Đang tải... (xem toàn văn)
Carbohydrates 1 - Principle of food chemistry
INTRODUCTION Carbohydrates occur in plant and animal tissues as well as in microorganisms in many different forms and levels. In animal organ- isms, the main sugar is glucose and the stor- age carbohydrate is glycogen; in milk, the main sugar is almost exclusively the disac- charide lactose. In plant organisms, a wide variety of monosaccharides and oligosaccha- rides occur, and the storage carbohydrate is starch. The structural polysaccharide of plants is cellulose. The gums are a varied group of polysaccharides obtained from plants, seaweeds, and microorganisms. Because of their useful physical properties, the gums have found widespread application in food processing. The carbohydrates that occur in a number of food products are listed in Table 4-1. MONOSACCHARIDES D-glucose is the most important monosac- charide and is derived from the simplest sugar, D-glyceraldehyde, which is classed as an aldotriose. The designation of aldose and ketose sugars indicates the chemical charac- ter of the reducing form of a sugar and can be indicated by the simple or open-chain for- mula of Fischer, as shown in Figure 4-1. This type of formula shows the free aldehyde group and four optically active secondary hydroxyls. Since the chemical reactions of the sugars do not correspond to this structure, a ring configuration involving a hemiacetal between carbons 1 and 5 more accurately represents the structure of the monosaccha- rides. The five-membered ring structure is called furanose; the six-membered ring, pyra- nose. Such rings are heterocyclic because one member is an oxygen atom. When the reduc- ing group becomes involved in a hemiacetal ring structure, carbon 1 becomes asymmetric and two isomers are possible; these are called anomers. Most natural sugars are members of the D series. The designation D or L refers to two series of sugars. In the D series, the highest numbered asymmetric carbon has the OH group directed to the right, in the Fischer projection formula. In the L series, this hydroxyl points to the left. This originates from the simplest sugars, D- and L-glyceral- dehyde (Figure 4-2). After the introduction of the Fischer for- mulas came the use of the Haworth represen- tation, which was an attempt to give a more accurate spatial view of the molecule. Be- cause the Haworth formula does not account for the actual bond angles, the modern con- Carbohydrates CHAPTER 4 Table 4-1 Carbohydrates in Some Foods and Food Products Product Fruits Apple Grape Strawberry Vegetables Carrot Onion Peanuts Potato Sweet corn Sweet potato Turnip Others Honey Maple syrup Meat Milk Sugarbeet Sugar cane juice Total Sugar (%) 14.5 17.3 8.4 9.7 8.7 18.6 17.1 22.1 26.3 6.6 82.3 65.5 4.9 18-20 14-28 Mono- and Disaccharides (%) glucose 1.17; fructose 6.04; sucrose 3.78; mannose trace glucose 5.35; fructose 5.33; sucrose 1.32; mannose 2.19 glucose 2.09; fructose 2.40; sucrose 1 .03; mannose 0.07 glucose 0.85; fructose 0.85; sucrose 4.25 glucose 2.07; fructose 1.09; sucrose 0.89 sucrose 4-1 2 sucrose 12-17 glucose 0.87; sucrose 2-3 glucose 1.5; fructose 1.18; sucrose 0.42 glucose 28-35; fructose 34-41 ; sucrose 1-5 sucrose 58.2-65.5; hexoses 0.0-7.9 glucose 0.01 lactose 4.9 sucrose 18-20 glucose + fructose 4-8; sucrose 10-20 Polysaccharides (%) starch 1 .5; cellulose 1 .0 cellulose 0.6 cellulose 1 .3 starch 7.8; cellulose 1.0 cellulose 0.71 cellulose 2.4 starch 14; cellulose 0.5 cellulose 0.7; cellulose 60 starch 14.65; cellulose 0.7 cellulose 0.9 glycogen 0.10 formational formulas (Figure 4-1) more accurately represent the sugar molecule. A number of chair conformations of pyranose sugars are possible (Shallenberger and Birch 1975) and the two most important ones for glucose are shown in Figure 4—1. These are named