Decreased expression of fructosyltransferase genes in asparagus roots may contribute to efficient fructan degradation during asparagus spear harvesting.

Asparagus (Asparagus officinalis L.) accumulates inulin and inulin neoseries-type fructans in root, which are synthesized by three fructosyltransferases-sucrose:sucrose 1-fructosyltransferase (1-SST, EC 2.4.1.99), fructan:fructan 1-fructosyltransferase (1-FFT, EC 2.4.1.100), and fructan:fructan 6G-fructosyltransferase (6G-FFT, EC 2.4.1.243). Fructans in roots are considered as energy sources for emerging of spears, and it has been demonstrated that a gradual decrease in root fructan content occurs during the spear harvesting season (budding and shooting up period). However, the roles of certain three fructosyltransferases during the harvest season have not yet been elucidated. Here, we investigated the variation in enzymatic activities and gene expression levels of three fructosyltransferases and examined sugar contents in roots before and during the spear harvest period. Two cDNAs, aoft2 and aoft3, were isolated from the cDNA library of roots. The respective recombinant proteins (rAoFT2 and rAoFT3), produced by Pichia pastoris, were characterized: rAoFT2 showed 1-FFT activity (producing nystose from 1-kestose), whereas rAoFT3 showed 1-SST activity (producing 1-kestose from sucrose). These reaction profiles of recombinant proteins were similar to those of native enzymes purified previously. These results indicate that aoft2 and aoft3 encoding 1-FFT and 1-SST are involved in fructan synthesis in roots. A gradual downregulation of fructosyltransferase genes and activity of respective enzymes was observed in roots during the harvest period, which also coincided with the decrease in fructooligosaccharides and increase in fructose due to fructan exohydrolase activity. These findings suggest that downregulation of fructosyltransferases genes during harvest time may contribute to efficient degradation of fructan required for the emergence of spears.

Chemical Structure and Localization of Levan, the Predominant Fructan Type in Underground Systems of Gomphrena marginata (Amaranthaceae).

Gomphrena marginata Seub. (Amaranthaceae) is an endemic species from Brazilian campos rupestres with a fructan accumulating underground reserve system. Analyses of high performance anion exchange chromatography (HPAEC-PAD) revealed the presence of the soluble carbohydrates glucose, fructose, sucrose, 1-kestose, 6-kestose, nystose and fructans with degree of polymerization (DP) up to approximately 40 fructose units. Data of 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy, including Heteronuclear Single-Quantum Correlation (HSQC) and Heteronuclear Multiple-Bonds Correlation (HMBC) showed the presence of ß (2,6) linkages, characteristic of the linear molecule of levan-type fructan(2,6). These results confirmed previous studies suggesting that the reserve carbohydrate in the underground system of this species was levan-type fructans, similar to that of G. macrocephala. Structural analyses of the thickened underground system using light microscopy revealed a mixed origin system consisting mainly of a gemmiferous tuberous root with the upper region formed by short branched stems, both presenting vascular cylinders with unusual growth patterns. Fructan spherocrystals were visualized under polarized light and scanning electron microscopy (SEM) mostly in the cortex and vascular cylinder in both thickened stem and root. In addition to data reported in the literature concerning the occurrence of fructans in the Amaranthaceae, the results presented here suggest that fructans are a trait in this family while the levan-type fructan prevail in Gomphrena species.

Purification, characterization, and functional analysis of a novel 6G&1-FEH mainly hydrolyzing neokestose from asparagus.

