DOCSLIB.ORG

Analysis of Sugars

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Analysis of Sugars Analysis of Sugars 1 Definition Nutritional labelling of food products requires listing of sugars content. Sugars means all mono-saccharides and di-saccharides present in food*. *Codex Guidelines on Nutrition Labelling, CAC/GL 2-1985 2 Mono- and di-saccharides HO OH OH OH OH OH OH O OH O O O etc HO HO OH HO OH HO OH HO OH HO OH OH Fructose Glucose Galactose Mannose OH O OH HO OH OH HO OH O HO HO OH O O HO HO O OH HO O O O OH HO OH OH OH O HO OH OH HO OH Sucrose Lactose Maltose OH OH O O HO O etc HO HO OH OH OH Cellobiose 3 Common mono- and di-saccharides HO OH OH OH OH O OH O O HO OH HO OH HO OH HO OH OH Fructose Glucose Galactose OH O OH HO OH OH HO OH O HO HO OH O O HO HO O OH HO O O O OH HO OH OH OH O HO OH OH HO OH Sucrose Lactose Maltose 4 Common mono- and di-saccharides HO OH OH OH OH O OH O O HO OH HO OH HO OH HO OH OH Fructose Glucose Galactose OH O OH HO OH OH HO OH O HO HO OH O O HO HO O OH HO O O O OH HO OH OH OH O HO OH OH HO OH Sucrose Lactose Maltose 5 Common sugars in foods Mono-saccharides: Fructose, glucose, galactose Di-saccharides: Lactose, maltose, sucrose 6 Properties of sugars (LC Analysis) OH Trimethylsilyl Primary amine chloride Glycosylamine O Methylsilyl HO ether (LC Analysis) HO OH (GC Analysis) OH Ac2O Acetate (GC Analysis) 7 Properties of sugars Water soluble. Low thermal stability. Do not have properties of fluorescence emission. 8 Sugar Analysis LC Methods with: Refractive Index Detector Evaporative Light Scattering Detector Pulsed Amperometric Detector 9 Current AOAC LC Methods 977.20 Honey Fructose, glucose, sucrose 980.13 Milk chocolate Fructose, glucose, lactose, maltose, sucrose 982.14 Presweetened cereals Glucose, fructose, sucrose, maltose 984.22 Purity of lactose Lactose 996.04 Cane & beet final Glucose, fructose, sucrose, molassess lactose 2000.17 Raw cane sugar Glucose, fructose 10 Current GB LC Method GB-T 22221-2008 食品中果糖、葡萄糖、蔗糖、麦芽糖、乳糖的测 定 高效液相色谱法 Determination of fructose, glucose, sucrose, maltose, lactose in foods – high performance liquid chromatography 11 Mono- and di-saccharides analysis Amine column Acetonitrile/water (80:20) Refractive index detector 2 mL/min at 30 oC 12 Mono- and di-saccharides analysis Amine column may not be able to resolve all the peaks. Alternative column may be used, e.g., Shodex sugar column. 13 Mono- and di-saccharides analysis Shodex column Water Refractive index detector 0.5 mL/min at 80 oC 14 Mono- and di-saccharides analysis 15 Analysis of reducing sugars AOAC methods: 920.183 Sugars (Reducing) in Honey 920.190 Sugars (Reducing) in Maple Products 945.66 Total Reducing Sugars etc. 16 Analysis of reducing sugars Fehling solution is used in the methods It relies on chemical reaction between the sugars and the Fehling solution. O O CuO +Cu2O R H R OH OH OH O OH HO HO HO OH HO O OH OH 17 Limitation of analyzing reducing sugar The best-known and most significant non-reducing sugar in foods is sucrose! (The most important OH O low molecular weight HO HO carbohydrate of animal diet). HO HO O O OH NOT appropriate for testing general food!! HO OH 18 Typical analysis SugarsSugars inin Preparation/Preparation/ LCLC samplesample CleanClean upup 19 Mono- and di-saccharides analysis Extract the sugars from sample using a mixture of ethanol and water 20 Mono- and di-saccharides analysis Centrifuge the mixture after the extraction 21 Mono- and di-saccharides analysis Clean up the extract by SPE 22 Mono- and di-saccharides analysis Clean up the extract by SPE 23 Mono- and di-saccharides analysis Analyse the extract using LC with refractive index detector 24 Proficiency test FAPAS LGC AOAC 25 CRM BCR NIST LGC 26 Points to note Sugar alcohols (polyols) are not “sugars” Not all monosaccharides and disaccharides are reducing sugars. Test method for reducing sugar may not be suitable for the analysis of sugars. 27 Points to note Definition of “0” Sugars ≤0.5 g/100 g Limit of detection of total sugars should be less than or equal to 0.5 g/100 g. 28 Thank You 29.
