- Molecular insight into regioselectivity of transfructosylation catalyzed by GH68 levansucrase and β-fructofuranosidase
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Glycoside hydrolase family 68 (GH68) enzymes catalyze β-fructosyltransfer from sucrose to another sucrose, the so-called transfructosylation. Although regioselectivity of transfructosylation is divergent in GH68 enzymes, there is insufficient information available on the structural factor(s) involved in the selectivity. Here, we found two GH68 enzymes, β-fructofuranosidase (FFZm) and levansucrase (LSZm), encoded tandemly in the genome of Zymomonas mobilis, displayed different selectivity: FFZm catalyzed the β-(2→1)-transfructosylation (1-TF), whereas LSZm did both of 1-TF and β-(2→6)-transfructosylation (6-TF). We identified His79FFZm and Ala343FFZm and their corresponding Asn84LSZm and Ser345LSZm respectively as the structural factors for those regioselectivities. LSZm with the respective substitution of FFZm-type His and Ala for its Asn84LSZm and Ser345LSZm (N84H/S345A-LSZm) lost 6-TF and enhanced 1-TF. Conversely, the LSZm-type replacement of His79FFZm and Ala343FFZm in FFZm (H79N/A343SFFZm) almost lost 1-TF and acquired 6-TF. H79N/A343S-FFZm exhibited the selectivity like LSZm but did not produce the β-(2→6)-fructoside-linked levan and/or long levanooligosaccharides that LSZm did. We assumed Phe189LSZm to be a responsible residue for the elongation of levan chain in LSZm and mutated the corresponding Leu187FFZm in FFZm to Phe. An H79N/L187F/A343S-FFZm produced a higher quantity of long levanooligosaccharides than H79N/A343S-FFZm (or H79NFFZm), although without levan formation, suggesting that LSZm has another structural factor for levan production. We also found that FFZm generated a sucrose analog, β-D-fructofuranosyl α-D-mannopyranoside, by β-fructosyltransfer to D-mannose and regarded His79FFZm and Ala343FFZm as key residues for this acceptor specificity. In summary, this study provides insight into the structural factors of regioselectivity and acceptor specificity in transfructosylation of GH68 enzymes.
- Kikuchi, Asako,Kimura, Atsuo,Lang, Weeranuch,Okuyama, Masayuki,Sadahiro, Juri,Serizawa, Ryo,Tagami, Takayoshi,Tanuma, Masanari
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- Inulinase immobilisation in PAA/PEG composite for efficient fructooligosaccharides production
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Inulinase was immobilised by entrapment method in polyacrylamide/polyethylene glycol composite and evaluated for its efficiency for short-chain fructooligosaccharides (3–6 degrees of polymerisation) production in batch hydrolysis system. Aqueous two-phase
- Dimitrovski, Darko,Krastanov, Albert,Temkov, Mishela,Velickova, Elena
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- Application of appel reaction to the primary alcohol groups of fructooligosaccharides: Synthesis of 6,6′,6′′-trihalogenated 1-kestose derivatives
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1-kestose (O-β-D-fructofuranosyl-(2→1)-β-D-fructofuranosyl-(2→1)-α-D-glucopyranoside) is a potential short chain fructooligosaccharide with an inulin-type skeleton. Halogenation of 1-kestose was conducted via the Appel reaction with the use of carbon tetrahalide (CBr4 or CCl4) and triphenylphosphine, which was then followed by conventional acetylation. The per-O-acetylated form of 6,6’,6’’-trihalogenated derivatives of 1-kestose were conveniently isolated. Further deprotection of the per-O-acetylated form resulted in 6-, 6’-, and 6’’-trihalogenated derivatives. The structure elucidation by one- and two-dimensional nuclear magnetic resonance established that halogenations are specific at the 6-, 6’-, and 6’’-position of 1-kestose primary alcohols.