the CI D and the IC D forms (also described as O-outside and O-inside, respec- tively). In the CID form of (3-D-gluco-pyra- nose, all hydroxyls are in the equatorial position, which represents the highest ther- modynamic stability. The two possible anomeric forms of monosaccharides are designated by Greek letter prefix a or p. In the oc-anomer the hydroxyl group points to the right, according to the Fischer projection formula; the hydroxyl group points to the left in the p- anomer. In Figure 4-1 the structure marked Cl D represents the oc-anomer, and 1C D represents the p-anomer. The anomeric forms of the sugars are in tautomeric equilib- rium in solution; and this causes the change in optical rotation when a sugar is placed in CHO CHO HCOH HOCH I I CH 2 OH CH 2 OH Figure 4-2 Structure of D- and L-Glyceralde- hyde. Source: From R.S. Shallenberger and G.G. Birch, Sugar Chemistry, 1975, AVI Publishing Co. solution. Under normal conditions, it may take several hours or longer before the equi- librium is established and the optical rotation reaches its equilibrium value. At room tem- perature an aqueous solution of glucose can exist in four tautomeric forms (Angyal 1984): P-furanoside—0.14 percent, acyclic aldehyde—0.0026 percent, p-pyranoside— 62 percent, and oc-pyranoside—38 percent (Figure 4-3). Fructose under the same con- ditions also exists in four tautomeric forms as follows: oc-pyranoside—trace, p-pyrano- side—75 percent, oc-furanoside—4 percent, and p-furanoside—21 percent (Figure 4-4) (Angyal 1976). When the monosaccharides become involved in condensation into di-, oligo-, and polysaccharides, the conformation of the bond on the number 1 carbon becomes fixed and the different compounds have either an all-a or all-p structure at this position. Naturally occurring sugars are mostly hex- oses, but sugars with different numbers of carbons are also present in many products. There are also sugars with different func- Figure 4-1 Methods of Representation of D-Glucose. Source: From M.L. Wolfrom, Physical and Chemical Structures of Carbohydrates, in Symposium on Foods: Carbohydrates and Their Roles, H. W. Schultz, R.F. Cain, and R.W. Wrolstad, eds., 1969, AVI Publishing Co. GLUCOSE(deKtrose) Aldose (oldohexose) Howorth Conformotionol Glucopyronose Glucose Fischer Fischer Figure 4-3 Tautomeric Forms of Glucose in Aqueous Solution at Room Temperature Figure 4-4 Tautomeric Forms of Fructose in Aqueous Solution at Room Temperature tional groups or substituents; these lead to such diverse compounds as aldoses, ketoses, amino sugars, deoxy sugars, sugar acids, sugar alcohols, acetylated or methylated sug- ars, anhydro sugars, oligo- and polysaccha- rides, and glycosides. Fructose is the most widely occurring ketose and is shown in its various representations in Figure 4-5. It is the sweetest known sugar and occurs bound to glucose in sucrose or common sugar. Of all the other possible hexoses only two occur widely—D-mannose and D-galactose. Their formulas and relationship to D-glucose are given in Figure 4-6. RELATED COMPOUNDS Amino sugars usually contain D-glu- cosamine (2-deoxy-2-amino glucose). They occur as components of high molecular weight compounds such as the chitin of crus- taceans and mollusks, as well as in certain mushrooms and in combination with the ovomucin of egg white. Glycosides are sugars in which the hydro- gen of an anomeric hydroxy group has been replaced by an alkyl or aryl group to form a mixed acetal. Glycosides are hydrolyzed by acid or enzymes but are stable to alkali. For- mation of the full acetal means that glyco- sides have no reducing power. Hydrolysis of glycosides yields sugar and the aglycone. Amygdalin is an example of one of the cyan- ogetic glycosides and is a component of bit- ter almonds. The glycone moiety of this