Load more

Recommended publications
  • Carbohydrates Carbohydrates Are One of the Main Macronutrients
    Carbohydrates Carbohydrates are one of the main macronutrients. They provide an essential source of energy. They are mainly found in plants, where they are manufactured by photosynthesis. Photosynthesis Photosynthesis is the process by which green plants use sunlight to make sugar (glucose) from carbon dioxide and water. How photosynthesis occurs Plant roots absorb water (H2O) from the soil. Leaves take in carbon dioxide (CO2) from the air. Chlorophyll (green pigment) in leaves absorbs energy from the sun. Result Glucose (sugar) (C6H12O6) is formed. Oxygen (O2) is released into the air. Equation for photosynthesis light energy 6CO2 + 6H2O — C6H12O6 + 6O2 chlorophyll Carbon + dioxide water — glucose + oxygen Elemental composition of carbohydrates Carbohydrates are made up of three elements: carbon (C), hydrogen (H) and oxygen (O). Monosaccharides Structure Chemical formula Examples Sources A simple sugar that C6H12O6 Glucose Fruit contains one simple Fructose Fruit and honey sugar unit. It is the Galactose Digested milk smallest unit of a carbohydrate. Chemical structure Disaccharides Structure Chemical formula Examples Sources Formed when two C12H22O11 Maltose Barley monosaccharides (glucose + glucose) Table sugar join, resulting in the Sucrose Milk loss of a water (H2O) (glucose + fructose) molecule Lactose (condensation (glucose + galactose) reaction). Chemical structure Polysaccharides Structure Chemical formula Examples Sources Formed when three (C6H10O5)n Starch Cereals and potatoes or more (n refers to the Pectin Fruit monosaccharides join number of Glycogen Meat together, resulting in monosaccharides Gums Plants and seaweed the loss of a water joined together) Cellulose Skins of fruit and (H2O) molecule with (dietary fibre) vegetables each new link Nuts (condensation reaction). Chains can be straight or branched.