- Tachrim, Zetryana Puteri,Nakamura, Tadashi,Sakihama, Yasuko,Hashidoko, Yasuyuki,Hashimoto, Makoto
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p. 341 - 348
(2019/01/03)
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- Separation and purification of fructo-oligosaccharide by high-speed counter-current chromatography coupled with precolumn derivatization
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High-speed counter-current chromatography (HSCCC) coupled with precolumn derivatization was developed for isolating and purifying fructo-oligosaccharides (FOSs). Firstly, the total FOSs were precolumn derivatized and then separated by high-speed counter-current chromatography (HSCCC) with two-phase solvent system petroleum ether-n-butanol-methanol-water (3:2:1:4, v/v). Secondly, the obtained compounds were deacetylated and the fructo-oligosaccharides (FOSs) with high purity were obtained. Their structures were identified by mass spectrometry (MS) and nuclear magnetic resonance (NMR). This research successfully established a novel strategy for separation and purification of FOS. There is no doubt that the application of the research will be beneficial for the quantitative and qualitative analysis of products containing FOSs.
- Duan, Wenjuan,Ji, Wenhua,Wei, Yuanan,Zhao, Ruixuan,Chen, Zijian,Geng, Yanling,Jing, Feng,Wang, Xiao
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- Enhancing fructooligosaccharides production by genetic improvement of the industrial fungus Aspergillus niger ATCC 20611
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Aspergillus niger ATCC20611 is one of the most potent filamentous fungi used commercially for production of fructooligosaccharides (FOS), which are prospective components of functional food by stimulating probiotic bacteria in the human gut. However, current strategies for improving FOS yield still rely on production process development. The genetic engineering approach hasn't been applied in industrial strains to increase FOS production level. Here, an optimized polyethylene glycol (PEG)-mediated protoplast transformation system was established in A. niger ATCC 20611 and used for further strain improvement. The pyrithiamine resistance gene (ptrA) was selected as a dominant marker and protoplasts were prepared with high concentration (up to 108?g?1 wet weight mycelium) by using mixed cell wall-lysing enzymes. The transformation frequency with ptrA can reach 30–50 transformants per μg of DNA. In addition, the efficiency of co-transformation with the EGFP reporter gene (egfp) was high (approx. 82%). Furthermore, an activity-improved variant of β-fructofuranosidase, FopA(A178P), was successfully overexpressed in A. niger ATCC 20611 by using the transformation system. The transformant, CM6, exhibited a 58% increase in specific β-fructofuranosidase activity (up to 507?U/g), compared to the parental strain (320?U/g), and effectively reduced the time needed for completion of FOS synthesis. These results illustrate the feasibility of strain improvement through genetic engineering for further enhancement of FOS production level.
- Zhang, Jing,Liu, Caixia,Xie, Yijia,Li, Ning,Ning, Zhanguo,Du, Na,Huang, Xirong,Zhong, Yaohua
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- Fructo-oligosaccharide synthesis by whole cells of Microbacterium paraoxydans
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The synthesis of fructo-oligosaccharides was carried out using whole cells of Microbacterium paraoxydans. Reactions were carried out using un-induced, inulin-induced and sucrose-induced cells displaying different amounts of invertase and inulinase activities out of which the best transfructosylation occurred using sucrose-induced cells displaying 12 I.U. invertase/0.75 I.U. inulinase activities. Using 40% w/v sucrose and in the sucrose-induced cells, a maximum fructo-oligosaccharide yield of 155 g/l (corresponding to product yield of 0.38 g/g initial substrate) was obtained. The major products synthesized were the tri-saccharide, 1-kestose [1F(1-β-D-fructofuranosyl)sucrose] and the tetrasaccharide, nystose [1F(1-β-D-fructofuranosyl)kestose]. A Box–Behnken design was used to optimize the factors affecting the fructo-oligosaccharide synthesis and these were at 31.5% sucrose, 10.96 I.U. invertase/0.69 I.U. inulinase and 14.32 h incubation time leading to an overall yield of 0.44 g/g initial substrate. The synthesized 1-kestose and nystose were purified to homogeneity by preparative TLC and structurally characterized by ESI-MS and 2D NMR.