compound is gentiobiose, and complete hydrolysis yields benzaldehyde, hydrocyanic acid, and glucose (Figure 4-7). Other impor- tant glycosides are the flavonone glycosides of citrus rind, which include hesperidin and naringin, and the mustard oil glycosides, such as sinigrin, which is a component of mustard and horseradish. Deoxy sugars occur as components of nucleotides; for example, 2-deoxyribose constitutes part of deoxyribonucleic acid. Sugar alcohols occur in some fruits and are produced industrially as food ingredients. Figure 4-5 Methods of Representation of D-Fructose. Source: From M.L. Wolfrom, Physical and Chemical Structures of Carbohydrates, in Symposium on Foods: Carbohydrates and Their Roles, H.W. Schultz, R.F. Cain, and R.W. Wrolstad, eds., 1969, AVI Publishing Co. They can be made by reduction of free sug- ars with sodium amalgam and lithium alumi- num hydride or by catalytic hydrogenation. The resulting compounds are sweet as sug- ars, but are only slowly absorbed and can, therefore, be used as sweeteners in diabetic foods. Reduction of glucose yields glucitol (Figure 4-8), which has the trivial name sor- bitol. Another commercially produced sugar alcohol is xylitol, a five-carbon compound, which is also used for diabetic foods (Figure 4-8). Pentitols and hexitols are widely dis- tributed in many foods, especially fruits and vegetables (Washiittl et al. 1973), as is indi- cated in Table 4-2. Anhydro sugars occur as components of seaweed polysaccharides such as alginate and agar. Sugar acids occur in the pectic sub- Figure 4-6 Relationship of D-Aldehyde Sugars. Source: From M.L. Wolfrom, Physical and Chemical Structures of Carbohydrates, in Symposium on Foods: Carbohydrates and Their Roles, H.W. Schultz, R.F Cain, and R.W. Wrolstad, eds., 1969, AVI Publishing Co. Figure 4-7 Hydrolysis of the Glycoside Amygdalin Benzaldehyde o-Glucose Amygdalin Gentiobiose stances. When some of the carboxyl groups are esterified with methanol, the compounds are known as pectins. By far the largest group of saccharides occurs as oligo- and polysaccharides. OLIGOSACCHARIDES Polymers of monosaccharides may be either of the homo- or hetero-type. When the number of units in a glycosidic chain is in the range of 2 to 10, the resulting compound is an oligosaccharide. More than 10 units are usually considered to constitute a polysac- CH 2 OH HCOH CH 2 OH I I HOCH HCOH I I HCOH HOCH I I HCOH HCOH I I CH 2 OH CH 2 OH Figure 4-8 Structure of Sorbitol and Xylitol charide. The number of possible oligosac- charides is very large, but only a few are found in large quantities in foods; these are listed in Table 4-3. They are composed of the monosaccharides D-glucose, D-galac- tose, and D-fructose, and they are closely related to one another, as shown in Figure 4-9. Sucrose or ordinary sugar occurs in abun- dant quantities in many plants and is com- mercially obtained from sugar cane or sugar beets. Since the reducing groups of the monosaccharides are linked in the glycosidic bond, this constitutes one of the few nonre- ducing disaccharides. Sucrose, therefore, does not reduce Fehling solution or form osazones and it does not undergo mutarota- tion in solution. Because of the unique car- bonyl-to-carbonyl linkage, sucrose is highly labile in acid medium, and acid hydrolysis is more rapid than with other oligosaccharides. The structure of sucrose is shown in Figure 4-10. When sucrose is heated to 21O 0 C, par- tial decomposition takes place and caramel is formed. An important reaction of sucrose, Table 4-2 Occurrence of Sugar-Alcohols in Some Foods (Expressed as mg/100g of Dry Food) Source: From J. Washiittl, R Reiderer, and E. Bancher, A Qualitative and Quantitative Study of Sugar-Alcohols in Several Foods: A Research Role, J. Food ScL, Vol. 38, pp. 1262-1263,1973. Product