Structural confirmation of oligosaccharides newly isolated from sugar beet molasses

ABSTRACT: 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: beta-D-galactopyranosyl-(1- > 6)-beta-D-fructofuranosyl-(2 <-> 1)-alpha-D-glucopyranoside (named beta-planteose), alpha-D-galactopyranosyl-(1- > 1)-beta-D-fructofuranosyl-(2 <-> 1)-alpha-D-glucopyranoside (named1-planteose), alpha-D-glucopyranosyl-(1- > 6)-alpha-D-glucopyranosyl-(1 <-> 2)-beta-D-fructofuranoside (theanderose), and beta-D-glucopyranosyl-(1- > 3)-alpha-D-glucopyranosyl-(1 <-> 2)-beta-D-fructofuranoside (laminaribiofructose). 1-planteose and laminaribiofructose were isolated from natural sources for the first time.     

Automated determination of sugar in molasses

The importance of determining sugars in molasses is emphasized, and a short critical review of the methods available is presented. The difficulties and sources of errors in determining total sugar levels in molasses and sugar mixtures are discussed. A continuous automated procedure based on the hexacyanoferrate(III)/(II) redox reaction has been optimized by reducing the errors and interferences to a minimum. With this technique, sugar concentrations of 0–10 gl^-1 can be determined directly.     

Pectin substances of sugar beet pulp

Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, FAX (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 562–563, July–August, 1994.     

Enzymatic hydrolysis of ammonia-treated sugar beet pulp

Sugar beet pulp is a carbohydrate-rich coproduct generated by the table sugar industry. Beet pulp has shown promise as a feedstock for ethanol production using enzymesto hydroly zepolymeric carbohydrates and engineered bacteria to ferment sugars to ethanol. In this study, sugar beet pulp underwent an ammonia pressurization depressurization (APD) pretreatment in which the pulp was exploded by the sudden evaporation of ammonia in a reactor vessel. APD was found to substantially increase hydrolysis efficiency of the cellulose component, but when hemicellulose- and pectindegrading enzymes wereadded, treated pulp hydrolysis was no better than the untreated control.     

Evaluation of sugar sorption isotherm measurement by frontal analysis under industrial processing conditions

This paper evaluates frontal analysis for routine sugar isotherm measurements at industrial conditions, that is concentrations up to 400 kg/m3 and a temperature of 60 degrees C. Sugar isotherms for a gel type cation-exchange resin loaded with metal ions were measured in a HPLC setup equipped with a UV detector. It is shown experimentally that isotherms obtained with large concentration steps (step series method) underestimated the isotherm. The underestimation is larger for larger resin particle size. In contrast, isotherms obtained with small concentration steps (staircase method) yielded correct isotherms. The seldom-mentioned change of the sorbent volume during the course of an isotherm measurement is discussed. It is shown that shrinking of 4% cross-linked resin at high sugar concentration has a negligible effect on the isotherm. Furthermore, the isotherms obtained with staircase frontal analysis agreed very well with those obtained with the independent, though more laborious and time-consuming, adsorption-desorption method. Staircase frontal analysis is shown to be convenient and accurate and is therefore recommended for isotherm measurements covering large concentration ranges.     

Neutron activation analysis of final molasses from Cuban sugar industry

Thermal and epithermal non-destructive activation analyses have been performed on samples of final molasses from 14 different sugar factories, covering the most important regions in Cuba. From the first measurement after irradiation at the Triga Mark reactor (VTT), the concentration of more than 15 elements is reported. The almost constant elemental composition shows that they can be used equally for different purposes as animal foodstuff and for the manufacture of biotechnological products. This work is part of a research project developed in order to establish a complete characterization of Cuban sugar molasses.     

Physico-chemical characterization of a cellulosic fraction from sugar beet pulp

The residue of sugar beet pulp from which pectin and alkaline soluble polysaccharides have been removed by microwave assisted extraction or conventional heat was treated with sodium monochloroacetate under alkaline pH to convert the residual cellulose present to carboxy methyl cellulose (CMC). Weight average molar masses ranged from about 96 to 220 × 10³ Daltons, weight average intrinsic viscosity from 1.9 to 4.1 dL/g and degree of substitution from 1.38 to 0.59. HPSEC with online molar mass detectors and Atomic Force Microscopy revealed that CMC was comprised of aggregated linear moieties in contact with spherical bodies. The linear portion was a mixture of rods and segmented rods. Some of the rods had long branches.     