    [Show full text]
  • A) and Co-Fermentation (B
    Simultaneous Co-Fermentation of Mixed Sugars: A Promising Strategy for Producing Cellulosic Biofuels and Chemicals Na Wei PI: Yong-Su Jin Energy Biosciences Institute /Institute for Genomic Biology University of Illinois at Urbana-Champaign Corn ethanol vs. Cellulosic ethanol Corn starch Cellulosic biomass Gelatinization Pretreatment + Cellulases Amylases Glucose + Xylose + Acetate Glucose + Fermentation inhibitors yeast yeast Ethanol + CO2 Ethanol + CO2 • Single sugar fermentation • Mixed sugar fermentation • No fermentation inhibitors • Fermentation inhibitors • Easy high loading • Difficulties in high loading 2 Saccharomyces cerevisiae: a workhorse strain for industrial ethanol production The most widely used yeast since ancient times in baking and brewing Osmotolerant and ethanol-tolerant Numerous genetic/genomic tools are available Overexpression / Knockout Expression of heterologous enzymes Cannot utilize xylose Not suitable for producing cellulosic biofuels 3 Basic strategy in metabolic engineering of xylose fermentation in S. cerevisiae Scheffersomyces stipitis Saccharomyces cerevisiae Xylose Xylose XYL1 Xylitol Xylitol XYL2 Xylulose Xylulose XYL3 X-5-P X-5-P PPP and Glycolysis PPP and Glycolysis Ethanol Ethanol . Natural xylose fermenting . High ethanol tolerance . Low ethanol tolerance . Amenable to metabolic engineering 4 Laboratory evolution of an engineered S. cerevisiae strain for further improvement DA24 n 16 Enrichment Single colony by serial culture isolation in 80 g/L of xylose Evaluation 5 Comparison of xylose fermentation capability between engineered S. cerevisiae and S. stipitis Engineered S. cerevisiae S. stipitis The engineered S. cerevisiae strain consumed xylose almost as fast as S. stipitis, the fastest xylose-fermenting yeast 6 Ha et al. PNAS, 108:504-509 Why we want to co-ferment cellobiose and xylose? Typical fermentation profile of glucose and xylose mixture Glucose Glycolysis Ethanol Pentose Phosphate Pathway CO2 Xylose 7 Engineered S.
    [Show full text]
  • Bioresources.Com
    PEER-REVIEWED ARTICLE bioresources.com ADSORPTION OF CELLOBIOSE-PENDANT POLYMERS TO A CELLULOSE MATRIX DETERMINED BY QUARTZ CRYSTAL MICROBALANCE ANALYSIS Shingo Yokota,† Takefumi Ohta, Takuya Kitaoka,* and Hiroyuki Wariishi Cellobiose-pendant polymers were synthesized by radical polymerization and their affinity for a cellulose matrix was investigated by quartz crystal microbalance (QCM). A 2-(methacryloyloxy)ethylureido cellobiose (MOU-Cel) macromer was synthesized by coupling cellobiosylamine with 2-(methacryloyloxy)ethyl isocyanate followed by polymerization in an aqueous radical reaction system. The interaction of the resulting poly(MOU-Cel) with a pure cellulose matrix in water was evaluated by QCM analysis. Poly(MOU-Cel) was strongly adsorbed to the cellulose substrate, whereas neither cellobiose nor MOU-Cel macromer exhibited an attractive interaction with cellulose. This specific interaction was not inhibited by the presence of ionic contaminants, suggesting that multiple cellobiopyranose moieties in each polymer molecule might cooperatively enhance its affinity for cellulose. Moderate insertion of acrylamide units into the polymer backbone improved the affinity for cellulose, possibly due to an increased mobility of sugar side chains. Polymers such as these, with a high affinity for cellulose, have potential applications for the surface functionalization of cellulose-based materials, including paper products. Keywords: Cellobiose; Cellulose; Sugar-pendant polymer; Non-electrostatic interaction; Quartz crystal microbalance Contact information: Department of Forest and Forest Products Sciences, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan; †Present address: Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan; *Corresponding author: [email protected] INTRODUCTION Cellulose is the most abundant, renewable carbohydrate resource and has been widely used as a raw material in a variety of applications (Klemm et al.
