A reference sample and quality control canned fish samples were analyzed by the method,and the concentrations of the histamine were within the acceptable concentrations. Finally, the develop method was used to determine concentrations of the four nonvolatile amines in 48 fish and fish products on the Japanese market. One whole dried sardine and three fish sauces had relatively high concentrations of histamine, tyramine and cadaverine. The developed method does not require cleanups using a solid phase extraction column or similar, and the derivatization reaction time was only 15 min. Overall, these results suggested the present method is reliable and suitable for rapid analysis in the four nonvolatile amines in fish and fish products.

26－06

ctual condition survey: Pharmaceutical education to quality assurance of foods and food additive

Yasuo Tsutsumi
Graduate school of pharmaceutical sciences, Osaka university

In this survey, it was found the present pharmaceutical education to quality assurance of foods and food additive education may be insufficient. Thus, educational improvement about quality assurance will be expected.

26－07

Development of breeding and production of theanine content using tea accessions

Hiroto Yamashita
United Graduate School of Agricultural Science, Gifu University, Yanagito, Gifu, Japan

Theanine is a specialized metabolite in tea plants and is important as a breeding trait. In this study, weaim to establish a basis for genomic breeding and the development of theanine-enhanced breeding of tea plants. First, we performed the ddRAD-seq analysis to prepare the SNPs information of tea accessions,which are the basis for genomic breeding. We evaluated the theanine content variation of tea leaves in tea accessions to find useful breeding materials. Then, Genome wide association study based on leaf theanine content was used to identify the causative genetic regions that were potential marker candidates. In addition,since the roots is theanine biosynthesis site, we also evaluated the theanine and precursor content of some genetic resources in roots using hydroponics to determine the genetic causes at the biosynthetic level. As a result, variations in theanine content in the roots were observed and amino acid polymorphisms in Theanine synthetases (TSs), a biosynthetic enzyme, were also identified. In the future, further analysis of the effects of amino acid polymorphisms in TSs will reveal the differences in the theanine biosynthetic capacity.

26－08

Analyzing the effect of food additives using a new monkey intestinal organoid culture

Ken Iwatsuki
Tokyo University of Agriculture, Department of Nutritional Science and Food Safety

Intestinal organoid culture system is now an area of intense study by physiologist, endocrinologist, molecular biologist and oncologist since organoids mimic native tissues that could not be replaced by other cell culture system. Using this system, we aim to understand how enteroendocrine cells in the gastrointestinal tracts function in response to influx of artificial sweeteners. We have recently generated a monkey intestinal organoids but having difficulties in maintaining the cells. In this study, we have examined whether bovine serum albumin (BSA) and Wnt3a-conditioned medium affect the growth of organoids. In addition, we have introduced Ngn3-EGFP transgenic mice and investigated whether intestinal organoids mimic their native tissues by immunohistochemistry and transcriptome analysis. Our results suggest that enteroendocrine cells within the intestinal organoids show similar protein and mRNA expression patterns as compared to their original tissues.
Now, we are on the progress of investigating effects of artificial sweeteners on both mouse and monkey derived intestinal organoids.

26－09

Effect of plant-derived anthocyanin dyes against intestinal tight-junctions

Hidekazu Hiroaki
Department of Basic Pharmaceutical Sciences, Graduate School of Pharmaceutical Sciences,Nagoya University

We assessed tight junction (TJ) modulating activities of total 15 flavonoids including 6 anthocyanidin derivatives against Madin Derby Canine Kidney (MDCK)-II cells. Immunofluorescent microscopy observation and Western blotting analysis of claudin-2 (CLD-2) were employed for the purpose. We extensively analyzed eight flavonoids classified into the three groups with the same aglycons, naringenin, hesperetin,and quercetin. In naringenin and quercetin series, the aglycons always showed stronger TJ-modulation, enhancement and decreasing, respectively, than that of the glycosides. The results suggested that the molecular targets may exist in cytosol rather than cell surfaces. We further discovered partial TJ-enhancing activity for cyanidin, delphinidin, luteolinidin, pelargonidin, peonidin, and didymin.