Asparagus (Asparagus officinalis L.) accumulates inulin- and inulin neoseries-type fructans. Fructose released by the hydrolysis of fructans is an energy source for emerging asparagus spears. Plant fructans are hydrolyzed by fructan exohydrolases (FEHs), whose presence in asparagus has not yet been fully characterized. Here, we describe for the first time the purification and characterization of an FEH from asparagus, and the functional analysis of its gene. The purified enzyme was predicted to exist as a dimer (approximately 130 kDa) consisting of two polypeptides with a molecular mass of approximately 68 kDa. N-terminal sequences of the purified enzyme were matched with the amino acid sequences of aoeh4a and aoeh4b cDNAs isolated from asparagus (cv. Gijnlim and Taihouwase). Native enzymes obtained from asparagus roots and recombinant enzymes produced by Pichia pastoris showed fructan 1-exohydrolase (1-FEH) activity via the hydrolysis of inulin-type fructan. Unlike other 1-FEHs, these enzymes showed minimal hydrolysis of 1-kestose but efficiently hydrolyzed neokestose. Therefore, the enzyme was termed 6G&1-FEH. Gene expression studies in asparagus roots showed that aoeh4 increased during root storage at 2 °C and spear harvesting. These findings suggest that 6G&1-FEH may be involved in fructan hydrolysis in asparagus roots to provide an energy source for emerging asparagus spears.

Structural Analysis of Novel Low-Digestible Sucrose Isomers Synthesized from D-Glucose and D-Fructose by Thermal Treatment.

The synthesis of the saccharide ß-D-fructopyranosyl-(2→6)-D-glucopyranose, which was isolated from Super Ohtaka®, has recently been reported. During the synthesis of this saccharide, the formation of two novel saccharides from D-glucose and D-fructose was observed. The present study aimed to confirm the structures of the two disaccharides synthesized from D-glucose and D-fructose by thermal treatment. Furthermore, various properties of the saccharides were investigated. Both saccharides were isolated from the reaction mixture by carbon-Celite column chromatography and an HPLC system and were determined to be novel sucrose-isomers, ß-D-fructopyranosyl-(2↔1)-ß-D-glucopyranoside (1) and ß-D-fructofuranosyl-(2↔1)-ß-D-glucopyranoside (2), by MALDI-TOF MS and NMR analyses. Both saccharides showed low digestibility in vitro, and the sweetness of saccharide 2 was 0.45 times that of sucrose.

Structural Analysis of a Novel Oligosaccharide Isolated from Fermented Beverage of Plant Extracts.

A fermented beverage of plant extracts (Super Ohtaka®) was prepared from about 50 kinds of fruits and vegetables. This natural fermentation was performed by yeast (Zygosaccharomyces spp. and Pichia spp.) and lactic acid bacteria (Leuconostoc spp.) and resulted in the production of a novel fructopyranose-containing saccharide, which was subsequently isolated using carbon-Celite column chromatography and preparative-HPLC. The structure of the saccharide was determined using MALDI-TOF MS and NMR, and the saccharide was identified as ß-D-fructopyranosyl-(2→6)-ß-D-fructofuranosyl-(2↔1)-α-D-glucopyranoside. This is the first description of this novel saccharide and its isolation from a natural source.

Structural analysis of novel kestose isomers isolated from sugar beet molasses.

Eight kestose isomers were isolated from sugar beet molasses by carbon-Celite column chromatography and HPLC. GC-FID and GC-MS analyses of methyl derivatives, MALD-TOF-MS measurements and NMR spectra were used to confirm the structural characteristics of the isomers. The (1)H and (13)C NMR signals of each isomer saccharide were assigned using COSY, E-HSQC, HSQC-TOCSY, HMBC and H2BC techniques. These kestose isomers were identified as α-D-fructofuranosyl-(2- > 2)-α-D-glucopyranosyl-(1 < ->2)-ß-D-fructofuranoside, α-D-fructofuranosyl-(2- > 3)-ß-D-fructofuranosyl-(2 < ->1)-α-D-glucopyranoside, α-D-fructofuranosyl-(2- > 4)-ß-D-fructofuranosyl-(2 < ->1)-α-D-glucopyranoside, ß-D-fructofuranosyl-(2- > 4)-ß-D-fructofuranosyl-(2 < ->1)-α-D-glucopyranoside, ß-D-fructofuranosyl-(2- > 3)-α-D-glucopyranosyl-(1 < ->2)-ß-D-fructofuranoside, α-D-fructofuranosyl-(2- > 1)-ß-D-fructofuranosyl-(2 < ->1)-α-D-glucopyranoside, α-D-fructofuranosyl-(2- > 6)-α-D-glucopyranosyl-(1 < ->2)-ß-D-fructofuranoside, and α-D-fructofuranosyl-(2- > 6)-ß-D-fructofuranosyl-(2 < ->1)-α-D-glucopyranoside. The former five compounds are novel saccharides.