Spectrophotometric flow-injection determination of sucrose and total reducing sugar in sugar-cane juice and molasses

A flow-injection system with two sample carrier streams, one of them for on-line sucrose inversion, is proposed for the determination of sucrose and total reducing sugar. The method is based on the unselective oxidation of sugars by alkaline hexacyanoferrate(III) at ca. 95°C; the resulting hexacyanoferrate(II) is measured spectrophotometrically after addition of 1,10-phenanthroline and iron(III) sulphate. Two signals are recorded per cycle, reflecting the reducing sugar content of the sample before and after sucrose inversion. A debubber chamber removes the gases produced inside the heated reactors. Boiling water under reflux is used for heating. The effects of experimental variables and possible interferents are reported. The proposed system permits the analysis of about 40 samples per hour (80 measurements). Precise results (r.s.d.<1%) in agreement with those obtained with classical methods are achieved. Simplifications of the system are discussed.     

Improvement of paper strength via surface application of sugar beet pectin

The influence of surface-applied original and enzymatically-modified sugar beet pectin on strength properties of fluting, coating base paper, and core board was investigated. The effect was compared with the application of commercial strength-increasing agents. With increasing the polymer uptake, measured strength of paper increased. Original sugar beet pectin increased the strength properties of papers, at the same uptake of polymer, to a higher extent than oxidised potato starch or modified grain flour, while the effect of enzymatically-modified sugar beet pectin was the lowest. For the same increase of paper strength, a several times higher uptake of enzymatically-modified sugar beet pectin was required when compared with the original pectin, oxidised potato starch, or modified grain flour.     

Emulsifying properties and functional compositions of sugar beet pectins extracted under different conditions

Extraction conditions have important effects on the characteristics of sugar beet pectin (SBP). Response surface methodology (RSM) was used to study the impact of different extraction parameters on pectin yield, protein, ferulic acid, and galacturonic acid contents as well as on the emulsifying properties. Results indicated that pH was the main factor influencing pectin yield (ranging from 6.7 to 24.6%). Protein content varied from 0.5 to 6%, while ferulic acid content (ranging from 1.55 to 2.42%) was slightly influenced by the extraction conditions. Droplet sizes of the emulsions stabilized by different SBPs varied from 1.12 to 4.12 µm. Furthermore, according to the correlation analysis, protein content–pectin yield and ferulic acid–pectin yield demonstrated good correlations, respectively. Based on the present study, SBP with different functional components could be extracted as per relevant practical objectives.     

Complexation of bovine serum albumin and sugar beet pectin: Stabilising oil-in-water emulsions

In a previous study (Langmuir 28 (2012) 10164-10176.), we investigated the complexation of bovine serum albumin (BSA) with sugar beet pectin (SBP). A pH-composition phase diagram was established and structural transitions in relation to the phase diagram during complexation were identified. The present study examines the implications of these interactions on the emulsifying performance of BSA/SBP mixtures. Middle-chain triglycerides (MCTs) in water emulsions were prepared using conditions corresponding to different regions of the phase diagram. At high pHs and in the stable region of mixed individual soluble polymers where complexation is absent, there is no improved emulsifying performance, compared with the individual protein and polysaccharide. For these mixtures, the emulsion characteristics are controlled by the major component in the solutions, as determined by the competitive adsorption of the two components at the oil-water interface. At low pHs and low BSA/SBP ratios, and so mainly within the stable region of intramolecular soluble complexes, BSA/SBP mixtures greatly improve the stability of emulsions. Here, stabilisation is controlled by the cooperative adsorption of the two components at the oil-water interface. Through electrostatic complexation BSA promotes the adsorption of SBP on to interfaces to form a thick steric layer around emulsion droplets and thus providing better stability. At low pHs and high BSA/SBP ratios, that is, mainly within the unstable region of intermolecular insoluble complexes, emulsions prepared are extremely unstable due to bridging flocculation between emulsion droplets.     

