SD0100030
PHYSICO-CHEMICAL SfUDY ON GUAR GUM
A thesis submitted for the M. Sc. Degree in Chemist>trrv
NAHLA MUBARAK MAHMOUD
Department of Chemistry Faculty of Science University of Khartoum
May 2000'
32/ 37 CONTENTS Dedication ' :. , ,..'...... I Acknowledgement ..; II English Abstract '.'. „,..,...... lit Arabic Abstract V List of Tables VII List of Figures , ; VIII
CHAPTER ONE INTRODUCTION 1.1.0 Gums ; 1.1.1. Definition ...... ; 1.1.2. Seed Gums '; i 1.1.3. Exudate Gums '. ; L 1.1.4. Preparative Fractionation -> 1.2.0. Guar Gum ; n 1.2.1. Historical Background : --> 1.2.2. Guar Plant... 3 1.2.2.1. Description ^ 1.2.2.2. Classification of Cyamopsis tetragonoloba(L) Taubert , 3 1.2.2.3. Guar Seed j. 1.2.3. Extraction and Purification of Guar Gum 4 1.2.4. Structure , 7 2 5. Physico-chemical Properties of Guar Gum g ' 1.2.5.1 Viscosity . g 1.2.5.2. Viscosity-Molecular weight Relationship JJ .1.2.5.3. Specific Rotaion p 1.2.5.4 Trace Elements...; p .2.6. Molecular Weight 13 .2.7. Applications of guar gum p 1.2.7.1. Food Industry 14 1.2.7.1.1. Dressings and sauces ; , ] ^ 1.2.7.1.2 Beverages 15 1.2.7.1.3. Processed Cheese Products p 1.2.7.1.4. Baked Goods ,5 1.2.7.1.5. Pastry Icings • 1.2.7.1.6. Meat Binder 1.2.7.1.7. Canned Meat Products and Pet Foods 1.2.7. 2. Non-food Industry .....; ...... 17 1.2.7.2.1. Paper Industry 17 1.2.7.2.2. Mining Industry 17 1.2.7.2.3. Oil-Well Drilling 18 1.2.7.2.4. Explosives 18 1.2.7.2.5. Tobacco 18 1.2.7.2.6. Cosmetics and Pharmaceuticals 18 1.2.7.2.7. Ceramics, Asphalt and Coal 18 1.2.7.3. Applications of Guar Gum Derivatives 19
TWO EXPERIMENTAL 2.1.0. Source oF Materials 1(, 2.1".lv. Guar Gum Fractionation ^Q 2.2.0. Physico-chemical Properties of Guar Gum ....:... ^, 2.2.1. Infra-red Spectra ; Z^ 2.2.2. Moisture Content Z\; 2.2.3. Ash Content ^ 2.2.4. Nitrogen (Protein) Content ^ 2.2.5. Determination of pH ., 2.2..6. Determination of Viscosity ' ' ~ 2.2.7. Determination of Specific Rotation 23 2.2.8. Determination of Elements in Guar Gum
CHAPTER THREE RESULTS AND DISCUSSION 3.1.0. Fractionation of guar gum 25 3.2.0. Physico-chemical Properties of guar gum .....' 3.2.!. Infra - red Spectra •., ^ 3.2.2. Moisture content Z,n 3.2..3. Ash Content ~^' 3.2.4. Nitrogen ( Pi\-iein) Content ^~ 3.2.5. Del erm niation of pH -,o
3.2.o. Intrinsic A i-scosiiy on
3.2.7-. Molecular Weight Zo 3.2 ;S. Specific Hotation ; -,q v2N. Metal C>-:.ieiu ~
47 Dedication
To- my Acknowledgement
I would like to express my deep sense of gratitude and sincere ippreciation to my supervisor Professor Ali Mohamed KJieir for his :ontinuous encouragement, guidance and help throughout this work. I also wish to express my gratitude to all-members of the Chemistry Department, Faculty of Science, University of Khartoum,,for allowing me to ise their facilities and for their moral support. Special gratitude is extended to the staff of the Botany Department, •"acuity of Science, U. of K., for allowing me to use their laboratories and lbrary. ; Best regards are due to the Food Analysis Department,Research and ndustrial Consultancy Centre, for providing laboratory facilities. M>\ deepest thanks are offered to my family members for their n\ aluable assistance, endless support and encouragement. Thanks are extended to my friends and colleagues for their moral
uppori. . , • ' , I am also very grateful to Miss Hameida Elameen and Abd Elhadi Uxlalla for computer facilities. All praise is due to ALLAH who helped me and gave me health and
>atience to complete this revsearch. DISCLAIMER
Portions of this document may be illegible in electronic image products. Images are produced from the best available original document Abstract
Giiar plant is an annual summer plant and it can resists diseases, pests and drought. Guar gum is used in a lot of industries. The present study deals with some physical properties of two commercial grade samples of guar gum Cyamopsis tetraaonoloba which were produced in 1996 and 1997 seasons (Sjand Svrespectively). Our analytical data are compared with those of previous :workers in this area and international quality. Nitrogen content determination,showed that the gum samples had a value of 0.678% and 0.732% and water-insoluble fraction had a value of 0.118%. The values decreased in the water-soluble fractions giving 0.049%, 0.053% and 0.056%. Water-soluble component and its fractions record the following results: pH measurements showed that the water-soluble component had pH 6.70 and 6.84 while its fractions had pH 5.90 and 7.00 Viscosity measurements showed that water-soluble fractions had intrinsic viscosity of 6.4 and 6:8 dL. g' . The fractions derived from water- soluble fraction had intrinsic viscosity of 6.6, 7and 7.5 dL.g"1. Using Mark-Howink equation, the calculated average molecular weights for the water-soluble components were 7.01 x lO3 and 7.62xlO5 g mol"1 andifor its fractions were 7.31 x 105. .. 7.93 x 105 and 8.73xlO5 g mo!"1. The specific rotation for the whole water-soluble component was •i-58G and +59°, while that for the fraction samples increased and gave the values of+64°,+66° and+65°. X-ray fluorescence (XRF) method indicated that the gum samples and fractions contained traces of following elements: K, Ca, Mn. Fe, Cr, Zn, Pb. Cu, As, Ni, Se, Rb, Sr. Zr. Y, Nb.