Bananas Pears Raspberries Strawberries Peaches Celery Cauliflower White mushrooms Arabitol 340 Xylitol 21 268 362 300 128 Mannitol 4050 476 Sorbitol 4600 960 Galactitol 48 which it has in common with other sugars, is the formation of insoluble compounds with calcium hydroxide. This reaction results in the formation of tricalcium compounds C 12 H 22 O 11 -S Ca(OH) 2 and is useful for recovering sucrose from molasses. When the calcium saccharate is treated with CO 2 , the sugar is liberated. Hydrolysis of sucrose results in the forma- tion of equal quantities of D-glucose and D- MANNlNOTRlOSE GALACTOBIOSE MEUBIOSE GAlACTOSE GAtACTOSE GlUCOSE FRUCTOSE SUCROSE RAFFINOSE STACHYOSE Figure 4-9 Composition of Some Major Oligosaccharides Occurring in Foods. Source: From R.S. Shallenberger and G.G. Birch, Sugar Chemistry, 1975, AVI Publishing Co. Table 4-3 Common Oligosaccharides Occurring in Foods Sucrose Lactose Maltose a,oc-Trehalose Raffinose Stachyose Verbascose (a-D-glucopyranosyl p-D-fructofuranoside) (4-O-p-D-galactopyranosyl-D-glucopyranose) (4-O-a-D-glucopyranosyl-D-glucopyranose) (a-D-glucopyranosyl-a-D-glycopyranoside) [O-a-D-galactopyranosyl-(1 ->6)-O-cc-D-glucopyranosyl-(1 ->2)- p-D-fructofuranoside] [O-a-D-galactopyranosyl-(1^6)-O-a-D-galactopyranosyl- (1 -»6)-O-a-D-glucopyranosyl-(1 -»2)-p-D-fructofuranoside] [O-a-D-galactopyranosyl-(1^6)-O-a-D-galactopyranosyl- (1 -»6)-O-cc-D-galactopyranosyl-(1 ->6)-O-oc-D-glucopyrano- syl-(1 ->2)-p-D-fructofuranoside] Source: From R.S. Shallenberger and G. G. Birch, Sugar Chemistry, 1975, AVI Publishing Co. fructose. Since the specific rotation of sucrose is +66.5°, of D-glucose +52.2°, and of D-fructose -93°, the resulting invert sugar has a specific rotation of -20.4°. The name invert sugar refers to the inversion of the direction of rotation. Sucrose is highly soluble over a wide temperature range, as is indicated in Figure 4-11. This property makes sucrose an excellent ingredient for syrups and other sugar-containing foods. The characteristic carbohydrate of milk is lactose or milk sugar. With a few minor exceptions, lactose is the only sugar in the milk of all species and does not occur else- where. Lactose is the major constituent of the dry matter of cow's milk, as it represents close to 50 percent of the total solids. The lactose content of cow's milk ranges from 4.4 to 5.2 percent, with an average of 4.8 percent expressed as anhydrous lactose. The lactose content of human milk is higher, about 7.0 percent. Lactose is a disaccharide of D-glucose and D-galactose and is designated as 4-0-p-D- galactopyranosyl-D-glucopyranose (Figure 4-10). It is hydrolyzed by the enzyme (3-D- galactosidase (lactase) and by dilute solu- tions of strong acids. Organic acids such as citric acid, which easily hydrolyze sucrose, are unable to hydrolyze lactose. This differ- ence is the basis of the determination of the two sugars in mixtures. Maltose is 4-a-D-glucopyranosyl-f5-D- glucopyranose. It is the major end product of the enzymic degradation of starch and glyco- gen by p-amylase and has a characteristic flavor of malt. Maltose is a reducing disac- charide, shows mutarotation, is fermentable, and is easily soluble in water. Lactose CellobTose Maltose Sucrose Figure 4-10 Structure of Some Important Disaccharides TEMPERATURE Figure 4-11 Approximate Solubility of Some Sugars at Different Temperatures. Source: From R.S. Shallenberger and G.G. Birch, Sugar Chemistry, 1975, AVI Publishing Co. Cellobiose is 4-p-D-glucopyranosyl-p-D- glucopyranose, a reducing disaccharide resulting from partial hydrolysis of cellulose. Legumes contain several oligosaccha- rides, including raffmose and stachyose. These sugars are poorly absorbed when ingested, which results in their fermentation in the large intestine. This leads to gas pro- duction