    [Show full text]
  • Cellobiose 2-Epimerase, Process for Producing
    (19) TZZ ¥ZZ_T (11) EP 2 395 080 B1 (12) EUROPEAN PATENT SPECIFICATION (45) Date of publication and mention (51) Int Cl.: of the grant of the patent: C12N 15/00 (2006.01) C12N 1/15 (2006.01) 06.08.2014 Bulletin 2014/32 C12N 1/19 (2006.01) C12N 1/21 (2006.01) C12N 5/10 (2006.01) C12N 9/90 (2006.01) (2006.01) (2006.01) (21) Application number: 10738433.1 C12N 15/09 C12P 19/00 (22) Date of filing: 25.01.2010 (86) International application number: PCT/JP2010/050928 (87) International publication number: WO 2010/090095 (12.08.2010 Gazette 2010/32) (54) CELLOBIOSE 2-EPIMERASE, PROCESS FOR PRODUCING SAME, AND USE OF SAME CELLOBIOSE 2-EPIMERASE, HERSTELLUNGSVERFAHREN DAFÜR UND VERWENDUNG CELLOBIOSE 2-ÉPIMÉRASE, PROCÉDÉ DE PRODUCTION DE CELLE-CI ET UTILISATION DE CELLE-CI (84) Designated Contracting States: (74) Representative: Daniels, Jeffrey Nicholas AT BE BG CH CY CZ DE DK EE ES FI FR GB GR Page White & Farrer HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL Bedford House PT RO SE SI SK SM TR John Street London WC1N 2BF (GB) (30) Priority: 05.02.2009 JP 2009025070 (56) References cited: (43) Date of publication of application: WO-A1-2008/062555 14.12.2011 Bulletin 2011/50 • PARK CHANG-SU ET AL: "Characterization of a (73) Proprietor: Hayashibara Co., Ltd. recombinant cellobiose 2-epimerase from Okayama-shi, Okayama (JP) Caldicellulosiruptor saccharolyticus and its application in the production of mannose from (72) Inventors: glucose.", APPLIED MICROBIOLOGY AND • WATANABE Hikaru BIOTECHNOLOGY DEC 2011 LNKD- PUBMED: Okayama-shi 21691788,vol.
    [Show full text]
  • Effect of Agronomic and Storage Practices on Raffinose, Reducing Sugar, and Amino Acid Content of Sugarbeet Varieties1
    Effect of Agronomic and Storage Practices on Raffinose, Reducing Sugar, and Amino Acid Content of Sugarbeet Varieties1 R. E. WYSE AND S. T. DEXTER2 Received fo,- /Jub lication July IO. 1970 Introduction The decrease in bagged sucrose per ton of beets during stor­ age results primarily from two factors. Sucrose is respired, evolv­ ing CO2 , The transformation of sucrose and other beet con­ stituents into raffinose, reducing sugars, amino acids, etc., re­ sults in an accumulation of non-sucrose solutes in the thin juice and corresponding increased sucrose losses into the molasses. Reducing sugars, raffinose and amino acids account for a major portion of the fluctuation in impurities during storage (Wyse et al.) 1970). The purpose of this study was to determine the in­ fluence of harvest date, nitrogen fertilization and storage tem­ perature on the content of these three impurities in several sugarbeet varieties. Reducing Sugars The predominant reducing sugars in the beet are glucose and fructose. Free galactose and arabinose are found only in trace amounts (Silin, 1964). Reducing sugars are presumably destroy­ ed during lime defecation and occur in very small amounts in beet molasses (McGinnis, 1951; Silin, 1964). In this process the reducing sugars are degTaded to acids (lactic, formic, acetic, sac­ charinic) (Carruthers et al.) 1959) which must be neutralized by the addition of sodium carbonate before evaporation to re­ duce soluble lime salts and to prevent sucrose inversiop (Silin, 1964; McGinnis, 1951). As a result of the addition of sodium carbonate, molasses quantity and purity are increased resulting in increased sucrose losses (Si Jin, 1%4).