26－10

Development on a quantitative analysis method for alginate using a novel exo-type alginate lyase

Toshiyuki Shibata
Department of Life Sciences, Graduate School of Bioresources, Mie University Seaweed Biorefinery Research Center, Mie University

4-Deoxy-l-erythro-5-hexoseulose uronic acid (DEH) is a monosaccharide produced by the action of exotype alginate lyase (Exo-Aly) from alginate. DEH does not originate from glycuronan other than alginate,so it can be considered as the only compound that can be used as a standard for alginate. The purpose of this study is to develop a new quantitative method for alginate using DEH. The marine bacterium Falsirhodobacter sp. alg1 produces novel Exo-Aly (AlyFRB) and endo-type alginate lyase (AlyFRA) with strong alginate degrading property. As a result of enzymatic reaction by combining recombinant proteins of AlyFRB and AlyFRA, it was revealed that alginate was degraded into DEH. Furthermore, it was found that a mixture of alginate lyases was able to degrade alginate into DEH in the presence of thickening polysaccharides (pectin,λ-carrageenan, and sodium carboxymethylcellulose).

26－11

Action research for domestic production of safe and high quality saffron:application for agritherapy and contribution to local resident's health

Kayoko Takaura
The Museum of Osaka University

Saffron (defined as the stigma of Crocus sativus L.) is a highly economical farm product which has been used as medicine and spice. Most of them are imported from Iran and Spain but domestic products are also supplied in Japan. Its most famous production area is Taketa city (Oita, Japan) where "Taketa-Saffron Cultivation Method," the unique method to have saffron bloom indoors, but its production is decreasing drastically because of the aging of the producers and supply of cheaper imported products. We have investigated the history, methods and advantages of "Taketa-Saffron Cultivation Method" and compared the quality of domestic and imported products from the morphological point of view. This time, we have recorded temperature, humidity and luminous intensity and tried to quantify the environmental conditions of the traditional cultivation in order to record it and apply it for trial cultivation. Second, we focused on the new factor, aroma and compared the Saffron produced in Taketa and Iran. We measured compounds by GC-MS and tried the sensory test, then revealed that the aroma of those samples were obviously different. We also analyzed them by GC-olfactometry, which use the olfactory perception as a detector and investigated the compounds which cause the differences of the aroma.

26－12

Regulatory effects of sweeteners (glucose, sucralose) on fat taste perception and preference

Keiko Morimoto
Department of Health Sciences, Faculty of Human Life and Environment, Nara Women's University

In modern life, high-fat diets, which are risk factors for obesity or metabolic syndrome, are widespread. Research into the mechanisms of regulation of fat taste preference is important for human health. However,it is unclear whether dietary fat or sweeteners modulates fat taste perception and preference. We examined whether dietary fat or sweetener stimulation of lingual sensors affects fat preference in healthy young Japanese men and women. In addition, we investigated the effects of estradiol replacement on fat intake via plasma glucagon-like peptide-1 (GLP-1) in ovariectomized (OVX) rats. Young women participated in laboratory experiments three times in a random order in the menstrual, preovulatory, and mid-luteal phases during the menstrual cycle, and male subjects did so on an arbitrary day. Oleic acid detection thresholds determined using a three-alternative forced-choice methodology showed no gender difference, but fluctuated depending on menstrual cycle in in young women. The lingual stimulation with dietary fat tended to increase the fat preference score evaluated by choice of favorite cheese, but a sweetener stimulation did not affect it. Furthermore,there tended to be a correlation between the fat preference score and % energy intake from fat in a buffet-style lunch only in men. In addition, the effects of sex hormones on fat intake were dependent on sex or menstrual cycle. In OVX rats, estradiol suppressed fat intake by promoting lipid-induced plasma GLP-1 elevation in OVX rats. The present study suggests that there is a gender difference in the regulation of fat preference and fat intake which may be due to sex hormones.

26－13

Influences of non-caloric sweeteners in mammary development in pregnancy and milk production in lactation

Ken Kobayashi
Laboratory of Cell and Tissue Biology, Research Faculty of Agriculture, Hokkaido University

Breast milk contains appropriate and abundant nutrition for suckling infants. Appropriate breastfeeding can improve the health of the lactating mother and suckling baby. Recently, it has been reported that mammary epithelial cells (MECs) have a mechanism of sensing extracellular nutrient concentrations to regulate the milk production ability. However, it remains unclear whether MECs have a receptor for sensing extracellular sweeteners containing glucose and non-sugar sweeteners for regulating the milk production ability during lactation and mammary gland development during pregnancy. To address this issue, we prepared three types of culture models using mouse MECs. The results showed that a sweet receptor exists in the basolateral and apical membranes of MECs. A non-sugar sweetener sucralose, which was added in the lower chamber of the cell culture insert, caused downregulation of milk production in lactating MECs whereas sucralose in the lower chamber did not influence lactating MECs. Sucralose also influenced alveolar development of MEC-organoids cultured in Matrigel. In contrast, sucralose hardly influenced ductal branching of MEC-organoids. These results suggest that sucralose binds to MECs via the sweet receptor and regulates mammary alveolar development in late pregnancy and milk production during lactation.