and flatulence, which present a bar- rier to wider food use of such legumes. deMan et al. (1975 and 1987) analyzed a large number of soybean varieties and found an average content of 1.21 percent stachyose, 0.38 percent raffinose, 3.47 percent sucrose, and very small amounts of melibose. In soy milk, total reducing sugars after inversion amounted to 11.1 percent calculated on dry basis. Cow's milk contains traces of oligosaccha- rides other than lactose. They are made up of two, three, or four units of lactose, glucose, galactose, neuraminic acid, mannose, and acetyl glucosamine. Human milk contains about 1 g/L of these oligosaccharides, which are referred to as the bifidus factor. The oli- gosaccharides have a beneficial effect on the intestinal flora of infants. Fructooligosaccharides (FOSs) are oligo- mers of sucrose where an additional one, two, or three fructose units have been added by a p-(2-l)-glucosidic linkage to the fruc- tose unit of sucrose. The resulting FOSs, therefore, contain two, three, or four fruc- tose units. The FOSs occur naturally as components of edible plants including banana, tomato, and onion (Spiegel et al. 1994). FOSs are also manufactured com- mercially by the action of a fungal enzyme from Aspergillus niger, p-fructofuranosi- dase, on sucrose. The three possible FOSs are !^(l-p-fructofuranosyl)^ sucrose oli- gomers with abbreviated and common names as follows: GF 2 (1-kestose), GF 3 (nystose), and GF 4 (l F -p-fructofuranosyl- nystose). The commercially manufactured product is a mixture of all three FOSs with sucrose, glucose, and fructose. FOSs are nondigestible by humans and are suggested to have some dietary fiber-like function. Chemical Reactions Mutarotation When a crystalline reducing sugar is placed in water, an equilibrium is established between isomers, as is evidenced by a rela- tively slow change in specific rotation that eventually reaches the final equilibrium val- ue. The working hypothesis for the occur- rence of mutarotation has been described by Shallenberger and Birch (1975). It is assumed that five structural isomers are possible for any given reducing sugar (Figure 4-12), with pyranose and furanose ring structures being generated from a central straight-chain inter- 7. SUGAR [...]... formation of caramelen This compound corresponds to a weight loss of Table 4-5 Reversion Disaccharides of Glucose in 0.082A/ HCI p, p-trehalose (p-D-glucopyranosyl p-D-glucopyranoside) p-sophorose (2-O-p-D-glucopyranosyl-p-D-glucopyranose) p-maltose (4-O-oc-D-glycopyranosyl-p-D-glycopyranose) oc-cellobiose (4-O-p-D-glucopyranosyl-oc-D-glucopyranose) p-cellobiose (4-O-p-D-glucopyranosyl-p-D-glucopyranose) p-isomaltose... (4-O-p-D-glucopyranosyl-p-D-glucopyranose) p-isomaltose (6-O-a-D-glucopyranosyl-p-D-glucopyranose) oc-gentiobiose (6-O-p-D-glucopyranosyl-oc-D-glucopyranose) p-gentiobiose(G-O-p-D-glucopyranosyl-p-D-glucopyranose) 0 .1% 0.2% 0.4% 0 .1% 0.3% 4.2% 0 .1% 3.4% Source: From A Thompson et al., Acid Reversion Products from D-Glucose, J Am Chem Soc., Vol 76, pp 13 0 13 11, 19 54 Figure 4 -1 4 Structure of Isosacchrosan Source: From R.S... Dextrose Equivalent Mono- Di- Acid Acid Acid-enzyme Acid Acid Acid-enzyme Acid-enzyme 1 30 42 43 54 60 63 71 10.4 18 .5 5.5 29.7 36.2 38.8 43.7 Tr /- Tetra- Penta- Hexa- Hepta- Higher 9.3 8.6 13 .9 11 .6 46.2 12 .3 17 .8 13 .2 19 .5 13 .2 28 .1 13.7 36.7 3.7 8.2 9.9 3.2 9.6 8.7 4 .1 3.2 7.2 8.4 1. 8 7.3 6.3 4.5 0.8 6.0 6.6 1. 5 5.3 4.4 2.6 4.3 5.2 5.7 4.3 3.2 45 .1 25.4 29. 51 12.8 8.5 8. 21 7. 61 Includes heptasaccharides... $~Pyranose 64. 0-6 7.9 63. 9-7 0.4 31. 1-3 6.0 68. 4-7 6.0 a-Furanose fi-Furanose 1. 0 3 .1 28. 0- 31. 6 Source: From R.S Shallenberger and G.G Birch, Sugar Chemistry, AVI Publishing Co This indicates that the effect of the hydroxyl ion is about 40,000 times greater than that of the hydrogen ion The rate of mutarotation is also temperature dependent; increases from 1. 