    [Show full text]
  • Rapid Method for the Estimation of Total Free Monosaccharide Content of Corn Stover Hydrolysate Using HPAE-PAD
    Application Note 225 Note Application Rapid Method for the Estimation of Total Free Monosaccharide Content of Corn Stover Hydrolysate Using HPAE-PAD Valoran Hanko and Jeff Rohrer Thermo Fisher Scientific, Sunnyvale, CA, USA Introduction The Thermo Scientific™ Dionex™ CarboPac™ PA1 Compositional carbohydrate analysis of biocrop feedstock anion-exchange column rapidly elutes corn stover is essential to the efficient production of cellulosic carbohydrates, resolving the monosacccharides from the ethanol.1 Corn stover is the leaf, husk, stalk, and cob unretained and undetected noncarbohydrate components remaining in the field after harvest and makes up about of acid-hydrolyzed corn stover. Under these conditions, half the yield of a crop of corn. It can also contain weeds disaccharides and trisaccharides are also resolved, with a and grasses collected during the harvest of corn stover. total elution time less than 10 min. Thus, the sum of all Along with other lignocellulosic biomass, corn stover the carbohydrate peaks is a useful measure of the energy provides 1.3 billion tons of raw material annually and is a production potential of acid-hydrolyzed corn stover. common feedstock for fermentation systems used in The carbohydrate content of acid-hydrolyzed corn stover biofuel production.2 can be very high, and for some carbohydrates can even Corn stover is acid-hydrolyzed to release a water-soluble approach their saturation concentration in an aqueous mixture of carbohydrates, typically consisting of arabi- solution. When used for saccharide determinations, PAD nose, glucose, galactose, mannose, xylose, fructose, and with a gold working electrode is a sensitive detection cellobiose among other noncarbohydrate substances in method, but like other detection techniques it does not 0.5 to 1.5% (w/w) sulfuric acid.3,4 The concentration of have an unlimited linear range.
    [Show full text]
  • Lecture 2 Assistant Lecture Tafaoul Jaber
    Lecture 2 Assistant Lecture Tafaoul Jaber Effect of alkali on carbohydrates Benidict , Fehling , Barfoed tests . These tests are based on the most important chemical property of sugar, the reducing property. Benidict and fehling tests are used to determine presence of reducing sugar while Barfoed test is used more specifically to distinguish monosaccharides and disaccharides. Reducing and Non- reducing sugars Sugars exist in solution as an equilibrium mixture of open- chain and closed-ring (or cyclic) structures. Sugars that can be oxidized by mild oxidizing agents are called reducing sugars because the oxidizing agent is reduced in the reaction. A non-reducing sugar is not oxidized by mild oxidizing agents. All common monosaccharides are reducing sugars. The disaccharides maltose and lactose are reducing sugars. The disaccharide sucrose is a non-reducing sugar. Common oxidizing agents used to test for the presence of a reducing sugar are: Benedict's solution, Fehling's solution. Benedict's Test Benedict's test determines whether a monosaccharide or disaccharide is a reducing sugar. To give a positive test, the carbohydrate must contain a hemiacetal which will hydrolyse in aqueous solution to the aldehyde form. Benedict's reagent is an alkaline solution containing cupric ions, which oxidize the aldehyde to a carboxylic acid. In turn, the cupric ions are reduced to cuprous oxide, which forms a red precipitate. This solution has been used in clinical laboratories for testing urine. RCHO + 2Cu2+ + 4OH- ----- > RCOOH + Cu2O + 2H2O Hemiacetal & hemiketal formation Procedure Place 1 ml of carbohydrates solutions in test tube. To each tube, add 1 ml of Benedict's reagent.
    [Show full text]
  • MINIMIZATION of SUCROSE LOSSES in SUGAR INDUSTRY by Ph and TEMPERATURE OPTIMIZATION
    The Malaysian Journal of Analytical Sciences, Vol 12, No 3 (2008): 513 - 519 MINIMIZATION OF SUCROSE LOSSES IN SUGAR INDUSTRY BY pH AND TEMPERATURE OPTIMIZATION Kornvalai Panpae 1*, Wasna Jaturonrusmee 1, Withawat Mingvanish 1 , Chantana Nuntiwattanawong 2, Surapon Chunwiset 2 , Kittisak Santudrob 1 and Siriphan Triphanpitak 1 1Department of Chemistry , Faculty of Science , King’s Mongkut’s University of Technology Thonburi, Bangkok 10140, Thailand 2Chaimongkol Refined Sugar Company, Limited.( U-Thong Factory ), Supanburi Province 72160, Thailand * Corresponding author: [email protected] Abstract Invert sugar has several disadvantage properties that play an important role in many food applications. It has a high affinity for water and is the cause of making products retain moisture.Invert sugar also affects the caramelization process , producing a browning effect. In this study, the possibility of minimization of sucrose inversion during the industrial production of sugar cane was investigated by the variation of the important parameters, i.e. temperature and pH of sugar cane juice for each of samples. The amounts of sucrose and reducing sugar alerting during the sucrose inversion process were determined by the values of % Pol and % reducing sugar (% RS), respectively. Starting with the study of temperature and pH effects of the sucrose solution with the concentration of 16 Brix, used as a sample model, it was found that no change in amounts of reducing sugar and sucrose was observed at room temperature (34 oC) in the pH range of 5-11. At pH 3, the amounts of reducing sugar increased and the amount of sucrose decreased as the time increased.