iv LIST OF TABLES
1. Composition of the components of guar seed 9 2. Some physical data for samples of guar gum and its fractions- 32 3. Nitrogen and protein contents in samples of guar gum and its fractions 33 4. pH for samples of guar gum and its fractions 33
5. The flow time, ts. for water-soluble fractions of guar gum and its tractions at 25°C ., •'. ". ' 34
6. The reduced viscosity, (r]sp/ C%), for Fsi, Fsv Fi, F2 and F3 fractions of giiar gum at 25°C , 35 7. Intrinsic viscosity and molecular weight for fractions of guar giim
35 8. The optical rotation, a°. for water-soluble fractions of guar gum
and its fractions F!;F; and F3 at 25°C . 35 9. Comparison of specific Rotations, [a]^, of water-soluble
fractions FSJ and Fs^ of guar gum and its fractions at 25°C 36 '10 Dejennination of elements contained in samples and fractions of guar gum in % and ppm 37
(vu) LIST OF FIGURES
1. Guar plant before pods formation 5 .:. Mature guar plant 5
3. Guar pods and -seeds 6 -1. Transverse section (brought guar seed. 6 ;:>. Proposed structure' for guar gum 9 o. The infra-red spectrum of guar gum sample (S> ) 38
'.'. 1 lie infra-red spectrum of water- insoluble fraction (I) of
•guar gum -. .' 39
•A. 'ihe infra-red spectrum of fraction one (F| )of guar gum 40 l >. 1 he infra-red spectrum of fraction two (F2 )of guar gum 4 i
io. 1 he infra-red spectrum of fraction three (F3 )of guar gum. 42 I 1. Reduced viscosity . (]] / 0%) , versus concentration (C%)
j"or water- soluble fractions FSi and Fo of guar gum at 25°C. 43 1 ..:. Reduced visco-m;- . t \\^J i'%) , versusconeentration (C%)
tor 1- ;.Fj and F; fractions of guar gum a!;25°C. 44 i 1 Optical rotation u , \ ersus concentration (C°"o) for vvater-
M)luble iVaciioii-, oiOuar gtim FS! and' Fs: at 25°C -^ i-1. Optical rotatio!!-'.
'*-••
i ••. in ) CHAPTER ONE INTRODUCTION . INTRODUCTION
1.1.0. Gums: 1.1. 1. Definition: Water-soluble, gums are polysaccharidic materials which are more or less soluble in water to form a viscous solution, a gelatinous paste, or a jelly (depending on the concentration employed) and which are insoluble in most organic solvents. Using of 'water-soluble'gums, may be distinguished-from, similar-appearing tree exudates, the resins, which are insoluble in water but soluble in organic solvents .
1.1.2. Seed Gums: • (4) Seeds were also an ancient source of gums. It is generally accepted that the galactomannan (polysaccharide gum), is a reserve polysaccharide. which is utilized in germination. The vast majority of galactomannan polysaccharides extracted from higher plants have originated in the Leguminoseae family. The galactomannans from the seeds ofguarand carob (locust bean) have found widespread use , as industrial (5) ,••'... < hydrocolloids.
1.1.3. Exudate Gums: Plants that produce commercial gums are usuallly shrubs or low growing trees from which the gums exude as vermiform or tear shapes. Among exudate gums.'true gum arabic is a dried gummy exudation obtained from trees belonging to various species of the genus Acacia.
(1) : . ;L JL-4- Preparative Fractoir^tipn: ; The techniques for fractionating the polydisperse polymer are^divided into preparative and analytical methods/'* Preparative method ."is based on the fact that the solubility of macromolecules is a function of molecular weight. The partial precipitation is a result of the decrease in solvent power as controlled by temperature or by varying the ratio of solvent to non-
; solvent in a binary mixture. Precipitation is carried out by addition of ethanol or acetone to an aqueous solution of the polysaccharide. Differential solubility by , collecting. the different fractions of gum according to their solubility in distilled water (fraction A), salt (fraction B)' and the residual insoluble gel (fraction C).(8) Fractionation is, perhaps, more successful if derivatives are used. (9) Guar gum was acetylated. Then guaran triacetate was fractionated. (10) Gums can also be fractionated by careful precipitation with neSr saturated sodium sulphate solutions }]^ Polysaccharides in general can also be fractionated by precipitation with a specific complexihg agent.(9) Addition of small amounts of Fehling solution to aqueous solutions of guar gum causes the precipitation of a polysaccharide-copper complex.(12)
1.2.0. Guar Gum: Guar flour is the ground endosperm of guar seeds. Its industrial value rests upon the gum (78-82% of the endosperm) which is a natural, water dispersable, hydrocolloid. The hydrocolloid commercially known as guar gum is chemically a galactomannan - and designated guaran. 1.2.1. Historical Background: The early history of old-world legume guar is unknown. However, established records and circumstantial evidence indicate man cultivated guar In Indo-Pakistan subcontinent for numerous generations, until recently guar lias remained as a milfer crop. Guar plant (leaves,; Pods, and seeds) is; used for cattle feed saiid; human eorisumption. It is also used in medicinal purpose.(13) In the United States, guar, was first investigated as a source of gum in
, 1945. The consumption of guar gum has grown rapidly; since its commercial introduction in 1953.(14) Recently, Sudan has introduced guar as a cash crop to supply the only guaran producing company which is established in Singa town in 1996. However, guar plant is found as a local crop in the areas, of Red1 Sea mountains and Arashekol mountains at White Nile State/15)
1.2.2.Guar Plant: Guar plant is a drought-tolerent summer legume.
1.2.2.1. Description : Guar is an annual bushy branching plant. The length ofguar plant can reach 3m. Plants vaiy from 1-leader branch type to heavily branched one (Fig. 1). It has small pink ,to white flowers and alternated trifoliolate leaves (Fig.2)., It has well -developed lateral root system, with large light colored nodules. Pod length is 12 cm and carries 5-12 seeds (Fig.3). Pods emerge from just above the ground to the top of the plant in dense clusters. Plant maturity occurs in 125-135 days to 160-175 days.(16)
1.2.2.2. Classification of Cvamopsis tetragonoloba (L)Taubert Wtf.wo). Common Names . : Guar .Cluster bean, Siambean, Calcutta lucerne Synonym : Cvamopsis psoralioides DC.
13) 'Kinsdom = • • :. Plantae Phylum " Angiq spermae Sub Phylum : 'Diodtyledones Division " Lignosae Group Rosaceae , (Rosales), (Rutales) Grade Dialypetalae Order Leguminales Family Leguminosae Sub Family : Papilionoideae Genus •; ' -.: • ? Cyamopsis 1.2.2.3. Guar Seed: The guar seed is dicotyledonous, having a diameter of approximately 1/8 in ( 8mm) (Fig.3:).(14) ' In his pioneering work Anderson screened seeds of 163 species of legumes for sources of endosperm gums. He reported that guar seed contains about 50% endosperm and yielded approximately 42% gum. (lj) According to A. M. Goldstein, E. N. Alter and J. K. Seaman(l4) (Table 1) the major components of guar seed are the seed coat (14-17%), endosperm (35-42%), and germ (43-4.7%) (Fig.4). The germ contains most of the protein in the seed while the endosperm contains the galactomanhan gum. Menon et.al. found that gum content of a whole seed, endosperm content, and percentage of gum in endosperm varied between 1.9.1 - 34.1%, 38.0- 49.9% and 47-68%, respectively, in 86 guar seleenons grown in India in 1968.(b) 1.2.3. Extraction and Purification of Guar Gum :
The extraction on a commercial scale of galactomannan gum from guar seed usually invoh'es a preliminary removal of the tough seed - coat Ui
>5 ?^^&'b?f-j&^&j'*7i.±£m
Fig. 1 : Gnar FJant before pods formation Fig.2 Mature Guar plant Fig. 3 : Guar pods (A) and seeds (B)
Fig. 4 : Transverse section through guar seed
(6) by some form of milling on; grinding^ The digferehee in hardness of the various seed components is utilized, anS a
(7) 1.2,5, Physido-chemihal Propgifles^of
Guar gum is a non ionic neutral polysaccharide galactomannan. There are no standards for grade identification of guar gum. However, the available grades can be differentiated on the basis of purity and viscosity. Food-grade guar gum is stiDStantialy pure endosperm. It usually has a small residue'of hull and germ owing to imperfect purification. A typical analysis of the impurities in food-grade guar gum gives crude fiber 2.5 %; moisture, 10 -15%; protein , 5-6% ; ash, 0.5- 0.8% .A comparison of this analysis; with that of pure endosperm components (Table 1) shows the effectiveness of the separation as done by the usual commercial processing techniques. Technical - grade guar gum is usually a less purified gum. Most guar gums marketed to the food industry produce viscosities of 3000-5000: cps in a 1% solution . Viscosity is not only influenced by purity but also by processing techniques.