- Ojha, Swati,Rana, Neetu,Mishra, Saroj
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p. 1245 - 1252
(2016/11/23)
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- Continuous production of fructooligosaccharides and invert sugar by chitosan immobilized enzymes: Comparison between in fluidized and packed bed reactors
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In this work, β-fructofuranosidase and β-fructosyltransferase were covalently immobilized on chitosan spheres, using glutaraldehyde as a coupling agent, in order to produce invert sugar and fructooligosaccharides (FOS). Maxinvert L was used to make β-fructofuranosidase biocatalyst yielding 7000 HU/g. A partial purified β-fructosyltransferase from Viscozyme L was used to prepare the other biocatalyst yielding 2100 TU/g. The production of invert sugar and FOS was evaluated using different continuous enzymatic reactors: two packed bed reactors (PBR) and two fluidized bed reactors (FBR). The invert sugar production achieved a yield of 98% (grams of product per grams of initial sucrose) in the PBR and 94% in the FBR, whereas FOS production achieved a yield of 59% in the PBR and 54% in the FBR. It was also observed in both cases that varying the flow rate it is possible to modulate the FOS composition in terms of nystose and kestose concentrations. The operational stability of FOS produced in the PBR was evaluated for 40 days showing no reductions in yields.
- Lorenzoni, André S.G.,Aydos, Luiza F.,Klein, Manuela P.,Ayub, Marco A.Z.,Rodrigues, Rafael C.,Hertz, Plinho F.
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- Optimization of levansucrase/endo-inulinase bi-enzymatic system for the production of fructooligosaccharides and oligolevans from sucrose
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A bi-enzymatic system based on the combined use of levansucrase (LS) from Bacillus amyloliquefaciens and endo-inulinase from Aspergillus niger in a one-step reaction was investigated for the synthesis of fructooligosaccharides (FOSs) and oligolevans using sucrose as the sole substrate. Sucrose concentration was the most important independent variable, whilst LS to endo-inulinase ratio exhibited significant effects on the end-product profiles. The interaction between sucrose concentration and reaction time exhibited significant effect on all responses. At the initial stage of time course, short chain FOSs (scFOSs, 1-kestose, nystose, 1F-fructosylnystose) were the major products, whilst 6-kestose, medium chain fructooligosaccharides (mcFOSs, levanohexaose, levanopentaose) and oligolevans became the dominant ones at the late stage. The optimal conditions leading to a high yield of scFOSs (1:1 ratio, 0.5 h, 0.6 M) were different from those resulting in a high yield of mcFOSs and oligolevans (1.85:1 ratio, 1.77 h, 0.6 M). The bi-enzymatic system has a great potential for the production of FOSs and oligolevans at a large scale because of its high yield (57-65%, w/w) and productivity (65.8-266.8 g/L h), and its uses of low temperature (35 °C) and low concentration of sucrose. To the best of our knowledge, this is the first study on the optimization of a LS/endo-inulinase bi-enzymatic system.
- Tian, Feng,Khodadadi, Maryam,Karboune, Salwa
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- Biomolecular characterization of the levansucrase of erwinia amylovora, a promising biocatalyst for the synthesis of fructooligosaccharides
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Erwinia amylovora is a plant pathogen that affects Rosaceae, such as apple and pear. In E. amylovora the fructans, produced by the action of a levansucrase (EaLsc), play a role in virulence and biofilm formation. Fructans are bioactive compounds, displaying health-promoting properties in their own right. Their use as food and feed supplements is increasing. In this study, we investigated the biomolecular properties of EaLsc using HPAEC-PAD, MALDI-TOF MS, and spectrophotometric assays. The enzyme, which was heterologously expressed in Escherichia coli in high yield, was shown to produce mainly fructooligosaccharides (FOSs) with a degree of polymerization between 3 and 6. The kinetic properties of EaLsc were similar to those of other phylogenetically related Gram-negative bacteria, but the good yield of FOSs, the product spectrum, and the straightforward production of the enzyme suggest that EaLsc is an interesting biocatalyst for future studies aimed at producing tailor-made fructans.