Structural confirmation of novel oligosaccharides isolated from sugar beet molasses.

Eleven oligosaccharides were isolated from sugar beet molasses using carbon-Celite column chromatography and HPLC. The constituent sugars and linkage positions were determined using methylation analysis, MALDI-TOF-MS, and NMR measurements. The configurations of isolated oligosaccharides were confirmed based on detailed NMR analysis. Based on our results, three of the 11 oligosaccharides were novel.

Structural confirmation of oligosaccharides newly isolated from sugar beet molasses.

BACKGROUND: Sugar beet molasses is a viscous by-product of the processing of sugar beets into sugar. The molasses is known to contain sucrose and raffinose, a typical trisaccharide, with a well-established structure. Although sugar beet molasses contains various other oligosaccharides as well, the structures of those oligosaccharides have not been examined in detail. The purpose of this study was isolation and structural confirmation of these other oligosaccharides found in sugar beet molasses. RESULTS: Four oligosaccharides were newly isolated from sugar beet molasses using high-performance liquid chromatography (HPLC) and carbon-Celite column chromatography. Structural confirmation of the saccharides was provided by methylation analysis, matrix-assisted laser desorption/ionaization time of flight mass spectrometry (MALDI-TOF-MS), and nuclear magnetic resonance (NMR) measurements. CONCLUSION: The following oligosaccharides were identified in sugar beet molasses: ß-D-galactopyranosyl-(1- > 6)-ß-D-fructofuranosyl-(2 <-> 1)-α-D-glucopyranoside (named ß-planteose), α-D-galactopyranosyl-(1- > 1)-ß-D-fructofuranosyl-(2 <-> 1)-α-D-glucopyranoside (named1-planteose), α-D-glucopyranosyl-(1- > 6)-α-D-glucopyranosyl-(1 <-> 2)-ß-D-fructofuranoside (theanderose), and ß-D-glucopyranosyl-(1- > 3)-α-D-glucopyranosyl-(1 <-> 2)-ß-D-fructofuranoside (laminaribiofructose). 1-planteose and laminaribiofructose were isolated from natural sources for the first time.

Isolation and structural confirmation of the oligosaccharides containing α-D-fructofuranoside linkages isolated from fermented beverage of plant extracts.

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 ß-D-fructopyranosyl-(2→6)-α-D-fructofuranosyl-(2↔1)-α-D-glucopyranoside.

Cloning and functional characterization of a fructan 1-exohydrolase (1-FEH) in edible burdock (Arctium lappa L.).

BACKGROUND: We have previously reported on the variation of total fructooligosaccharides (FOS), total inulooligosaccharides (IOS) and inulin in the roots of burdock stored at different temperatures. During storage at 0°C, an increase of FOS as a result of the hydrolysis of inulin was observed. Moreover, we suggested that an increase of IOS would likely be due to the synthesis of the IOS by fructosyltransfer from 1-kestose to accumulated fructose and elongated fructose oligomers which can act as acceptors for fructan:fructan 1-fructosyltransferase (1-FFT). However, enzymes such as inulinase or fructan 1-exohydorolase (1-FEH) involved in inulin degradation in burdock roots are still not known. Here, we report the isolation and functional analysis of a gene encoding burdock 1-FEH. RESULTS: A cDNA, named aleh1, was obtained by the RACE method following PCR with degenerate primers designed based on amino-acid sequences of FEHs from other plants. The aleh1 encoded a polypeptide of 581 amino acids. The relative molecular mass and isoelectric point (pI) of the deduced polypeptide were calculated to be 65,666 and 4.86. A recombinant protein of aleh1 was produced in Pichia pastoris, and was purified by ion exchange chromatography with DEAE-Sepharose CL-6B, hydrophobic chromatography with Toyopearl HW55S and gel filtration chromatography with Toyopearl HW55S. Purified recombinant protein showed hydrolyzing activity against ß-2, 1 type fructans such as 1-kestose, nystose, fructosylnystose and inulin. On the other hand, sucrose, neokestose, 6-kestose and high DP levan were poor substrates.The purified recombinant protein released fructose from sugars extracted from burdock roots. These results indicated that aleh1 encoded 1-FEH.