1.2;5.1. Viscosity: Guar gum forms viscous, colloidal dispersions (solutions) when hydrated in cold water/14 ' . Temperature influences the rate of hydration and development of maximum viscosity. Guar solutions prepared at higher temperatures reach maximum viscosity much faster than those at lower temperatures. However, the advantage of using heat to achieve faster hydration ,of the gum'is partly offset by the possible degradative effect of prolonged heat in certain processing conditions . The maximum viscosities of guar gum dispersions are achieved at temperatures of about 25-40 C.(lj) In dilute'solutions, the viscosity of guar gum increases linearly with concentration up to about 0.5%. Thereafter, guar gum solutions behave as
(8) Fig. 5 : Structure proposed for guar gym
rr
Table 1: Composition of the Components of Guar Seed
•••' ' Seed part K1 Protein Ether > Ash Moisture, Grude Type of , (N X 6.25) % Extract, % % % Fiber, % Carbohydrate Hull (14-17%) 5 0.3 4 10 36.0 D-Glucose Endospem 5 0.6 0,6 10 1,5 Galactomanan (35-42%) 55.3 5.2 4.6 10 18.0 D-Glucose Genn(43-47%)
(9) non -'Newtonian solutions-mainly as a result of#he complex surface attraction•'*•••••s at highe• ' r concentration;•'•-." i : '<**' * Guar gum is stable over a wide pH range. The nonionic nature>:of the molecule is responsible for the almost constant viscosity of solutions in the pH range 1-10.5 .# However, previously hydrated guar gum is compatible with high alkalinity; and modified guar gums that develop high viscosity in concentrated, caustic solutions have recently become available. The optimum rate of hydration for guar gum occurs between pH 7.5 and 9. Despite the rate differences, maximum viscosities are the same in both (14) acidic and alkaline media. Guar gum is nonionic. Therefore compatibility with salts is exhibited over a wide range of electrolyte concentration. High concentrations cf multivalent salts affect hydration and produce gels. Guar gum is compatible with many materials, including pearl starches and with most other gums such as gum arabic . It acts synergistically to increase viscosity when, combined with.some other gums or with starches. In the presence of sugar, guaran competes with the sugar for the available water, and high percentages of sugar have a marked delaying action on the hydration of the gum . In addition, the viscosity of guaran-sugar solutions decreases gradually in direct proportion to the sugar concentration . Sugar is effective in protecting guaran solutions against hydrolysis and loss of viscoity when solutions are heated or autoclaved. The presence of 5-10° b (13.25.26) sugar in the liquid gives improved viscosity. Guar gum solutions require a hydration time of about 2 hrs to reach maximum viscosity. The gradual decrease in viscosity which occurs after 24 hrs is usually accompanied by a drop in pH. Two factors responsible for this viscosity decrease are fermentation -and enzymatic hydrolysis.
.0) However*, bacteriosfatic and bacteriocidal preservatives: in siffficient concentrations j5rovi Relative viscosity rjr = T]soi, / r)soiv. = tsoi./tsoiv. (1) Specific viscosity risp. = rj r - 1 (2) Reduced viscosity rjred. = r)sp/C (3); Inlierent viscosity rjinh. = (Ln r|r)/C (4) Intrinsic viscosity [r\]• = ( rjsp./C }c = o = [( Ln r|r) /C]c = o (5) The intrinsic viscosity [r\] is the quantity usually correlated with molecular weight: * a [r\] = K'Mv (6) Mark-Houwink equation. Mv is the viscosity - average molecular weight. The constants K' and a must be determinded for each experimental system by measuring the intrinsic viscosity of polymer samples whose molecular weight is known as the result of other measurements. Since Mv is not usually available, and because Mv is more nearly equal to ivlw than to other average molecular weights, it is common to use values of Mwto calibrate the viscosity method, and to rewrite equation (6): [il ] - K/' IVUa (7)(27) (11) Molecular theories of the' viscosity of dilute and more concentrated solutions of random-coil .polymers have been applied to five molecular •weight fractions of giiar galactomannan. The staudinger constants k and a, were calculated. Values deduced were K - 3.8 x TO and a -0.723. l2M 1.2.5.3. Specific Rotation: i The .optical -activity of-organic molecules is related to their structure and is a characteristic property of the substance .(29j Although polarized light has many uses , to the physical chemist one of its principal functions .is in polarimetry, the measurement of the angle of rotation, that is, the angle through Which the plane of polarization of the light is rotated by passage of the beam through an optically active material •This rotation or change in the plane of vibration of the plane-polarized light depends upon the wave length of the light, the-nature of the material, its density or concentration, and the length of the light path.{M)} Vibrational Raman optical activity spectra of carbohydrates in aqueous solution associated with the glycosidic linkage in the saccharides were measured between 700-1500 cm.(il) Guar gum gives 'dextrorotatory optical rotations in solution. It has a specific optical rotation of ~53'21'and+54.5(21"-2' in I N sodium hydroxide solution. • 1.2.5.4. Trace Elements: The basis of quantitative X-ray fluorescence spectrometry(XRF) is: to follow the identification of a certain element (the matrix) • with a measurement of the intensity qf one of its characteristic lines, then to use this intensitv to estimate the concentration.of that element.(j3) (12) I.2.6.