- Caputi, Lorenzo,Nepogodiev, Sergey A.,Malnoy, Mickael,Rejzek, Martin,Field, Robert A.,Benini, Stefano
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p. 12265 - 12273
(2014/01/06)
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- Screening of biocatalysts for transformation of sucrose to fructooligosaccharides
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Twenty microorganisms comprising of sixteen molds, two yeasts and two bacteria were evaluated for their ability to produce fructosyltransferase (FTase) and generate fructooligosaccharides (FOS) from sucrose. FTase production by these microorganisms was studied over a period of 120 h on medium containing 20% (w/v) sucrose as the sole carbon source. High FTase levels (35-31 U/ml) were observed in culture filtrates of Aspergillus flavus, Aspergillus niger, Aspergillus terreus and Penicillium islandicum. Higher concentrations of FOS were generated from 50% (w/v) sucrose using culture filtrates of A. flavus NFCCI 2364 (63.40%, w/w), A. niger SI 19 (54.94%, w/w), A. flavus NFCCI 2785 (44.61%, w/w), P. islandicum MTCC 4926 (43.56%, w/w), A. terreus NFCCI 2347 (24.17%, w/w) and Fusarium solani NFCCI 2315 (15.25%, w/w). Kestose, nystose and 1-fructofuranosyl nystose were the predominant oligosaccharides as revealed by HPLC analysis.
- Ganaie, Mohd Anis,Gupta, Uma Shanker,Kango, Naveen
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- Structural and kinetic insights reveal that the amino acid pair Gln-228/Asn-254 modulates the transfructosylating specificity of Schwanniomyces occidentalis β-fructofuranosidase, an enzyme that produces prebiotics
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Schwanniomyces occidentalis β-fructofuranosidase (Ffase) is a GH32 dimeric enzyme that releases fructose from the nonreducing end of various oligosaccharides and essential storage fructans such as inulin. It also catalyzes the transfer of a fructosyl unit to an acceptor producing 6-kestose and 1-kestose, prebiotics that stimulate the growth of bacteria beneficial for human health. We report here the crystal structure of inactivated Ffase complexed with fructosylnystose and inulin, which shows the intricate net of interactions keeping the substrate tightly bound at the active site. Up to five subsites were observed, the sugar unit located at subsite +3 being recognized by interaction with the β-sandwich domain of the adjacent sub-unit within the dimer. This explains the high activity observed against long substrates, giving the first experimental evidence of the direct role of a GH32 β-sandwich domain in substrate binding. Crucial residues were mutated and their hydrolase/transferase (H/T) activities were fully characterized, showing the involvement of the Gln-228/Asn-254 pair in modulating the H/T ratio and the type β(2-1)/β(2-6) linkage formation. We generated Ffase mutants with new transferase activity; among them, Q228V gives almost specifically 6-kestose, whereas N254T produces a broader spectrum product including also neokestose. A model for the mechanism of the Ffase transfructosylation reaction is proposed. The results contribute to an understanding of the molecular basis regulating specificity among GH-J clan members, which represent an interesting target for rational design of enzymes, showing redesigned activities to produce tailor-made fructooligosaccharides.