Synthesis of ß-D-fructopyranosyl-(2→6)-D-glucopyranose from D-glucose and D-fructose by a thermal treatment.

The synthesis is reported of ß-D-fructopyranosyl-(2→6)-D-glucopyranose that had previously been isolated from a fermented plant extract as a new saccharide. A disaccharide was predominately formed from an equal amount of D-glucose and D-fructose under melting conditions at 140 °C for 60 to 90 min. This saccharide was isolated from the reaction mixture by carbon-Celite column chromatography and preparative HPLC, and was confirmed to be ß-D-fructopyranosyl-(2→6)-D-glucopyranose by TOF-MS and NMR analyses.

Characterization of recombinant beta-fructofuranosidase from Bifidobacterium adolescentis G1.

BACKGROUND: We have previously reported on purification and characterization of beta-fructofuranosidase (beta-FFase) from Bifidobacterium adolescentis G1. This enzyme showed high activity of hydrolysis on fructo-oligosaccharides with a low degree of polymerization. Recently, genome sequences of B. longum NCC2705 and B. adolescentis ATCC 15703 were determined, and cscA gene in the both genome sequences encoding beta-FFase was predicted. Here, cloning of cscA gene encoding putative beta-FFase from B. adolescentis G1, its expression in E. coli and properties of the recombinant protein are described. RESULTS: Using the information of cscA gene from Bifidobacterium adolescentis ATCC 15703, cscA gene from B. adolescentis G1 was cloned and sequenced. The N-terminal amino acid sequence of purified beta-FFase from B. adolescentis G1 was identical to the deduced amino acid sequences of cscA gene from B. adolescentis G1. To confirm the translated product of the cscA gene, the recombinant protein was expressed in Escherichia coli. Molecular mass of the purified recombinant enzyme was estimated to be about 66,000 by SDS-PAGE and 60,300 by MALDI TOF-MS. The optimum pH of the enzyme was 5.7 and the enzyme was stable at pH 5.0-8.6. The thermostability of the enzyme was up to 50 degrees C. The K(m) (mM), Vmax (micromol/mg of protein/min), k0 (sec(-1)) and k0/K(m)(mM(-1) sec(-1)) for 1-kestose, neokestose, nystose, fructosylnystose, sucrose and inulin were 1.7, 107, 107.5, 63.2, and 1.7, 142, 142.7, 83.9, and 3.9, 152, 152.8, 39.2, and 2.2, 75, 75.4, 34.3, and 38, 79, 79.4, 2.1, and 25.9, 77, 77.4, 3.0, respectively. The hydrolytic activity was strongly inhibited by AgNO3, SDS, and HgCl2. CONCLUSION: The recombinant enzyme had similar specificity to the native enzyme, high affinity for 1-kestose, and low affinity for sucrose and inulin, although properties of the recombinant enzyme showed slight difference from those of the native one previously described.

Novel fructopyranose oligosaccharides isolated from fermented beverage of plant extract.

Four oligosaccharides containing a fructopyranosyl residue have been found from fermented beverage of plant extract and isolated from the beverage using carbon-Celite column chromatography and preparative high performance liquid chromatography. Structure confirmation of the saccharides was provided by methylation analysis, MALDI-TOF-MS and NMR measurements. These saccharides were identified as oligosaccharides of fructopyranoside series; beta-D-fructopyranosyl-(2-->6)-D-fructofuranose (1), beta-D-fructopyranosyl-(2-->1)-D-fructopyranose (2), beta-D-fructopyranosyl-(2-->1)-beta-D-fructofuranosyl-(2<-->1)-alpha-D-glucopyranoside (3), and beta-D-fructopyranosyl-(2-->6)-alpha-D-glucopyranosyl-(1<-->2)-beta-D-fructofuranoside (4). Saccharides 3 and 4 among novel saccharides 1, 3, and 4 were named 'pyrano-1-kestose (pyrano-isokestose)' and 'pyrano-neokestose', respectively.