- Molecular Weight: Galactomannans,' like many other natural polysaccharides, tend to be polydisperse and,- consequently, can not be accurately described by a single molecular weight. Instead, average molecular weights are obtained, the values of which are dependent on the techniques used. Anumber of problems arise in connection with the measurement of molecular weights of galactomannans. Firstly, it is very difficult to obtain true solutions of many of the gums, especially of locust-bean gum and guar gum. Consequently , the solutions must be filtered or centrifiiged to remove undissolved or partially hydrated gum. This immediately raises the problem of fractionation of the sample, as the result may not mean very much if a large portion of the sample is removed before analysis. Secondly, the values depend upon the rigorous evaluation of the molecular shape. For example, Deb, And Mukheriee used a dissymmetry method and assumed for molecules of guar gum a spherical shape, which is highly unlikely; the molecular weight derived was 1, 720,000, a value that seems unreasonably large but may, however, be due to aggregation. A third problem, pertaining to chemical methods, arises because of the very high molecular weights of some galactomannans .Agum having a molecular weight of 250,000 has only one reducing end - group for every fifteen hundred or so sugar residues; thus, in methods involving end-group analysis, avery high level of accuracy is required; in addition, highly purified samples are essential. Periodate-oxidation methods can be complicated by over-oxidation. ^ By the application of membrane osmometry to a commercial sample of guar gum, a number-average molecular weight of Mn = 240,000 for both the gum and its peracetate was obtained. Light -scattering and viscosity measurements gave a weight-average molecular weight of M,v = 950.000. The large difference between Mn and Mw indicated the presence of species having a broad spectrum of molecular weight in p ommercial guar £um.(5) Using a modified version of the Launer and Tomimatsu assay Mn of guaran was found to be 250,000 while Mwis 1,900,000 determined with a Spinco ultracentrifuge.(34) 1.2.7.0. Applications of Guar Gum: 1.2.7.1. Food Industry: 1.2.7.1.1. Dressings and Sauces: Advantages of using of guar gum in salad dressings are: its cold - water dispersibility, its compatibility with highly acidic emulsions, and its , comparatively low cost on asviscosity basis. It functions as an femulsion stabilizer by increasing the viscosity of the aqueous phase, thereby decreasing the separation rate of the water and oil phases. Guar is useful as a thickener in pickle and relish sauces when rapid cooling is used. It provides good body, a clean appearance, and it can be prepared in solution. The addition of guar gum to barbecue sauces and similar meat sauces is effective in stabilization. The gum reduces the tendeny of the .sauces to separate and improves the: shelf life of the final products. 1.2.7.1.2. Beverages: Guar is often used as a thickening or viscosity control agent in beverages. Sugarless dietetic beverages require incorporation of a gum to improve body and mouth feel. Guar gum is useful because of its resistance to breakdown under the low pH conditions. In addition, since guar is soluble in cold water, it is easy to use in most beverage processing plants.lt is economical to use and practical because of its high viscosity, fast hydralion rate, and extremely bland flavor. (14) ^•Bi|fi|| of 'guar gum and carrageenan* are used • in certain cocoa products as effective stabilizing and suspending agents. 1.2.7.1.3^ ^Processed Cheese Products: The use of guar gum in cold-pack cheese products eliminates syneresis or weeping and improves texure and flavor.In soft cheeses, the use of gifergum increases the yield of curd solids and produces curds,of a soft, compact, tender texture with a separated lipid whey. Guar gum also adds to pasteurized processed cheese as a stabilizer. Guar gum has a broad application in frozen foods because of the stability of its aqueous dispersions or solutions. This hydration ability and water-binding property also makes the gum useful as an ice cream stabilizer and especially useful in high-temperature, short-time processes. 1.2.7.1.4. Baked Goods: Stabilizers are often added to packaged cake mixes and guar gum offers several functional advantages in single-step mixing procedures: reduced batter mixing time, reduced crumbling in the finished cake, easier application of frostings and icings, and greater moisture retention during prolonged shelf life. Guar gum is also suitable for use in frozen cakes. The addition of guar, solutions to doughs while kneading give increased yields and produce a dough of greater resiliency and a drier, less flabby appearance. Baked products have a better, softer texture as well as a longer shelf life. In cake and biscuit doughs, the addition of guar gum yields softer and more moist products that are more readily removed from their pans and easily sliced without crumbling. When guar gum is added to batters of doughnuts, spoon bread, etc., it imparts desirable binding and film-forming properties that retard the penetration of fats and oils. (15) - Addition of guar gum to starch-gluten loaves of bread produced an i V', '. •'• • i ''."-'' ..' • '•,' ' \' ' ' • '' '•• • , .- I^.-'-.i \-.-j»..-ii itj •:••.** ••• ,'.,•'•;•';• : < effective" increase in baked loaf volume. In frozen pie-fillings, guaf gum- starch corhbiriatiohs are effective in preventing dehydration, shrinking, andi cracking of the filling. ; 1.2.7.1.5. P^itry Icings: Acomrhon ^problem in packaged iced bakery goods is the accumulation of moisture within the transparent wrapping. The moisture causes !the icing to adhere to the wrapping and results in an unpleasant appearance. Addition of guar gum to icings eliminates this problem by absorbing the free water. 1.2.7.1.6. Meat Binder: The strong water-holding properties of guar gum in both hot and cold water make it effective as a binder and lubricant in the manufacture of sausage products and related stuffed meat products. 1.2.7.1.7. Canned Meat Products and Pet foods: In the processing of canned meat products, the addition of guar gum offers reduction of the bumping tendency during the cooking of the meat products; increase in the ease of pumping of the cooked product; reduction of splashing and spilling of contents while filling cans, thus making control of fill weights easier and keeping the cans cleaner for labeling; viscosity control of the liquid phase during processing and cooling; and greater resistance to sterilization temperatures. Advantages in the finished product include prevention of fat migration during storage, control of free water separation in the can during storage and reduction of the tendency for void development in the can.(lj) (16) 1.2.7.2. Nori- Food Industry: r.2.7.2.1. Paper Industry: , Guar gum is used as a size for paper and textiles.f3:>) The major use of galaqtomannan in paper making is in the wet end of the process. The gum is addecl to the pulp suspension just before the sheet is formed. Galactomannans replace or supplement the natural hemicelluloses in paper bonding. Advantages gained by addition of galactomannans to pulp include improved sheet formation with a more regular distribution of pulp fibers (less Fiber bundles); increased mullen bursting strength; increased fold strength ; increased tensile strength; increased pick; easier pulp hydration; improved finish; decreased porosity; increased flat crush of corrugating medium; increased machine speed with maintenance of test results; increased retention of fines.