- Alvaro-Benito, Miguel,Sainz-Polo, M. Angela,Gonzalez-Perez, David,Gonzalez, Beatriz,Plou, Francisco J.,Fernandez-Lobato, Maria,Sanz-Aparicio, Julia
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experimental part
p. 19674 - 19686
(2012/08/14)
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- Synthesis of β-D-fructofuranosyl-(2→1)-2-acetamido-2-deoxy- α-D-glucopyranoside (N-acetylsucrosamine) using β-fructofuranosidase- containing Aspergillus oryzae mycelia as a whole-cell catalyst
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Using soft granules consisting of Celite 535 and dried Aspergillus oryzae NBRC100959 mycelia containing β-fructofuranosidase as a whole-cell catalyst, N-acetylsucrosamine [β-d-fructofuranosyl-(2→1)-2-acetamido- 2-deoxy-α-d-glucopyranoside] was produced from sucrose and 2-acetamido-2-deoxy-d-glucose by enzymatic transfructosylation. The isolated yield of N-acetylsucrosamine from the reaction mixture was 22.1% (from sucrose). The result of N-terminal amino acid sequence analysis indicated that the enzyme involved in the synthesis of N-acetylsucrosamine is a product from gene (NCBI accession number; NW-001884675, locus tag; AOR-1-1114084) encoding putative β-fructofuranosidase on chromosome 6 of strain NBRC100959. The N-acetylsucrosamine we produced is highly soluble in water and is more stable in acidic solution than sucrose. The disaccharide was also produced using dried mycelia prepared from another A. oryzae strains.
- Hirano, Takako,Wada, Toru,Iwai, Sumire,Sato, Hitoshi,Noda, Makoto,Juami, Mai,Nakamura, Masatoshi,Kumaki, Yasuko,Hakamata, Wataru,Nishio, Toshiyuki
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experimental part
p. 27 - 32
(2012/07/02)
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- Potential application of commercial enzyme preparations for industrial production of short-chain fructooligosaccharides
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Twenty-five commercial enzyme preparations for use in the food industry were assayed for transfructosylation activity. Three preparations showed high transfructosylation activity from sucrose as well as the ratio of transferase and hydrolase activities. Short-chain fructooligosaccharides (sc-FOS) were not hydrolyzed by the three enzyme preparations after a 12 h reaction time. At a 6 h reaction time, yield and volumetric productivity were in the range from 58.8 to 62.6% (g sc-FOS/100 g initial sucrose) and 52.5 to 55.9 g sc-FOS/L h, respectively. One enzyme preparation was then evaluated for sc-FOS synthesis. Thus, environmental factors influencing the reaction were studied on products. Total sc-FOS concentration was not affected by temperature, pH and enzyme concentration at the studied levels, but high concentrations of sucrose affected the sc-FOS formation. The results suggest that these enzyme preparations can be exploited as a source of food-grade fructosyltransferase, in addition to Pectinex Ultra SP-L.
- Vega-Paulino,Zuniga-Hansen
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experimental part
p. 44 - 51
(2012/04/11)
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- Isolation and structural confirmation of the oligosaccharides containing α-d-fructofuranoside linkages isolated from fermented beverage of plant extracts
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Fermented beverage of plant extracts was prepared from the extracts of approximately 50 types of vegetables and fruits. Natural fermentation was carried out mainly by lactic acid bacteria (Leuconostoc spp.) and yeast (Zygosaccharomyces spp. and Pichia spp.). Two oligosaccharides containing an α-fructofuranoside linkage were detected in this beverage and isolated using carbon-Celite column chromatography and preparative HPLC. The structural confirmation of the saccharides was determined by methylation analysis, MALDI-TOF-MS, and NMR measurements. These saccharides were identified as α-d-fructofuranosyl-(2→6)-d-glucopyranose, which was isolated from a natural source for the first time, and a novel saccharide β-d- fructopyranosyl-(2→6)-α-d-fructofuranosyl-(2?1) -α-d-glucopyranoside.