Structural analysis of three novel trisaccharides isolated from the fermented beverage of plant extracts.

BACKGROUND: A fermented beverage of plant extracts was prepared from about fifty kinds of vegetables and fruits. Natural fermentation was carried out mainly by lactic acid bacteria (Leuconostoc spp.) and yeast (Zygosaccharomyces spp. and Pichia spp.). We have previously examined the preparation of novel four trisaccharides from the beverage: O-beta-D-fructopyranosyl-(2->6)-O-beta-D-glucopyranosyl-(1->3)-D-glucopyranose, O-beta-D-fructopyranosyl-(2->6)-O-[beta-D-glucopyranosyl-(1->3)]-D-glucopyranose, O-beta-D-glucopyranosyl-(1->1)-O-beta-D-fructofuranosyl-(2<->1)-alpha-D-glucopyranoside and O-beta-D-galactopyranosyl-(1->1)-O-beta-D-fructofuranosyl-(2<->1)- alpha-D-glucopyranoside. RESULTS: Three further novel oligosaccharides have been found from this beverage and isolated from the beverage using carbon-Celite column chromatography and preparative high performance liquid chromatography. Structural confirmation of the saccharides was provided by methylation analysis, MALDI-TOF-MS and NMR measurements. CONCLUSION: The following novel trisaccharides were identified: O-beta-D-fructofuranosyl-(2->1)-O-[beta-D-glucopyranosyl-(1->3)]-beta-D-glucopyranoside (named "3G-beta-D-glucopyranosyl beta, beta-isosucrose"), O-beta-D-glucopyranosyl-(1->2)-O-[beta-D-glucopyranosyl-(1->4)]-D-glucopyranose (4(1)-beta-D-glucopyranosyl sophorose) and O-beta-D-fructofuranosyl-(2->6)-O-beta-D-glucopyranosyl-(1->3)-D-glucopyranose (6(2)-beta-D-fructofuranosyl laminaribiose).

Molecular and biochemical identification of alien chromosome additions in shallot (Allium cepa L. Aggregatum group) carrying extra chromosome(s) of bunching onion (A. fistulosum L.).

To develop the bunching onion (Allium fistulosum L.; genomes, FF) chromosome-specific genetic markers for identifying extra chromosomes, eight shallot (A. cepa L. Aggregatum group; genomes, AA)--A. fistulosum monosomic addition plants (AA+nF) and 62 shallot--A. fistulosum single-alien deletion plants (AAF-nF) were analyzed by 23 different chromosome-specific genetic markers of shallot. The eight monosomic addition plants consisted of one AA+2F, two AA+6F, and five AA+8F. Of the 62 single-alien deletion plants, 60 could be identified as six different single-alien deletion lines (AAF-1F, -3F, -4F, -6F, -7F, and -8F) out of the eight possible types. Several single-alien deletion lines were classified on the basis of leaf and bulb characteristics. AAF-8F had the largest number of expanded leaves of five deletion plants. AAF-7F grew most vigorously, as expressed by its long leaf blade and biggest bulb size. AAF-4F had very small bulbs. AAF-7F and AAF-8F had different bulbs from those of shallot as well as other types of single-alien deletion lines in skin and outer scale color. Regarding the sugar content of the bulb tissues, the single-alien deletion lines showed higher fructan content than shallot. Moreover, shallot could not produce fructan with degree of polymerization (DP) 12 or higher, although the single-alien deletion lines showed DP 20 or higher. The content of S-alk(en)yl-L-cysteine sulfoxide (ACSO) in the single-alien deletion lines was significantly lower than that in shallot. These results indicated that chromosomes from A. fistulosum might carry anonymous factors to increase the highly polymerized fructan production and inhibit the synthesis of ACSO in shallot bulbs. Accordingly, alien chromosomes from A. fistulosum in shallot would contribute to modify the quality of shallot bulbs.