(b) l.2.7;2.2i Mining Industry: Guar gum is used in froth flotation of potash as an auxiliary reagent, depressing the gangue minerals, which might be clay, talc or shale. Guar gum is also used as a floceulant or settling agent to concentrate ores or tailings in the mining industry. Guar gum is approved by the U.S. Public Health Service for use in potable water treatment as a coagulant aid in conjunction with such coagulants as alum (potassium aluminum sulfate), iron (III) sulfate, and lime (calcium oxide). In industrial waters, guar gum flocculates clays, carbonates, hydroxides and silica when used alone or in conjunction with inorganic coagulants. 1,2.7.2.3. Oil - Well Drilling: Water -Soluble polymers Have found a broad range of application in the production of petroleum. They serve one or more functions, such .as (17) water-loss control, viscosity control, flpcculation, suspension, turbulent friction reduction or mobility control.(13) 1.2.7.2.4. Explosives: In the production of water-resistant ammonium nitrate stick explosive, guar gum is used as a binding agent.(36) It is also used as a thickner and gelling agent for slurry explosives.(14) 1.2.7.2.5. Tobacco: Guar gum is used as a binder in making reconstituted tobaccco.(j/) 1.2.7.2 .6. Cosmetics and Pharmaceuticals Guar gum is used to thicken various cosmetics and pharmaeeutieals.(38) It is also used as a binder and disintegrator for compressed tablets.(39) Coarse granulations 6f guar gum are ordinarily used for this purpose. Guar gum in larger doses is being investigated as a bulk laxative.(14) 1.2.7.2 .7. Ceramics, Asphalt and Coal: Guar gum is used as a thickening agent in asphalt emulsions and ceramics.(40) It is also used as dispersant to stabilize aqueous powder of coal slurries. 1.2.7.3. Applications of Guar Gum Derivatives: There are some of the more important, industrial derivatives thereof include the carboxymethyl'ether, oxidized guar gum, andhydroxyalkyl ethers. (18) Regular guar, for 'example, is rapidly adsorbed onto hydrated mineral surfaces by hydrogen bonding to cause- flocculation. E5y the introduction of hydroxyalkyl side chains, adsorption rates are modified. In this way, a slightly reduced flocculation rafe to almost no flocculation can be achieved for a wide range of mining applications. Similarly, guar interacts with hydrated cellulosic surfaces to affect the formation and strength of a sheet ^during paper production. By hydroxyalkylation of guar, adsorption rates onto hydrated cellulose surfaces are altered for certain useful paper making applications. One of the novel improvements attainable through hydroxyalkylation of guar is solubility in water- miscible solvents such as glycols and alcohol. Solvent miscibility enables hydroxyalkyl guar derivatives to be used as thickeners for certain slurry explosives . Hydroxyalkyl-guar is . suited to textile thickening and; sizing (141 operations. ' • Carboxymethylated guar gum is used in food industry. It was evaluated as a thikener in printing of cotton textiles with reactive dyes.(4j 5 (19) CHAPTERTWO EXPERIMENTAL 2. EXPERIMENTAL > 2.1.0. Source of Materials: Guar gum ;'is milled endosperm from the1 seed of Cyamopsis tetragonoloba plant. Production of 1996 and 1997 were kindly supplied by Sudanese Guar Company Ltd. Singa. The two commercial samples were named'Si and ;S2 respectively .The water-soluble component of each commercial samples were extracted and named Fsi and Fs2 . The present study deals with structure, general composition and properties of guar gum , particularly water-soluble component. 2.1.1. Guar Gum Fractionation(44'21): One litre of 0.3% aqueous suspension of guar flour (S2) was prepared. Guar flour was readily separated into water - soluble and water - insoluble components. The water-insoluble component was separated from soluble component by centrifuge. It was washed repeatedly with fresh portions of acetone. After the final washing, the brownish white precipitate was dried over calcium chloride in a vacuum desiccator. It was then ground, stored in stoppered tube and named (I), The water- soluble component of guar gum (Fs2) was poured into a 3- necked 3 litres round-bottom flask connected with a mechanical stirrer and separator/ funnel. Acetone (95% w/v) was added drop by drop from a separator/ funnel to the stirred solution. When a suitable quantity of fine white filaments of gum was formed, the additon of acetone was stopped. This phase was obtained by adding 100ml acetone. The solution was allowed to stand overnight. Then the precipitate was separated by centrifuge, washed repreatedly with fresh portions of acetone and dried in a desiccator. It was then gound.and stored in stoppered. tube. This was considered as fraction one (F[). (20) This operation was repeated with fraction two (F2) and fraction three (F3) respectively by successive addition of 30 rfil acetone portions. 2.2.0 Physico - Chemical Properties of Guar Gum : 2.2.1 Infra - Red Spectra^ : Infra. - red spectra of S2 sample (1997 product), I (water - insoluble ! fraction) V\t F? and F3(water-soluble fractions) were recorded in the region 600 - 4000 cm"1 using Perkin - Elmer 1330 IR spectrophotometer. 2.2.2 Moisture Content*2!: l.Og Sample (Si,S2,1, Fi,F2 and F3) was heated in a porcelain crucible in an oven at 105°C for 6 hrs. It was then cooled in a desiccator and weighed, The procedure was repeated until a constant weight was obtained . The percentages of the moisture, contents were calculated as follows: Moisture %= (Wi-W2) x 100 Where: Wj = oiginal weight of t.he sample : W2 = : weight of the sample after drying 2.2.3. Ash Content(2): . l.Og of sample (S),S2, I jFj,F2 and F3) was weighed to the nearest 0.00lg in a dry porcelain crucible . The crucible was ignited in a muffle furnace at 550°C for 6 hrs, until free from carbon . It was then cooled in a desiccator and weighed The procedure was repeated to a constant weight of a carbon free ash. The percentages of the total ash of dry samples were obtained by the following equation: (21) Ash% . = • ' Weight of residue . x 100 Weight of sample. 2.2.4 Nitrogen (Protein) Content (45,46). Nitrogen content was determined by a semi-micro-Kjeldahl method. 