Water-soluble dietary fiber provides numerous health benefits. A novel procedure to efficiently manufacture water-soluble indigestible polysaccharides was developed by heating glucose at 180 C in the presence of activated carbon. Aside from its ability to catalytically assist the polycondensation of saccharides, activated carbon provides the added benefits of being easily separable from the reactants and suppressing coloration of the product. Prior to purification, the indigestible fraction made up over 80% of the reaction mixture. After hydrolysis catalyzed by α-amylase and glucoamylase, and fractionation by ionexchange chromatography, a total of 99.7% dietary fiber content was attained. This indigestible fraction, termed resistant glucan, was only minimally degraded by upper digestive tract enzymes, similar to the digestibility of polydextrose. Structural analysis by methylation and NMR indicated that the resistant glucan formed a highly branched structure containing α-and β-1,2-, 1,3-, 1,4-, and 1,6-linkages. On an industrial scale, the resistant glucan was obtained from glucose syrup (DE 86) by heating with activated carbon, enzymatic hydrolysis, refining, fractionating, and drying. Our facile method is an efficient means to obtain water-soluble dietary fiber.
Selective and efficient: The copper(II)‐catalyzed selective monoarylation of vicinal diols with diaryliodonium triflates was successfully developed. In this catalytic process high chemoselectivity was achieved, even in the presence of a 1:1 mixture of the 1,2‐diol and the mono‐ol, and a wide range of substrates was tolerated, giving the monoarylated products in good to excellent yields (see scheme).
The catalytic deuterodechlorination of aryl/heteroaryl chlorides was developed with a palladium/unsymmetrical NHC system, and the precisely controlled introduction of deuterium into a variety of aryl/heteroaryl compounds was achieved with a high level of efficiency, selectivity, and deuteration degree. This method was also successfully applied to the transformation of bioactive agents even in a gram-scale synthesis. The crystal structure analysis of Pd-NHC complexes led to the observation of Pd-arene interaction.
Resistant glucan (RG) and hydrogenated resistant glucan (HRG) are newly developed non-digestible carbohydrate materials that decrease lifestyle-related diseases. The bioavailability of RG and HRG was investigated by in vitro experiments using human and rat small intestinal enzymes and by in vivo experiments using rats in the present study. Oligosaccharides, which are minor components of RG and HRG, were hydrolysed slightly by small intestinal enzymes of humans and rats, and the hydrolysing activity was slightly higher in rats than in humans. The amount of glucose released from HRG was greater than that from RG. However, the high-molecular-weight carbohydrates of the main components were hardly hydrolysed. Furthermore, neither RG nor HRG inhibited disaccharidase activity. When rats were raised on a diet containing 5 % of RG, HRG, resistant maltodextrin or fructo-oligosaccharide (FOS) for 4 weeks, all rats developed loose stools and did not recover during the experiment, except for the FOS group. Body weight gain was normal in all groups and was not significantly different compared with the control group. Caecal tissue and content weights were significantly increased by feeding RG or HRG, although other organ and tissue weights were not significantly different among the groups. In conclusion, RG and HRG consist of small amounts of glucose and digestible and non-digestible oligosaccharides, and large amounts of glucose polymers, which were hardly hydrolysed by α-amylase and small intestinal enzymes. RG and HRG, which were developed newly as dietary fibre materials, had no harmful effects on the growth and development of rats.Key words: Digestibility: Physical effects: New dietary fibre material: Resistant glucan: Hydrogenated resistant glucan Non-digestible carbohydrates such as dietary fibre and non-digestible oligosaccharides have health benefits and have been reported to prevent metabolic syndrome and lifestylerelated diseases (1)(2)(3) . However, the intake of non-digestible carbohydrate is gradually decreasing in developed countries, and the incidence of chronic diseases such as diabetes mellitus, heart disease and obesity is increasing (4) . To increase the intake of non-digestible carbohydrates, convenient food ingredients that can be easily added to meals and processed foods should be developed, contributing to preventing chronic diseases.Some non-digestible carbohydrate materials with distinctive properties have been developed and are widely used in meals and processed food. Polydextrose (PD), developed as a low-energy bulking carbohydrate material, is used in many beverages and low-energy foods (5,6) . Resistant maltodextrin (RMD) is another dietary fibre material used in many foods and was developed to suppress blood glucose elevation by carbohydrate foods and to improve defecation (7)(8)(9) . Fructooligosaccharide (FOS) is a non-digestible oligosaccharide present in many foods that was developed as a low-energy sweetener and non-cariogenic sweetener (9)(10)(11) . Non-digestible oligosaccharides ...
We previously developed an industrial production process for novel water-soluble indigestible polysaccharides (resistant glucan mixture, RGM). During the process, an anhydrosugar—levoglucosan —is formed as a by-product and needs to be removed to manufacture a complete non-calorie product. Here, we attempted to isolate thermophilic bacteria that utilize levoglucosan as a sole carbon source, to establish a removing process for levoglucosan at higher temperature. Approximately 800 natural samples were used to isolate levoglucosan-utilizing microorganisms. Interestingly, levoglucosan-utilizing microorganisms—most of which were filamentous fungi or yeasts—could be isolated from almost all samples at 25°C. We isolated three thermophilic bacteria that grew well on levoglucosan medium at 60°C. Two of them and the other were identified as Bacillus smithii and Parageobacillus thermoglucosidasius, respectively, by 16S rDNA sequence analysis. Using B. smithii S-2701M, which showed best growth on levoglucosan, glucose and levoglucosan in 5% (wt/vol) RGM were completely diminished at 50°C for 144 h. These bacteria are known to have a biotechnological potential, given that they can ferment a range of carbon sources. This is the first report in the utilization of levoglucosan by these thermophiles, suggesting that our results expand their biotechnological potential for the unutilized carbon resources.
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