Biochemical and genetic analysis of carbohydrate accumulation in Allium cepa L.

Onion and shallot (Allium cepa L.) exhibit wide variation in bulb fructan content, and the Frc locus on chromosome 8 conditions much of this variation. To understand the biochemical basis of Frc, we conducted biochemical and genetic analyses of Allium fistulosum (FF)-shallot (A. cepa Aggregatum group) alien monosomic addition lines (AALs; FF+1A-FF+8A) and onion mapping populations. Sucrose and fructan levels in leaves of FF+2A were significantly lower than in FF throughout the year, and the springtime activity of acid invertase was also lower. FF+8A showed significantly higher winter sucrose accumulation and sucrose phosphate synthase (SPS) activity. Inbred high fructan (Frc_) lines from the 'W202Ax Texas Grano 438' onion population exhibited significantly higher sucrose levels prior to bulbing than low fructan (frcfrc) lines. Sucrose synthase (SuSy) activity in these lines was correlated with leaf hexose content but not with Frc phenotype. Markers for additional candidate genes for sucrose metabolism were obtained by cloning a major SPS expressed in onion leaf and exhaustively mining onion expressed sequence tag resources. SPS and SuSy loci were assigned to chromosome 8 and 6, respectively, using AALs and linkage mapping. Further loci were assigned, using AALs, to chromosomes 1 (sucrose phosphate phosphatase), 2 (SuSy and three invertases) and 8 (neutral invertase). The concordance between chromosome 8 localization of SPS and elevated leaf sucrose levels conditioned by high fructan alleles at the Frc locus in bulb onion or alien monosomic additions of chromosome 8 in A. fistulosum suggest that the Frc locus may condition variation in SPS activity.

Two novel oligosaccharides isolated from a beverage produced by fermentation of a plant extract.

An extract from 50 kinds of fruits and vegetables was fermented to produce a new beverage. Natural fermentation of the extract was carried out mainly by lactic acid bacteria (Leuconostoc spp.) and yeast (Zygosaccharomyces spp. and Pichia spp.). Two new saccharides were found in this fermented beverage. The saccharides were isolated using carbon-Celite column chromatography and preparative high performance liquid chromatography. Gas liquid chromatography analysis of methylated derivatives as well as MALDI-TOF MS and NMR measurements were used for structural confirmation. The (1)H and (13)C NMR signals of each saccharide were assigned using 2D-NMR including COSY, HSQC, HSQC-TOCSY, CH(2)-HSQC-TOCSY, and CT-HMBC experiments. The saccharides were identified as beta-D-fructopyranosyl-(2-->6)-beta-D-glucopyranosyl-(1-->3)-D-glucopyranose and beta-D-fructopyranosyl-(2-->6)-[beta-D-glucopyranosyl-(1-->3)]-D-glucopyranose.

Three novel oligosaccharides synthesized using Thermoanaerobacter brockii kojibiose phosphorylase.

BACKGROUND: Recently synthesized novel oligosaccharides have been produced primarily by hydrolases and glycosyltransferases, while phosphorylases have also been subject of few studies. Indeed, phosphorylases are expected to give good results via their reversible reaction. The purpose of this study was to synthesis other novel oligosaccharides using kojibiose phosphorylase. RESULTS: Three novel oligosaccharides were synthesized by glucosyltransfer from beta-D-glucose 1-phosphate (beta-D-G1P) to xylosylfructoside [O-alpha-D-xylopyranosyl-(1-->2)-beta-D-fructofuranoside] using Thermoanaerobacter brockii kojibiose phosphorylase. These oligosaccharides were isolated using carbon-Celite column chromatography and preparative high performance liquid chromatography. Gas liquid chromatography analysis of methyl derivatives, MALDI-TOF MS and NMR measurements were used for structural characterisation. The 1H and 13C NMR signals of each saccharide were assigned using 2D-NMR including COSY (correlated spectroscopy), HSQC (herteronuclear single quantum coherence), CH2-selected E-HSQC (CH2-selected Editing-HSQC), HSQC-TOCSY (HSQC-total correlation spectroscopy) and HMBC (heteronuclear multiple bond correlation). CONCLUSION: The structure of three synthesized saccharides were determined, and these oligosaccharides have been identified as O-alpha-D-glucopyranosyl-(1-->2)-O-alpha-D-xylopyranosyl-(1-->2)-beta-D-fructofuranoside (saccharide 1), O-alpha-D-glucopyranosyl-(1-->2)-O-alpha-D-glucopyranosyl-(1-->2)-O-alpha-D-xylopyranosyl-(1-->2)-beta-D-fructofuranoside (saccharide 2) and O-alpha-D-glucopyranosyl-(1-->[2-O-alpha-D-glucopyranosyl-1]2-->2)-O-alpha-D-xylopyranosyl-(1-->2)-beta-D-fructofuranoside (saccharide 3).