0.2g of each sample (SI,S2>I,F1,F2 and F3) was digested in a small digestion flask using 0,8g: of catalyst mixture (96% anhydrous sodium sulphate, 4% cupric sulphate) .2ml of concentrated sulphuric acid were added to the flask and the contents were digested for 3 lirs till clear liquid was obtained. The digest was cooled, diluted and then transferred to the distillation unit using minimum volume of distilled water. It was then made alkaline with 20 ml of 40% aqueous sodium hydroxide solution. The ammonia was distilled into 1.0ml of 25 boric acid solution for half an hour. 3drops of bromocresol green- methyl red mixed indicator were added. The apparatus was steamed out for 5 minutes and then distillate was titrated with 0.0IN HC1. • The nitrogen and crude protein percentages were calculated according to the following equations: • •. Nitrogen % - V x NA x 0.014x100 • ).-.' W Where: '.';-:• ; V = the volume of titrant. NJV ,, T= normality of the acid. , W L- weight of the sample Protein % = Nitroeen % x 6.25 ' •(22) 2.2.5. Determination of pH: pH of the solutions of whole guar gums ;0.25%.to 0.05% were determined using Kent Eil 7020 pH meter at 35°C . pH of the solutions of fraction gums F], F2 and F3 were also determined by the same method. 2.2.6. Determination of Viscosity(47'48): 0.25% aqueous solution: was prepared from each water-soluble component (Fsj and Fs2) of guar, gum and eachfractions (Fl5F2 and F3). The rates of flow recorded for successive dilutions (0.25% to 0.05%) using the Ubbelohde viscometer in-a constant temperature water bath at 25°C . The viscosities of these solutions were determined . 2.2.7. Determination of Specific Rotation (49'50): •••"••• 'The specific rotations of, 0.25% to 0.05% for Fsi, Fs2 (whole water- soluble component) Fj, F2 and F3 (fractions), aqueous solutions were determined using Perkin -Elmer polarimeter. The polarimeter tube, 100mm in length, was filled with the solution. It was then placed in the- polarimeter and kept at 25°C in at use of water bath. The specific rotations were determined according to the following relation: ; [aft,= 100 a LC Where : •. \ [o.}'{) = specific rotation for a given wavelength (589nm) at a given temperature (25°C). a .= observed angle of rotation (23) L = length of light path in decimeters ; . C •=• • concentration of solute, g solute/lOOml solution.. 2.2.8. Determination of Elements in Guar Gum(51): In common with other methods of physico-chemical analysis, the analysis of low concentrations by X-ray fluorescencce spectrometry can be defined in terms of the ability to detect and measure a very weak response superimposed upon a back ground of almost equivalent strength .(JJ} In this study, X-ray fluorescencpe (XRF) was used to determine the contents of some of metals (atomic number > 18) present in guar gum. The XRF spectrophotometer used was Cd-109 XRF system : Cd - 109 annular X-ray excitation source, Pop Top Si (Li) detector Model SLP 06175-P, Canberra Bin Power Supply, High, Voltage Power Supply, Spectroscopy Amplifier, Series 35 Plus Multichannel Analyzer (MCA) . Before analysis, gum samples (Si and S2),water- insoluble component (I) and water- sojuble fraetions( Fi,F2 and F3 )were prepared in,pellet form, using a pressing machine. Each time a pellet was placed centrally on top of the Cd -109 source to be irradiated. The counting was started by processing and displaying, of amplified signal on MCA which is connected directly with a computer where the X-ray spectrum is analysed. . (24) CHAPTER THREE RESULTS AND DISCUSSION 3. RESULTS AND DISCUSSION Guar'igurn has^ emerged as a -new industrial crop. It can be.expected that the demand for guar gum will continue to increase. ! i Guar gum production in Sudan is a very recent development only started in 1996. Its application in non - food industries was unknown in the country.Though, it has been used' in food-industry recently. •Guar gum is, indeed , a versatile product. The physico - chemical properties of guar :gum are important in their industrial applications. ; ! • Marketed • ;guar gum : is the endosperm flour. It is separated and .ground by the usual mechanical processing technique that does not produce completely pure, endosperm. Therefore, the gum is not perfectly pure but contains small amounts of hull and germ. Contents such as protein,, ash. and moisture are considered as guar gum impurities. Since the whole seed is edible, this contamination dilutes slightly the amount of gum quality. 'but does not harm its suitability as a food additive. 3.1. Fractlonatoin of Guar Gum: E. Heyne and R.L. Whistljsr, separated water- soluble component of guar gum into 17 fractions. Analysis of the fractions indicated that tractions (3) to (12) were identical in composition (galactomannan polysacchande); they represent the main portion that precipitates in 2,5 - 40% ethanol. Fractionation of guaran acetate into 7 parts showed that they have identical optical rotation.(2l) P.'A. Hui and H. Neukom fractionated guar gum to (a) cold-uater soluble, (b) hot -water soluble and (c) hot-water insoluble fractions. They found a wide spread of sugar compositions and variation in molecular vveight of separated fractions.(:i2; (25) The present study,, fractionation by addition of acetone to water-soluble component- (at room temperature) of (commercial grade sample (S.,) of guar, gum has been carried out and some of physico-chetnical parameters have', been determined. Results are compared between whole and gum fractions and among gum fractions themselves. Table (2) shows some physical data for the two comrnercial products of guar gum (S S,). the water-insoluble fraction (at room temperature) and the three fractions that separated from water-soluble fraction. Table (2) also explains the, percentages of their yields. 3.2.0. Physico-chemical Properties of Guar Gum: Guar gum used was yellowish white flour. It was dissolved in water forming aqueous suspension. , Discarding of water-insoluble fraction resulted in clear water-soluble fraction. Guar gum solutions behave as non- Newtonian solution up to the concentration about 0.5% . 