26－14

Study of the signaling pathway initiating by ε-poly-L-lysine, a food additive, and its effect on actin cytoskeleton

Yoshiharu Inoue
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University

ε-Poly-L-lysine (ε-PL) exhibits antifungal activity against fungi including the budding yeast Saccharomyces cerevisiae. In this study, we investigated the signal transduction pathways involved in the antifungal activity of ε-PL and the effects of ε-PL on the actin cytoskeleton. Phosphorylation of Mpk1 occurred following the treatment with ε-PL. Since an Mkk1/Mkk2-deficient strain that is unable to phosphorylate Mpk1, and a Bck1-deficient strain that is unable to phosphorylate Mkk1/Mkk2 did not phosphorylate Mpk1, ε-PL was considered to activate the Mpk1-MAP kinase pathway in an Bck1-Mkk1/Mkk2-dependent manner. Signal influx into Pkc1, which phosphorylates Bck1, involves a system mediated by a low molecular weight G protein Rho1 and a system mediated by TOR complex 2 (TORC2). Phosphorylation of Mpk1 occurred following the treatment with ε-PL in a Pkc1 mutant (Pkc1_L54S-4C/S), which is unable to physically interact with Rho1. Furthermore, phosphorylation of Mpk1 was also caused by ε-PL treatment in a Pkc1_TASA mutant in which Thr1125 and Ser1143, both of which are the phosphorylation targets of TORC2, were replaced with Ala. These results suggest that ε-PL activates Pkc1 and/or Bck1 through the distinct route from the conventionally known pathway. In addition, we found that ε-PL treatment induced the depolarization of actin patches from the bud.

26－15

Anti-inflammation and chronic kidney disease prevention by food additive and edible carotenoids

Masashi Hosokawa
Faculty of Fisheries Sciences, Hokkaido University

Chronic kidney disease (CKD) is characterized by impaired kidney function with chronic inflammation and renal fibrosis, and leads to irreversible renal failure. CKD is a growing health problem and its prevention is an important subject worldwide. In this study, we paid attention food additive and edible carotenoids as the preventive compounds against CKD and investigated anti-inflammatory effects. β-Apo-8'-carotenal (5 μM) significantly suppressed IL-1β production in murine macrophage-like RAW264.7 cells activated by lipopolysaccharide. Lutein (1 μM) down-regulated proinflammatory cytokine IL-6 and chemokine IL-8 mRNA expression in human renal proximal tubular epithelial HK-2 cells stimulated by TNF-α. Furthermore, dietary fucoxanthin isolated from edible brown seaweeds markedly increased mRNA expression of HO-1, which is one of the most important antioxidant enzymes for endogenous oxidative stress, in the kidney in C57BL/6J mice. These results suggest that food additive and edible carotenoids such as β-apo-8'-carotenal, lutein and fucoxanthin show anti-inflammatory and protective effects on renal cells.

26－16

Evaluation of Nrf2-mediated antioxidant activity and developmental toxicity of natural food colorants using animal models

Makoto Kobayashi
Department of Molecular and Developmental Biology, Faculty of Medicine, University of Tsukuba

Recently, the antioxidant activity of natural food colorants has been discovered, and it is expected that the coloring of foods by them will lead to the prevention of lifestyle-related diseases. However, it is not clear which colorants have higher antioxidant activity in physiological conditions and what kinds of cellular mechanisms mediate their activity. The latter is predicted to be the Nrf2 pathway, a well-known master regulator of the antioxidant response. In this study, we utilized the model vertebrate zebrafish to evaluate in vivo antioxidant activity and toxicity of 14 natural food colorants. As a result, we found that cyanidin 3-glucoside and curcumin exerted significant in vivo antioxidant activity in an Nrf2-dependent manner.