Structural analysis of a novel saccharide isolated from fermented beverage of plant extract.

Fermented beverage of plant extract was prepared from about 50 kinds of vegetables and fruits. Natural fermentation was carried out mainly by lactic acid bacteria (Leuconostoc spp.) and yeast (Zygosaccharomyces spp. and Pichia spp.). Three kinds of saccharides have been found in this beverage and produced by fermentation. The saccharides isolated from the beverage using carbon-Celite column chromatography and preparative HPLC, were identified as a new saccharide, beta-d-fructopyranosyl-(2-->6)-d-glucopyranose, laminaribiose and maltose by examination of constituted sugars, GLC and GC-MS analyses of methyl derivatives and MALDI-TOF-MS and NMR measurements of the saccharides.

Hydrolysis kinetic parameters of DP 6, 7, 8, and 9-12 fructooligosaccharides (FOS) of onion bulb tissues. effect of temperature and storage time.

The objective of this study was to report on the variation of DP 6 isomers (6b, 6c + 6d1 + 6d2), 7a, 8, and 9-12 fructooligosaccharides (FOS) and their hydrolysis parameters [percent hydrolysis, consumption rate, hydrolysis rate constant (k(obsd)), and half-life time (t(1/2))] in onion bulb tissues stored for 6 months at 10, 15, or 20 degrees C. The hydrolysis of DP 6 isomers, 7a, and 8 ranged from 74 to 85%, whereas that of DP 9-12 averaged 86%. The consumption rate of 6b, 6c + 6d1 + 6d2, 7a, 8, and -12 averaged 25, 58, 38, 26, and 48 microg/g of fresh weight per week, respectively. The k(obsd) showed large variation from 53 x 10(-3) week(-1) (lowest value) to 92 x 10(-3) week(-1) (highest value), whereas the half-life t(1/2) of the different FOS ranged between 7.5 and 13.1 weeks. DP 6b isomers increased during the first month, and then the content decreased sharply during the second month at 20 degrees C but remained stable during the last 4 months, whereas at 10 and 15 degrees C, 6b decreased progressively from the first to the six month. In contrast, DP 6c + 6d1 + 6d2 decreased abruptly within the first 3 months at 10, 15, and 20 degrees C; however, during the last 3 months they remained stable, ranging between 0.32 and 0.39. Variation of DP 7a, 8, and 9-12 FOS was close to that of DP 6 FOS isomers. DP 7a increased slightly during the first month, and afterward 7a started decreasing progressively during the last 5 months. DP 8 FOS showed a similar pattern independent of temperature regime: they increased slightly within the first month, but from the second month, DP 8 began decreasing progressively and continued decreasing to the sixth month. DP 9-12 FOS also varied similarly to DP 6c + 6d1 + 6d2. They decreased sharply within the first 2 months, and during the last 4 months, they continued to decrease slowly. Surprisingly, these variations occurred independently of temperature regimes and were affected only by storage duration. It was concluded that highly polymerized FOS are preferably hydrolyzed rather than low DP FOS isomers because they have a relatively high content of fructosyl end chains.