3.2.1. Infra-red Spectra: Figures (6) (7) (8) (9) (10) show the characteristic functional groups of a commercial .sample of giiar giim (S ),. water -insoluble fraction, (I) and f - . . • • •• ; - water - soluble fractions (F} ,F7 and F3). The frinctional groups of the five samples concide with the structure of galactomannan polysaccharide t--1--4-01 (1- 4-p-D-mannopyranosyl units,with a- D- gaiactopyranosyl units). Although water - insoluble fraction contains high percentages of fibre and protein, it contains also amount of galactomannan polysaccharide. (26) 3.2,2. Moisture Content: /• Table (2) shows that the moisture content p;.2, 7,8%) for the whole gum Sj and S2 respectively. They are in close agreement with the value reported by Thomas et al.(5%)(56) , but they are lower than the range of; moisture content reported,by Whistler ( 8-12%)(13\ ; The water-soluble fractions have moisture contents (5.2% ,5.3% ,7.5%) higher than that of water-insoluble fraction (4.7%) due to their higher content of gaiactomannan polysaccaride(gum).Among the fractions F3 has the highest content of moisture. 3.2.3.Ash Content: Table (2) shows the ash content for the two commercial samples SK and S2 (1.14, 0.81% respectively). The ash content of S2 is in the ranged reported by Whistler (l3) (0.5 -1.0% ) and Sj content is in close agreement with the range. : The values of ash content for the water-soluble fractions are (0.66%, 0.60%, 0.50%) lower than that of the whole samples . Water-insoluble fraction has ash value of 0.88% higher than values of water- soluble fractions. This may be due to the'presence of hull and germ constituents! that can mix during separation processing. 3.2,4. Nitrogen (Protein) Content: From Table (3) the values of protein content for the two commercial guar gum samples are 4.24% , 4.58% nearly somewhat in agreement with 5% ihe value which reported for pure endosperm in Table(l)°4). They are also within the range (4% -5%) reported by Stein, Mall and Co. (D7) for protein content in commercial guar gum. Water-soluble fractions contain only traces of protein (0.31% ,0.33% and 0.35%). F3 has the highest content of nitrogen. Water-insoluble (27) fraction contains slightly greater percent of protein ;(0.74%) than water- • ..;.{ • • •»•.-,;:• •• i * - " ; • " "• • • ; • } • " .-..'.•<•'• .'- ':- - '• ' ; soluble fractions because it was contaminated with hMl and germ. 3.2.5. Determination of pH : Guar gum is neutral'gum. It has no uronic acids.Neutral gums such as guar gum usually form solutions which are not dependent on pH . Table (4) shows that the pH values of whole gum (6.7, 6.84) and of fractions Fi,F2 and F3 7.0, 5.9, 5.9 respectively. 3.2.6. Initrinsic Viscosity : Viscosity is a commercial value of the gum. The higher the viscosity of the: gum, the higher its .commercial value. Gums are industrially demanded according to their viscosities. In our study , Table 7 shows that the intrinsic viscosities are 6.4, 6.8 dl.g"1 for the whole water - soluble fractions and 6.6, 7.0, 7.5 dl.g"1 for its fractions. F3 represents the highest value. In general there is little variation in the intrinsic viscosity values of the whole samples- (Fsj and FS2) and fractions (F| ,F2 and F3). Gums having a high content of D-galactose have viscosities higher than those of gums with lower D-galactose content/^ Therefore, the variation in the intrinsic viscosity values of the fractions ensures spread of sugar compositions in guar gum. 3.2.7. Molecular-Weight: The variation in the molecular weight values reported in literature for guar gum is due to the difference in sample preparation, purification of samples and the techniques used. (28) Table (7) shows that the molecular weights of the two water-soluble component of the commercial samples (7.01 x 103, 7.62 x 10 '"* g mol"'). The values are close to 9.5 x 105 which resulted by using light -scattering and viscosity measurements.(3) Although in the latter, the value of molecular weight was calculated from viscosity data by using constants derived by Koleske and Kurath differ from the ones we used. The values of average molecular weights in our study are lower than 2.2 x 106 (58 > and 1.9 x 106 (5} but they are within the range (500,000 - l,000,000)(59) reported in the literature. Again Table (7) shows that molecular weight of the three fractions 5 5 5 (F,;F2 and F3) are 7.31 x 10 , 7.93 xlO and 8.73x10 . F3 has the highest value of molecular weight. Although there is variation in molecular weights of samples and fractions , but it is not far. From results of Hui and Neukom(:i2): galactomannans which make up guar gum differed in the ratio of galactose to mannose, cold water-soluble fraction 1:1.3 while hot water - soluble fraction 1:1.7 water-insoluble ratio i:7 and original sample 1:2. That reflect a wide spread of sugar compositions in guar gum and ensures polydispersity in molecular weight observed in our results. 3.2.8. Specific Rotation : Table (9) gives the values of specific optical rotation for Fsi and Fs2 H-580.- 59°). It also shows the specific optical rotations of fractions (+64°, -66°, -r 65°). F2 represents the highest value and the values of the three fractions are higher than those of the whole sample. All of them are lower than, the value of +77° reported by P.A. Hui and H.Neukom.(:>2) (29) 3.2.9. Metal Content: The metals Ca, K, Na, Mg, Fe , Zn ,Cu and Mn play an important role in physiological effects and nutrition. The presence of metals in addition to carbohydrate and protein has made guar glim of high potential for the use in food industry and Pharmaceuticals. Table (10) shows the element content (atomic number >18) in percentages and ppm. Arsenic, lead, zinc and copper contents is very important in determining the level of toxicity. They must not exceed certain level. Minimum standards for good quality guar gum powder have been defined in the United States and by European Union Specification as follows: As: maximum 3ppm, Pb: max. lOppm, Zn and Cu: maximum 50ppm. In our study, commercial samples and fractions (Table 10) contain As, Pb, Zn and Cu within the standard limits. 