26－17

Improvement of rheological properties of food ink for food 3D printer using polysaccharides toward better printing precision

Makoto Takemasa
Division of Life Science and Engineering, School of Science and Technology, Tokyo Denki University, Japan

Spatial resolution of the printed object was improved, in food 3D printing by changing the rheological properties of the food ink using food polysaccharides. When food ink made of rice powder was accumulated in 10 layers, by additive manufacturing style food 3D printer, the printed object could not keep the designed shape, due to the insufficient hardness of food ink especially for the bottom part of the accumulated layers. By addition of high molecular weight polysaccharides such as xanthan gum, the spatial resolution was largely improved, which is probably due to the increase of the apparent stiffness of the food ink. The intermolecular interactions, probably attractive forces such as hydrogen bonding among xanthan molecules induces weak gel network formation. In addition to the improvement of the rheological properties of the food ink, the average shear rate in the narrow needle in the extrusion process should also be optimized, which is required for the force limitation of the paste extruder.

26－18

Safety assessment of natural food additives using zebrafish larva

Katsuyoshi Matsunami
Department of Pharmacognosy, Graduate School of Biomedical and Health Sciences, Hiroshima University

In this study, we have demonstrated a possibility to evaluate and guarantee the biological safety of food additives by observing the phenotype of fertilized eggs of zebrafish. Furthermore, the chemical composition of okra and rice bran extracts, which are well known as food additives, were analyzed. The okra-derived compounds were found to be non-toxic to zebrafish. The safety evaluation method using zebrafish is useful for evaluating the biological safety of various compounds, including food additives. In addition, this experimental method can be implemented at a relatively low cost in most laboratories.

26－19

Bioavailability of ellagitannins with antiglycation properties

Toshio Niwa
Faculty of Health and Nutrition, Shubun University

We have isolated a metabolite of curcumin produced by human feces. From the analytical data, we determined the structure as 3-hydroxy-1,7-bis(3,4-dihydroxyphenyl)heptane (2). We herein synthesized the possible intermediates to determine the metabolic pathway and to isolate becteria that relate to curcumin metabolism. We synthesized tetrahydrocurcumin, hexahydrocurcumin, octahydrocurcumin, and demethyltetrahydrocurcumin. The bacteria named 1C produced 1,7-bis(3,4-dihydroxyphenyl)heptane from all synthetic curcumin derivatives. We then tried to isolate the bacteria which can produce hexahydrocurcumin from curcumin or which can metabolize demethyltetrahydrocurcumin. We then purified a colony that metabolizes demethyltetrahydrocurcumin.

26－20

Analysis of release of damage-associated molecular patterns involved in inflammation and allergy after intestinal epithelial damage by potassium aluminum sulphate and immunological safety evaluation

Ayako Wakabayashi
Nippon Medical School, Department of Microbiology and Immunology

Although it has been suggested that food additives may affect the induction and progression of allergies, the details have been unclear. Potassium alum (potassium aluminum sulphate) and ammonium alum (ammonium aluminum sulphate) are now widely used as food additives. However, these aluminum salts have strong immunostimulatory actions and have been developed as adjuvants for vaccines. In the present study, we examined whether aluminum-containing food additives such as potassium alum damage intestinal epithelial cells and promote the release of DAMPs such as HMGB1 and IL-33 from injured epithelial cells, and whether these released DAMPs activate immune cells such as dendritic cells and lymphocytes and are involved in the induction and progression of food allergy. Oral administration of both ovalbumin (OVA) and alum into mice induced hyperactivated immune responses such as antibody production against OVA and T cell proliferative responses, and it was suggested that their induction involved activation of dendritic cells and macrophages by DAMPs released from damaged intestinal epithelial cells. These results suggest that ingestion of aluminum-containing food additives such as potassium alum or ammonium alum may activate intestinal immune responses by promoting DAMP release from intestinal epithelial cells and contribute to the induction and progression of food allergy.

26－21

Verification of the importance of arginine intake and evaluation of pharmacokinetics and tissue distribution during anticancer drug treatment

Hitoshi Kotani
Shimane University Faculty of Medicine

Myeloid‐derived suppressor cells (MDSCs) play a crucial role in immunosuppression in tumor‐bearing hosts. MDSCs express arginase‐I; It suppress T‐cell function by reducing the levels of L‐arginine, respectively. We examined the anticancer effects of supplementation of L‐arginine in CT26 colon carcinoma‐bearing mice. Supplementation of L‐arginine showed a tendency to augment the efficacy of cyclophosphamide (CP). CP reduced the proportions of granulocytic MDSCs and increased the proportions of monocytic MDSCs in the spleen and tumor tissues of CT26‐bearing mice. L‐Arginine supplementation alone did not affect the MDSC subsets. CP treatment tended to reduce the plasma levels of L‐arginine in CT26‐bearing mice and significantly increased the number of tumor‐infiltrating CD8+ T cells. In addition, L‐arginine supplementation significantly increased the proportions of tumor peptide‐specific CD8+ T cells in draining lymph nodes. Importantly, additional supplementation of L‐arginine significantly increased the number of cured mice that were treated with CP and anti‐PD‐1 antibody. Totally, L‐arginine supplementation shows promise for boosting the therapeutic efficacy of chemoimmunotherapy.