Production and characterization of pullulan from beet molasses using a nonpigmented strain of Aureobasidium pullulans in batch culture

The production of pullulan from beet molasses by a pigment-free strain of Aureobasidium pullulans on shake-flask culture was investigated. Combined pretreatment of molasses with sulfuric acid and activated carbon to remove potential fermentation inhibitors present in molasses resulted in a maximum pullulan concentration of 24 g/L, a biomass dry wt of 14 g/L, a pullulan yield of 52.5%, and a sugar utilization of 92% with optimum fermentation conditions (initial sugar concentration of 50 g/L and initial pH of 7.0). The addition of other nutrients as carbon and nitrogen supplements (olive oil, ammonium sulfate, yeast extract) did not further improve the production of the exopolysaccharides. Structural characterization of the isolated polysaccharides from the fermentation broths by ¹³C-nuclear magnetic resonance spectroscopy and pullulanase digestion combined with size-exclusion chromatography confirmed the identity of pullulan and the homogeneity (>93% dry basis) of the elaborated polysaccharides by the microorganism. Using multiangle laser light scattering and refractive index detectors in conjunction with high-performance size-exclusion chromatography molecular size distributions and estimates of the molecular weight (M _w =2.1−4.1×10⁵), root mean square of the radius of gyration (R _g =30−38 nm), and polydispersity index (M _w /M _n =1.4−2.4) were obtained. The fermentation products of molasses pretreated with sulfuric acid and/or activated carbon were more homogeneous and free of contaminating proteins. In the concentration range of 2.8−10.0 (w/v), the solution’s rheologic behavior of the isolated pullulans was almost Newtonian (within 1 and 1200 s⁻¹ at 20°C); a slight shear thinning was observed at 10.0 (w/v) for the high molecular weight samples. Overall, beet molasses pretreated with sulfuric acid and activated carbon appears as an attractive fermentation medium for the production of pullulan by A. pullulans.     

The structure of the polyuronide of the leaves of the sugar beet

Summary The polygalacturonide of the pectin of sugar-beet leaves has been studied. It has a linear carbohydrate chain consisting of D-galacturonic acid residues in the pyranose form linked by -(14) bonds.M. V. Lomonosov Odessa Technological Institute of the Food Industry. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 321–324, May–June, 1975.     

Complexation of bovine serum albumin and sugar beet pectin: structural transitions and phase diagram

The complexation between bovine serum albumin (BSA) and sugar beet pectin (SBP) was studied in situ by coupling glucono-δ-lactone (GDL) induced acidification with dynamic light scattering and turbidity measurements. Individual measurements at specific pHs and mixing ratios were also carried out using zeta potentiometry, gel permeation chromatography-multiangle laser light scattering (GPC-MALLS), and isothermal titration calorimetry (ITC). These investigations together enabled the establishment of a phase diagram of BSA/SBP and the identification of the molecular events during protein/polysaccharide complexation in relation to the phase diagram, which showed five regions: (I) a stable region of mixed individual soluble polymers, (II) a stable region of intramolecular soluble complexes, (III) a quasi-stable region of intermolecular soluble complexes, (IV) an unstable region of intermolecular insoluble complexes, and (V) a second stable region of mixed individual soluble polymers, on lowering pH. We found for the first time that the complexation could take place well above the critical pH(c), the value that most previous studies had regarded as the onset occurrence of complexation. A model of structural transitions between the regions was proposed. The borderline between region II and region III represents the BSA/SBP stoichiometry for intramolecular soluble complex at a specific pH, while that between region III and region IV identifies the composition of the intermolecular insoluble complex. Also studied was the effect of NaCl and CaCl(2) on the phase diagram and structural transitions.     

Effect of pretreatment of molasses and posttreatment of fermented broth in industrial production of ethanol

The aim of preclarification is to minimize sludge going to yeast separators. This purpose is partially fulfilled. However, it has been measured during the plant trial runs that preclarification does not noticeably improve fermentation. The aim of postclarification is to minimize sludge going to distillation. This purpose is well served as noted from the fact that cycle run of distillation columns using postclarification is three times longer (9–12 mo) as compared to the normal one (3–4 mo).