3.3. Conclusion: Guar gum is a natural high molecular - weight hydrocolloidal polysaccharide. It is composed of galactan and man nan units combined through glycosidic linkages, which may be described chemically as galactomannan. Dissolved in cold or hot water, guar gum forms a slime of high viscosity. We have succeeded in obtaining optically different compounds of varying molecular masses by fractional precipitation of guar gum using acetone after separation of water-insoluble components by centrifugation. This fractionation of gum confirmed the polydispersity in molecular weight. The differences between water-insoluble fraction and water-soluble iVaciions in contents of metals, protein, moisture and ash .In addition to (30) above differences , the water-soluble fractions differ from each other in their molecular masses(viscosity) and specific rotations.. ; In comparison with other gums like locust bean >gum,(52) gum tragacanth(61) and gum arabic(62), giiar gum is amuch more homogeneous polysaccharide because of little variation in molecular weight values (viscosity) between water-soluble fractions in addition to a small amount of water-insoluble fraction in the whole sample. (31) Table 2: Some physical data for samples : ! ofzuargiim and its fractions Sample Fractionation Moisture % Ash % Yield % Si • • — 5.2 , 1.14 s2 ___ . 7.8 0.81 ' :*I ; / ; 24.0 , .; 4.7 i 0.88 F, 34.0 5.2 0.66 F2 18.2 5.3 0.60 ;F3., 23.5 .7.5 0.50 *I, F(, F2 and F3 obtained from S2 (32) Table 3 : Nitrogen and protein contents in sampies ofguar gum and its fractions: Sample N. % Protein % ; s, 0.678 4.24 0.732 4.58 I 0,118 0,74 F, 0.049 0.31 F2 0.053 0.33 F3 0.056 0.35 Table 4; pH for samples of gnar gum and its fractions: Sample PH . S,(FSl) 6.70 S2(Fs3) • 6.84 F, 7,00 ' F2 5.90 . F3 ' .5.90 (33) Table 5: The flow time, u, for Fsj and Fs? water - soluble fractions ofsuar sum audits fractions Fu F?.andF\ at 25°C c% Fs, ,.-,- Fs2 F, F2 F3 3 g/ 100cm ts sec. tssec „ . ts sec. ts sec. ts sec. 0.25 70.00 •-- 74.30 71.75 73.20 74.50 0.20 5L80 . .60.00 . 53.00 54.10 78.50 0.15 36.70 38.60" 37.60 38.30 39.10 0.10 25.00 ;; 26.00 25.50 26.00 26.50 0.05 16.50 16.90 16.70 16.95 17.20 Table 6 : The reduced viscosity, n*/C%it, for Fsu Fsjt. Fu F7 and Fi fractions of'euar sum at 25°C: : c% FSl • . Fs2 • •! F.i. ; F2 3 g/100cm T1sp/G% T]Sp/C% Tlsp/C% Tlsp/C% 0.250 20.80 22.30 21.40 21.90 22.35 0.200 17.90 21.50 • 18.45 • 18.95 19.40 0.150 15.00 16.10 15.50 15.95 16.40 ' 0.100 12.10 13.00 12.60 13.00 13.50 : 0.050 09.20 09.90 09.60 10.00 10.50 Table 7: Intrinsic viscosity and molecular weight for fractions of guar sum Sample hldl.g1 Mw g mol"1 : 5 ,FSl ; 6.4 , 7.01xl0 , ; Fs2 . : ' : 6.8 ; 7.62x10' •;. | ;' Fi 6.6 7.31X103 ! F2 7.0 7.93x10' : 5 F3 =• 7.5 : 8.73xlO i (35) Table8: the optical rotation, a°, for waters soluble • • • •: <-...*, •••..• •••-. • - - t-'>_* ||.j • • • •• fractions of guar gum'Fsu Fs?and its fractions FhF7 andFi at 23°C: ; C % , a° • 3 g/100cm ..', FSj; Fs2- F2 F3 ; , ,0.250 0.145 0.1470 0.160 0.165 o.i652 ; 0.200 0.116 0.1180 0.128 '•{ 0.132 ; G.i3oo 0.150 0.088 0.0890 0.096 0.099 0.0975 oaoo 0.058 0.0590 0.064 0.066 0.0650 | 0.050 0.029 0.0295 0.032 0.033 0.0325 ajD > of water-soluble fractions and Fs^ ofguargum and its fractions (25°C) Sample HD Fs, +58° Fs2 +59° F, +64° F2 +66° F3 • +65° (36) l^table JO: Determination of elements contained in samples and fractions of suar sum in % andppm *.•(•;•:. ; it'-' ; • s:, r s2 I •F, | F2; • :;• ;F3- - :•'; % f 0r3l9 0.358 0,2858 0386 0.272 0.280 ' j 0,267. 0.129 0.104 0.115 0.113 0.103 : •tin. ; fpn;ppm ; 33,900,; 41,700 39.900 31.900 38.200 39:800 : •FQ ppm 63,900, 65.500 62.000 56.600 62.500 63:900 ^, *" ppm 51.500 57.500 72.900 61.900 43.800 31.100 ^^- ppm 11.600 14.500 7.750 11.200 10.400 7.390 ; If "'•ppm L460| 1,340. 1,210 1.610 1.680 1.090: ^u 9.960 9.180 11.900 7.570 5.470 4.540 1 ;'t.|P PPm ;]PS ppm 1.010 0.786 0.967 0.600 0.511 0.3-58 ISPP^ : 7.750 8.590 ; 13.100 , 4.190 11.800. ,5.820 jRb ppm 6.670 I 8.720 4.080 L320 1.190 1.230 •v PPm 6.180 6.160 7.720 1.180 1.050 O.S4'2 ^PPm 1.020 1.110 1.360 •, 0.911 0.757 ; i Y 1.320 1.640 1,320 r 0.982 0.797 : PPm i 0.500 0.456 0.310 : ^bppm 0.755 0.731 ' 2.610 1.780 ! 5® ppm I, : (37) illliti ...I i PERCENT^ TRANtSMlTTANCH, L 5 J I 2 mnm- in.: IEITI: •n 3 S I ; • I M I I II J . 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HiJlT J!l T^ 1 =:•.E• = • •,-! rn'r.rn • :!!!! tin! I.:!! 1 I !. W \ I': 11' 1' j! M •. 1 i •.!,•• i >' M I ! I I 11 i; 11 • 1 H • i -i: s i. i i; !Uil M. . L liill :.l Ml- IM ! I ' 1,1 ;: 'I ill •„•. i • 11111 I}I i.::; • i; • • | M l n> '. .'" • I ',: till it $'••-••' o: J l i i iQ I i IIS i ;!^!!i . i i , : ' • t! i 1 P i U.-Uiil! ii'i ..... ! .1! 11.': 1' 1. i: i t.'! 1; • ( • ; I i ; : 1 i-:, j 111I; I1. i ; •:• I ! Ir t i• • ! • • •' •! i i i • ) ; ] ;t I I ; I , I , I . • ii • I • i I . | | : • j._ f i ; : 1 1 i 1 • I1 . i , .! II • • 1 ' : : • : iJ.!MJ.liiil.i:; '" - ::. -.'i! ii' !!•(•ii. ! : j "',;•. ; I.-. ,; • ! .. 11 • i \>-\ '• ii • i 1 , i I I I I , ; I . , . I . ! . I.I i'\! I'-'l': i! ' • I ' : •:'':', ! i I III! 11 I I I i . • i I ' I I ' • ! I L1 I 1 1 I. • I r • -I 1 . • . ( i 1 1 . 1 Ml! 1 I I I I i I I I I i i : I I I '•• • ' ' i iiif l:-i l-'.i •!!•• 1 1 " : : • • : • • ' '"••••!!•' MM i il. uiiMi! 'i; MM •I- I i . ', '. i I I i !• • 1 ' i i 1.'.. •tit tr I If I I I.i i I ' i ' : I I. j I/-!!•!• ' t' i M I ".: • •: i • ' iiii il!. i)i Mil I 1 ,' ' ; 1 -ill'. IJ t. HI! . J.i.sJ. LJJ-t-i- iiii.; IM Ml i.i i i i li UJlji.ii, ii 4.4.1 -ii Mlil-Ll i.u. .1 i t I. . .( ' 1 , • Mm 1 iln. i i :• I : ii !.' n.! I • Tilt -14- •I'l % • fft I! li'.i i-l • i • • i":'l'i t 1 : .I.IM.I... .! il! iJ .:Llilli. J. !:..i lt.i LUILI p. CD (41). 3600 2000 '\500 600 WAVENUMBE8CCMJL Fi&^tO..;.: Theinfrajredspectriim of fraction three (F3) of guar gum Si™iifliii»iirmt^iOTMimMSmM^""™Mfl1iWn)itH??'"ltl^!^ nrrnt-iiin n i Fig. (11): Reduced viscosity (TjSp/C%) versus concentration (C%) for water-soluble fractions Fsi and FS2 of guar gum at 25°C. 25 -1 20 - 15 • 10- 0 0 0.05 0.1 0.15 0,2 0.25 0.3 C%(g/ 100 ml) (43) Fig. (12) : Reduced viscosity (T|sp/C%) versus concentration (C%) for Fi, F2 and F3 fractions of guar gum: at 25°C. 25 - 20 - 15 - 1.0- 0 0.05 0.1 0.15 0.2 0.25 C%(g/100ml) (44) Fig. (13) : Optical Rot^ti^; ctofyersusrcb water1- . 1f . ;\ soluble fractions of guar gum Fsi and Fyi at 25°C. 0.15 -I 0.14 - 0.13 - 0.12 - 0.11 - 0.1 - 0.09 - 0.08 - •Fsl Fs2 0.07 - 0.06 - 0.05 - 0.04 - 0.03 - 0.02 - 0.01 - 0 * 0 0.05 0.1. 0.15 0.2 0.25 C%(g/100ml) (45); ; Fig. (14): Optical Rotation, a°, versus concentration (C%) for Fi, F2 and F3 fractions of guar gum at 25°C. 0.19 - 0.18 - 0.17 - 0.16 - 0.15 - 0.14 - 0.13 - 0.12 - a 0.11 - 0.1- 0.09 - 0.08 - 0.07 - 0.06 - 0.05 - 0.04 - 0.03 - •0.02 - 0.01 - OH 0.05 0.1 0.15 0.2 , 0.25 C% (g/ 100 ml) (46) REFERENCES 1) Howes, F.N.; "Vegetable Gums and Resins"; Chronica Botanica, Waltham, Massachusetts, 1949. 2) Mantell, Ci.; "The Water-Soluble Gums"Hofner Publishing Corp., New York, 1965. 3) Stoloff,L .; Adv. 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