26－22

Development of flavor evaluation technology mimicking mammalian olfactory response

Yosuke Fukutani
Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology

Flavors consist of combination of various odor molecules. It is thought that organisms utilize the responses of multiple olfactory receptors to identify complex odors. In this study, I analyzed the response changes of odorant receptors when stimulated with multiple odorant molecule mixtures using mammalian odorant receptor (ORs)-expressing cells. Although it was relatively easy to identify a single odorant molecule by using multiple ORs, the responsiveness and the sensitivity of discrimination of ORs was reduced against a mixture of two odorants. Differences in the responsiveness of the ORs were also observed between liquid-phase stimulation and vapor-phase stimulation using the mixture of odorants. Furthermore, when the commercial vanilla flavor was compared with vanillin, it was suggested that the response of the olfactory receptor to vanilla flavor was totally decreased, and that the masking effect between the contained molecules was large.

26－23

Development of subcritical fluid separation equipment for separation of flavors from natural resources at ambient temperatures

Masaki Ota
Environmentally-Benign Molecular Design and Synthesis, Ecomaterial Design and Process Engineering,
Department of Frontier Science for Advanced Environment, Graduate School of Environmental Studies,Tohoku University

Harmful organic solvents are sometimes used for general food processing. Especially, production of food additives needs organic solvents to improve solubility of an objective compound. However, the harmful organic solvents should not be hopefully used for the processing because of toxicity to the human body. In this work, green solvents that are harmless to the human body such as water, ethanol and carbon dioxide (CO₂) are utilized instead of harmful organic solvents. For the high-pressure technologies, we newly developed "subcritical fluid separation" according to the high-pressure vapor-liquid equilibria. With this separation technique, one of natural compounds, flavors,were separated from hops-extract. In this work, myrcene and linalool were treated as model compounds and the standard chemicals were used for measuring vapor-liquid distribution coefficients in CO₂-ethanol binary solvents.

26－24

Studies on selective adsorption mechanism on gold nanoparticles for removal of odor from long-aged sake

Haruno Murayama
Department of Chemistry, School of Science, Kyushu University

Silica-supported Au nanoparticles (Au/SiO₂) adsorbents selectively removed 1,3-dimethyltrisulfane (DMTS), which is responsible for an aged odor in Japanese sake. In this study, the adsorption efficiency of Au/SiO₂ was investigated by the competitive adsorption of DMTS and several kinds of aromatic components in Japanese sake, such as sotolon and furfural. When 60% of DMTS was adsorbed, only 17.2% of furfural was adsorbed, and then the concentration of other compounds was not reduced.
To practical use of the Au/SiO₂ adsorbents, two types of flow methods were examined. Au nanoparticles supported on silica with larger secondary particle size (≈ 1 mm) were also prepared. The flow methods achieved a higher rate of desulfurization than that of the batch method.

26－25

Studies on food hydrogels suitable for elderly people

Masayuki Hara
Graduate School of Science, Osaka Prefecture University, University Public Corporation Osaka

Rheology study on the food hydrogels is now becoming more important to prevent dysphagia in elderly society of developed countries including Japan. We prepared hydrogels containing a mixture of 1-16%(w/v) gelatin (Type A) and 1%(w/v) calcium alginate (GA-gels). GA-gel of higher gelatin content had transparent and faintly yellowish color while the one of lower gelatin content looked turbid and whitish. We autoclaved the GA-gels for 15 min at 121 °C as a heat-treatment. GA-gel of lower gelatin content became less transparent and more whitish. We carried out the compression test of the GA-gel disk and estimate the value of elastic modulus (Young's modulus) from the stress-strain curve. Young's modulus value was dependent on the gelatin content and was the highest with the 16%/1% GA-gel before the heat-treatment. However, the 4%/1% GA-gel showed the highest value of Young's modulus after the heat-treatment. The GA-gel is considered to have an inter-penetrating network structure. The GA-gel prepared by our method is easy to fabricate into any shape. The gels have some thermostability after its preparation and are useful as food hydrogels in the food industry.