- Okada, Hideki,Fukushi, Eri,Yamamori, Akira,Kawazoe, Naoki,Onodera, Shuichi,Kawabata, Jun,Shiomi, Norio
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scheme or table
p. 2633 - 2637
(2012/01/02)
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- NMR structural study of fructans produced by Bacillus sp. 3B6, bacterium isolated in cloud water
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Bacillus sp. 3B6, bacterium isolated from cloud water, was incubated on sucrose for exopolysaccharide production. Dialysis of the obtained mixture (MWCO 500) afforded dialyzate (DIM) and retentate (RIM). Both were separated by size exclusion chromatography. RIM afforded eight fractions: levan exopolysaccharide (EPS), fructooligosaccharides (FOSs) of levan and inulin types with different degrees of polymerization (dp 2-7) and monosaccharides fructose:glucose = 9:1. Levan was composed of two components with molecular mass ~3500 and ~100 kDa in the ratio 2.3:1. Disaccharide fraction contained difructose anhydride DFA IV. 1-Kestose, 6-kestose, and neokestose were identified as trisaccharides in the ratio 2:1:3. Fractions with dp 4-7 were mixtures of FOSs of levan (2,6-βFruf) and inulin (1,2-βFruf) type. DIM separation afforded two dominant fractions: monosaccharides with fructose: glucose ratio 1:3; disaccharide fraction contained sucrose only. DIM trisaccharide fraction contained 1-kestose, 6-kestose, and neokestose in the ratio1.5:1:2, penta and hexasaccharide fractions contained FOSs of levan type (2,6-βFruf) containing α-glucose. In the pentasaccharide fraction also the presence of a homopentasaccharide composed of 2,6-linked βFruf units only was identified. Nystose, inulin (1,2-βFruf) type, was identified as DIM tetrasaccharide. Identification of levan 2,6-βFruf and inulin 1,2-βFruf type oligosaccharides in the incubation medium suggests both levansucrase and inulosucrase enzymes activity in Bacillus sp. 3B6.
- Matulová, Mária,Husárová, Slavomíra,Capek, Peter,Sancelme, Martine,Delort, Anne-Marie
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experimental part
p. 501 - 507
(2011/04/22)
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- PROCESS OF CITRIC OR PHOSPHORIC PARTIAL HYDROLYSIS OF INULIN FOR THE OBTENTION OF FRUCTOOLIGOSACCHARIDES - FOS
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In the technical field of Chemistry, encompassing products defined like FOS - fructooligosaccharides and applicable in food and or medical-pharmaceutical, veterinary and odontological industries, including the segment of supplements and functional foods, through the partial hydrolysis of inulins and similar fuctans till hydrossoluble FOS in the preferential range of DP - Degree of Polymerization from 2 to 18 or even more with reduced content of free fructose, using as catalysts for hydrolysis the citric and / or phosphoric acids as alternative to the classic hydrochloric or sulfuric acids and to the microbial enzymes, with the particularity that, through partial neutralization or simple dilution of the hydrolyzates, the catalysts now proposed, may either remain for the industrial and ulterior proposals or alternatively be removed by ion exchange resins or other means, being still possible that the citric or phosphoric acid may be conveniently diluted to the preferential range of pH 2.0 to 3.0 as moderate acidicity and the hydrolysis be carried out at moderate temperatures in the range from 75oC to 90oC in the range of preferential times from 5 to 30 minutes.
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Page/Page column 25-27
(2009/03/07)
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- Preparation of high-purity fructo-oligosaccharides by Aspergillus japonicus β-fructofuranosidase and successive cultivation with yeast
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The short-chain FOSs with high purity were prepared using a two-step strategy: Aspergillus japonicus extracellular β-fructofuranosidase- catalyzed synthesis of FOSs followed by cultivation with Pichia pastoris (P. pastoris). The higher FOSs content was obtained after 8 h under the catalysis of β-fructofuranosidase at pH 5.5 and 55°C. Successive P. pastoris cultivation exhausts almost all monosugars in 12 h at 30°C, which increases the purity of FOSs, and also recovers β-fructofuranosidase activity by ceasing the inhibition of glucose from catalysis of the enzyme, yielding more FOSs. Finally, the FOSs purity was increased from 56.55 to 84.45% (26.47% 1-kestose and 57.98% nystose).