    [Show full text]
  • Converting Galactose Into the Rare Sugar Talose with Cellobiose 2-Epimerase As Biocatalyst
    molecules Article Converting Galactose into the Rare Sugar Talose with Cellobiose 2-Epimerase as Biocatalyst Stevie Van Overtveldt, Ophelia Gevaert, Martijn Cherlet, Koen Beerens and Tom Desmet * Centre for Synthetic Biology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Gent, Belgium; [email protected] (S.V.O.); [email protected] (O.G.); [email protected] (M.C.); [email protected] (K.B.) * Correspondence: [email protected]; Tel.: +32-9264-9920 Academic Editors: Giorgia Oliviero and Nicola Borbone Received: 17 September 2018; Accepted: 29 September 2018; Published: 1 October 2018 Abstract: Cellobiose 2-epimerase from Rhodothermus marinus (RmCE) reversibly converts a glucose residue to a mannose residue at the reducing end of β-1,4-linked oligosaccharides. In this study, the monosaccharide specificity of RmCE has been mapped and the synthesis of D-talose from D-galactose was discovered, a reaction not yet known to occur in nature. Moreover, the conversion is industrially relevant, as talose and its derivatives have been reported to possess important antimicrobial and anti-inflammatory properties. As the enzyme also catalyzes the keto-aldo isomerization of galactose to tagatose as a minor side reaction, the purity of talose was found to decrease over time. After process optimization, 23 g/L of talose could be obtained with a product purity of 86% and a yield of 8.5% (starting from 4 g (24 mmol) of galactose). However, higher purities and concentrations can be reached by decreasing and increasing the reaction time, respectively. In addition, two engineering attempts have also been performed.
    [Show full text]
  • Analysis Fo Sugars in Maple Syrup
    APPLICATION NOTE Liquid Chromatography Author: Jamie Foss PerkinElmer, Inc. Shelton, CT Analysis of Sugars in Maple Syrup by Hydrophilic Interaction Introduction Maple syrup is a popular natural Chromatography (HILIC) sweetener that the U.S. Food and Drug Administration defines as the with Refractive Index Detection liquid food derived by concentrating and heat-treating sap from the maple tree.1 Sucrose is the primary sugar found in maple syrup, along with lesser amounts of glucose, fructose and complex carbohydrates.2 Often, the total sugar content of maple syrup is based solely on the amount of sucrose, and does not consider the other sugar sources.2 Maple syrup also contains various other components including minerals, vitamins, amino acids, organic acids, and phytohormones.3 The sugar composition of maple syrup differs from honey, which is dominated by both glucose and fructose, and can contain other sugars such as sucrose and maltose, in much smaller concentrations.3 The analysis of simple sugars is commonly performed using high performance liquid chromatography (HPLC). Often, hydrophilic interaction chromatography (HILIC) is used with refractive index (RI) detection owing to the polarity of the sugars, and the lack of a suitable chromophore for UV detection. Therefore, this work describes a simple HILIC-RI method for the analysis of four common sugars found in maple syrup. The structures of these four sugars are shown in Figure 1. Fructose Glucose Sucrose Maltose Figure 1. Chemical structures of the four sugars analyzed in this study. Experimental Table 1. LC Parameters. PerkinElmer Brownlee Analytical Amino, 3 µm, Hardware and Software Column 150 x 4.6 mm (Part# N9303501) Chromatographic separation was achieved using a PerkinElmer LC 300 HPLC system, consisting of an LC 300 10K psi pump and an Solvent A: 75:25 Acetonitrile:Water Solvent Program: Isocratic LC 300 autosampler equipped with an integrated column oven.