26－26

Development of essential amino acid-supplemented soy protein drinks for elderly and ill persons

Eri Nakamura
Department of Food Science and Nutrition, School of Human Environmental Sciences,Mukogawa Women's University

Rheology study on the food hydrogels is now becoming more important to prevent dysphagia in elderly society of developed countries including Japan. We prepared hydrogels containing a mixture of 1-16%(w/v) gelatin (Type A) and 1%(w/v) calcium alginate (GA-gels). GA-gel of higher gelatin content had transparent and faintly yellowish color while the one of lower gelatin content looked turbid and whitish. We autoclaved the GA-gels for 15 min at 121 °C as a heat-treatment. GA-gel of lower gelatin content became less transparent and more whitish. We carried out the compression test of the GA-gel disk and estimate the value of elastic modulus (Young's modulus) from the stress-strain curve. Young's modulus value was dependent on the gelatin content and was the highest with the 16%/1% GA-gel before the heat-treatment. However, the 4%/1% GA-gel showed the highest value of Young's modulus after the heat-treatment. The GA-gel is considered to have an inter-penetrating network structure. The GA-gel prepared by our method is easy to fabricate into any shape. The gels have some thermostability after its preparation and are useful as food hydrogels in the food industry.

26－27

Study on New Taste Japanese Confectioneries mixed with Cellulose for Old-Age Diabetics

Toshio Kawano
Food Production Process Engineering, Faculty of Agriculture and Marine Science,Kochi University

For the purpose developing a new taste Japanese confectionary for Old-age diabetics, cellulose powder was partially applied in the trail obtained confectionaries as the alternative ingredient of wheat flour, and the quality evaluation was made for them. As a typical Japanese confectionary, 1) rice-flour dumpling, 2) steamed bean-jam bun packed in wheat dough, and 3) steamed bread mixed with soy powder and green tea powder, were adopted for the study. In the test of the thermal and moisture characteristics of material for confectionaries, ten kinds of basic powder materials including that used for the three confectionaries were evaluated in the view of physical properties. Also, exchanging wheat powder used for each confectionary partially with three type of cellulose powder different in its mean particle size, trial confectionaries were made according to the standard manufacturing process. For each trial confectionary, viscoelastic characteristics, surface color, expanding rate of dough in heating, and digestive efficiency were measured, and its different features from the standard without cellulose were analyzed.
As the results, all of the cellulose powder shows bigger water absorption rate than the other basic confectionary materials, the values ranged from 288% (in smallest particle size powder) up to 648% in the largest sample. This character of cellulose powder indicates that well consideration of adding water is needed before heating process.
Based on the results from viscoelastic characteristics measurements and digestive efficiency tests by chemically constructed gastric liquid, the exchange ratio of cellulose from 20% to 40% are recommended in case of making Japanese confectionaries for old-age diabetics.

26－28

Applying hydrophobin as an alternative protein for wheat gluten in food production
― hydrophobin for rice bread applied for foaming properties ―

Makoto Kanauchi
Miyagi University, Graduate School of Food, Agricultural and Environmental Sciences

Recently, many scholars are investigating rice bread production for preventing wheat allergies and for increasing food self-sufficiency in Japan. However, making soft and fluffy rice bread is difficult because rice flower contains no protein, such as gluten, to provide a structure supporting those physical properties. Hydrophobin is specifically examined herein for use as an alternative to gluten protein in wheat or barley for producing rice bread. This study specifically investigated the use of hydrophobin for rice bread production. It is expected to be applicable for gluten-free bread production in bakeries. Hydrophobin is a small molecular and hydrophobic protein producing mold or fungi. Samples used were from mushrooms: Enoki, Eryngii, Shiitake, Hiratake, and Crimini. Hydrophobin was extracted from the mushrooms using a surfactant solution. After surfactant removal, extracts from samples showed foaming ability. However, the amount of hydrophobic protein in solutions was unrelated to the foam height. Solutions with low hydrophobic protein concentrations exhibited a high degree of foaming ability. Furthermore, doughs containing hydrophobin extracted from the mushrooms rose during heating. Doughs containing hydrophobin extraction from Hiratake and Crimini mushrooms rose markedly higher than other doughs: 123%-125% compared to the control as without hydrophobin. Next, hydrophobin was extracted using an ethanol solution. Hydrophobin was extracted from Hiratake and Crimini mushrooms using 70% ethanol solution. Doughs containing hydrophobin extracted from mushrooms rose 157%-162% compared to the control. Results demonstrate that hydrophobin from mushrooms can be considered as an alternative protein of gluten for use in rice bread production; it exhibits potential for wider use in bakeries.