- Yang, Ya-Lin,Wang, Jian-Hua,Teng, Da,Zhang, Fan
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experimental part
p. 2805 - 2809
(2010/05/02)
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- Physicochemical characterization of fructooligosaccharides and evaluation of their suitability as a potential sweetener for diabetics
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Fructooligosaccharides (FOSs) were prepared from sucrose using fungal fructosyl transferase (FTase) obtained from Aspergillus oryzae MTCC 5154. The resulting mixture consisted of glucose (28-30%), sucrose (18-20%) and fructooligosaccharides (50-54%) as indicated by HPLC analysis. Identification of oligomers present in the mixture of fructooligosaccharides was carried out using NMR spectroscopy and LC-MS. No compounds other than mono-, di-, tri-, tetra- and pentasaccharides were identified in the FOS mixture prepared using FTase. NMR and LC-MS spectra proved the absence of any toxic microbial metabolites of Aspergillus species in FOS thereby emphasizing its safe use as a food ingredient. Animal studies conducted on streptozotocin-induced diabetic rats suggested that the use of FOS as an alternative non-nutrient sweetener is without any adverse effects on various diabetes-related metabolic parameters. Despite the high free-sugar content associated with it, FOS did not further aggravate the hyperglycemia and glucosuria in diabetic animals, even at 10% levels. On the other hand, by virtue of its soluble fibre effect, it has even alleviated diabetic-related metabolic complications to a certain degree.
- Mabel,Sangeetha,Platel, Kalpana,Srinivasan,Prapulla
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- Kinetics of hydrolysis of fructooligosaccharides in mineral-buffered aqueous solutions: Influence of pH and temperature
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High-performance anion exchange chromatography coupled with a pulsed amperometric detection system (HPAEC-PAD) was used to evaluate the extent of chemical hydrolysis of three fructooligosaccharides (FOS) including 1-kestose (β-D-Fru-(2→1)2-α-D-glucopyranoside, GF2), nystose (β-D-Fru-(2→1)3-α-D-glucopyranoside, GF3), and fructofuranosylnystose (β-D-Fru-(2→1)4-α-D-glucopyranoside, GF4). A kinetic study was carried out at 80, 90, 100, 110, and 120 °C in aqueous solutions buffered at pH values of 4.0, 7.0, and 9.0. Under each experimental condition, the determination of the respective amounts of reactants and hydrolysis products showed that FOS hydrolysis obeyed pseudo-first-order kinetics as the extent of hydrolysis, which decreased at increasing pH values, increased with temperature. The three oligomers were found to be degraded mainly under acidic conditions, and at the highest temperature value (120 °C), a quick and complete acid degradation of each FOS was observed. Using the Arrhenius equation, rate constants, half-life values, and activation energies were calculated and compared with those obtained from sucrose under the same experimental conditions. It appeared that the hydrolysis of FOS took place much more easily at acidic pH than at neutral or basic pH values.
- L'Homme,Arbelot,Puigserver,Biagini, Anne
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p. 224 - 228
(2007/10/03)
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- Formation of trisaccharides (kestoses) by pyrolysis of sucrose
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Amorphous sucrose, containing citric acid as catalyst, undergoes thermolysis at 100° to yield fructofuranosyl cation and D-glucose. The cation reacts with unchanged sucrose to form all three of the known kestoses, and also their α-fructofuranosyl anomers. Two of the latter are resistant to invertase hydrolysis. A new fructosylglucose disaccharide is also formed. Amorphous sucrose, containing citric acid as catalyst, undergoes thermolysis at 100° to yield fructofuranosyl cation and D-glucose. The cation reacts with unchanged sucrose to form all three of the known kestoses, and also their α-fructofuranosyl anomers. Two of the latter are resistant to invertase hydrolysis. A new fructosylglucose disaccharide is also formed.
- Manley-Harris,Richards
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p. 101 - 113
(2007/10/02)
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