    [Show full text]
  • Mechanism and Kinetics of Cellobiose Decomposition in Sub- and Supercritical Water
    Ind. Eng. Chem. Res. 1998, 37, 357-361 357 Mechanism and Kinetics of Cellobiose Decomposition in Sub- and Supercritical Water B. M. Kabyemela, M. Takigawa, T. Adschiri, R. M. Malaluan, and K. Arai* Department of Chemical Engineering, Tohoku University, Aza, Aoba, Aramaki, Aoba-ku, Sendai 980-77, Japan Cellobiose decomposition kinetics and products in sub- and supercritical water were studied with a flow apparatus at temperatures from 300 to 400 °C at pressures from 25 to 40 MPa, and at short residence times (0.04-2 s). Cellobiose was found to decompose via hydrolysis of the glycosidic bond and via pyrolysis of the reducing end. Pyrolysis products were glycosylerythrose (GE) and glycosylglycolaldehyde (GG) which were confirmed by FAB-MS. Hydrolysis products were glucose, erythrose, and glycolaldehyde from cellobiose, GE, and GG, respectively, as well as glucose decomposition products. The kinetics from glucose decomposition were used to fit the experimental results and evaluate rate constants of hydrolysis (kH) and pyrolysis rate constants (k1 and k2). The activation energy for the hydrolysis of cellobiose and pyrolysis products GG and GE was found to be 108.6, 110.5, and 106.1 kJ/mol, respectively. In the supercritical region, there was a decrease in the pyrolysis rates k1 and k2 and a corresponding increase in hydrolysis selectivity from 85% to 95% as the pressure increased from 30 to 40 MPa. Introduction Reaction times were in the order of 1-14 min, and the product analysis was able to account for 60% of the Cellulose hydrolysis products have the potential to cellobiose decomposition products.
    [Show full text]
  • Fructose, Glucose, and Sucrose in Nature
    3/13/2017 Fructose, Glucose, and Sucrose In Nature Fructose, Glucose, and Sucrose In Nature By Rex Mahnensmith | Submitted On July 04, 2016 Fructose, glucose and sucrose are often referred to as fruit sugars, and indeed they are. These sugars exist in virtually all tree fruits, in virtually all vine fruits, and in virtually all berries. Fructose, glucose, and sucrose exist in most root vegetables, as well. Fructose and glucose are circular molecules, very similar to each other. Each has 6 carbon atoms, 6 oxygen atoms, and 12 hydrogen atoms. However, the compounds differ slightly in the arrangements of these atoms. Both exist as straight chain molecules and as circular molecules. Both are highly reactive and will react with each other easily, forming sucrose. Glucose and fructose are two products of photosynthesis, whereby plants inspire carbon dioxide from the atmosphere and react this carbon dioxide molecule with water, forming simple single sugars or "monosaccharides." The photosynthetic steps are complex yet precise, yielding glucose principally, then fructose, and ultimately sucrose, which is the result of fructose combining with glucose to form a double sugar or "disaccharide." In the experimental setting, under direct observation, glucose, fructose, and sucrose appear almost simultaneously through the photosynthetic process. The sugar compositions of glucose, fructose, and sucrose differ from plant to plant. http://ezinearticles.com/?Fructose,­Glucose,­and­Sucrose­In­Nature&id=9460795 1/3 3/13/2017 Fructose, Glucose, and Sucrose In Nature For example, apples, figs, bananas, grapes, and pears are relatively rich with free fructose sugars when fructose­to­glucose ratios within these fruits are analyzed.
    [Show full text]