5 to 3 times occur for every 1O0C rise in temperature... consists of three distinct stages well separated in time The first step requires 35 minutes of heating and involves a weight loss of 4.5 percent, corresponding to a loss of one molecule of water per molecule of sucrose This could involve formation of compounds such as isosacchrosan Pictet and Strieker (19 24) showed that the composition of this compound is 1, 3'; 2,2'-dianhydro-a-D-glucopyranosyl-p-D-glucopyranosyl-(3-D-fructofuranose... (g /10 0 mL) Water at 2O0C Water at 10 O0C Specific gravity (2O0C) Specific heat Heat of combustion (cal/g ~1) 1 2 0 202 C (dec.) +89.4° 8 70 1. 54 0.299 37 61. 6 ft- An hydride 2520C (dec.) +35° 55 95 1. 59 0.285 3932.7 Values vary with rate of heating, a-hydrate losses H2O (12 O0C) Values on anhydrous basis, both forms mutarotate to +55.4° Source: From R Jenness and S Patton, Principles of Dairy Chemistry, 19 59,... pyranose-pyranose interconversions in the pH range 2.5 to 6.5 Both acids and bases accelerate mutarotation rate, with bases being more effective This was expressed by Hudson (19 07) in the following equation: K250 = 0.0096 + 0.258 [H+] + 9.750 [OH~] Table 4-4 Percentage Distribution of Isomers of Mutarotated Sugars at 2O0C Sugar D-Glucose D-Galactose D-Mannose D-Fructose a-Pyranose 31. 1-3 7.4 29. 6-3 5.0 64. 0-6 8.9... solubility, the a-hydrate crystallizes out and the equilibrium shifts to convert pinto a-hydrate The solubility of the two forms and the equilibrium mixture is represented in Figure 4 -1 6 The solubility of lactose is less than that of most other sugars, which may present problems in a number of foods containing lac- Table 4-6 Some Physical Properties of the Two Common Forms of Lactose Property a-Hydrate 1 Melting... Axis Source: From B.M Smythe, Sucrose Crystal Growth, Sugar Technol Rev., Vol 1, pp 19 1-2 31, 19 71 furanose and pyranose rings are not intersected Lactose can occur in two crystalline forms, the a-hydrate and the p-anhydrous forms and can occur in an amorphous or glassy state The most common form is the a-hydrate (C12H22O 1 1- H2O), which can be obtained by crystallization from a supersaturated solution... glucosan (1, 2-anhydro-oc-D-glucose) and levoglucosan (1, 6-anhydro-p-D-glucose); these have widely differing specific rotation, +69° and -6 7°, respectively These compounds may dimerize to form a number of reversion disaccharides, including gentio- biose and sophorose, which are also formed when glucose is melted Caramelization of sucrose requires a temperature of about 20O0C At 16 O0C, sucrose melts . Conversion Acid Acid Acid-enzyme Acid Acid Acid-enzyme Acid-enzyme Dextrose Equivalent 30 42 43 54 60 63 71 Mono- 10 .4 18 .5 5.5 29.7 36.2 38.8 43 .7 Di- 9.3 13 .9 46 .2 17 .8 19 .5 28 .1 36.7 Tr/- 8.6 11 .6 12 .3 13 .2 13 .2 13 .7 3.7 Tetra- 8.2 9.9 3.2 9.6 8.7 4. 1 3.2 Penta- 7.2 8 .4 1. 8 7.3 6.3 4. 5 0.8 Hexa- 6.0 6.6 1. 5 5.3 4. 4 2.6 4. 3 Hepta- 5.2 5.7 4. 3 3.2 Higher 45 .1 25 .4 29.5 1 12.8 8.5 8.2 1 7.6 1 1 . syrup Meat Milk Sugarbeet Sugar cane juice Total Sugar (%) 14 . 5 17 .3 8 .4 9.7 8.7 18 .6 17 .1 22 .1 26.3 6.6 82.3 65.5 4. 9 18 -20 14 - 28 Mono- and Disaccharides (%) glucose 1. 17; fructose 6. 04; sucrose 3.78; mannose trace glucose. Conversion Acid Acid Acid-enzyme Acid Acid Acid-enzyme Acid-enzyme Dextrose Equivalent 30 42 43 54 60 63 71 Mono- 10 .4 18 .5 5.5 29.7 36.2 38.8 43 .7 Di- 9.3 13 .9 46 .2 17 .8 19 .5 28 .1 36.7 Tr/- 8.6 11 .6 12 .3 13 .2 13 .2 13 .7 3.7 Tetra- 8.2 9.9 3.2 9.6 8.7 4. 1 3.2 Penta- 7.2 8 .4 1. 8 7.3 6.3 4. 5 0.8 Hexa- 6.0 6.6 1. 5 5.3 4. 4 2.6 4. 3 Hepta- 5.2 5.7 4. 3 3.2 Higher 45 .1 25 .4 29.5 1 12.8 8.5 8.2 1 7.6 1 1 Includes heptasaccharides. Source: From