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Sweeteners - Composition, Types, and Functions

Definitions Table 1 Composition In traditional terminology, the word “sugar” has

meant table sugar, or . A wide variety of 6- or (also called Dextrose) chemical compounds have been found to be sweet tasting, and therefore fall into the category of sweet- (also called Levulose) ener. The current U.S. definition of sugar, for labeling purposes, includes all monosaccharides and . As such, are nutritive carbohy- Disaccharides Composed of Source

drate sweeteners and are used by the baking industry Sucrose Glucose + Fructose Cane or Beet to add , , fermentable solids, and Glucose + Glucose contribute other physical and chemical properties to Glucose + Galactose the finished . The basic building blocks of all sugars are size, and sharpness. Sucrose that is free from invert monosaccharides (one sugars), such as those sugar is hard. Sucrose is obtained from , listed in Table 1. Sucrose, lactose, and maltose are sugar beets, certain sorghum , and from the sap disaccharides (two molecule sugars), which are of the American maple tree. If present at equal levels, formed by combining two monosaccharides (bottom there is no difference in sweetening power of sucrose of Table 1). Glucose or dextrose, fructose, sucrose, isolated from different sources. and maltose are the sugars of most interest to bakers. The characteristic aroma and flavor imparted by The structure of common sugars are shown in Figures some sugars is caused by small amounts of certain 1 and 2. contaminating the sugar. There are marked Sucrose differences between the chemical and physical characteristics of these sugars when they are in the raw or partly refined state. These variations result Sucrose is by far the best known of the sugars. from the percentages of invert sugars, matter, Sucrose is not directly fermentable by baker’s . It and nitrogenous organic matter that are contaminants. has to be first hydrolyzed by dilute acids or by the Methods of production, extraction, and purifica- , which will break it down to an tion have become more sophisticated over the hun- equal mixture of fructose and glucose. This mixture is dreds of years that sucrose has been produced, called invert sugar. although the process still resembles what was origi- Although the U.S. government standard for nated in the Middle East and . Clean sugar cane commercial granulated sugar is 99.5% pure, commer- or sugar beets are cut into pieces and mixed with hot cial sugar containing 99.8% sucrose is common. This water to remove the sugar. This is then con- sugar is graded by crystal color, hardness, particle

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Figure 1 Chemical Structure of Common Monosaccharides

Glucose Fructose Galactose

6

5

Glucose 4 1

3 2

Fructose

6

5

Galactose 4 1

3 2

©Copyright AIB International Page 2 May not be reproduced without written permission. Figure 2 Chemical Structure of Common Disaccharides

6

1 5

4 1 2 5 Sucrose

3 2 3 4 6

Glucose Unit Fructose Unit

6 6

5 5

Maltose 4 1 4 1

3 2 3 2

Glucose Unit Glucose Unit

6

3 2 5

Lactose 4 1 4 1

3 2 5

6 Galactose Unit Glucose Unit

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Table 2 Typical Bakers Special Sucrose Specifications

Supplier #1 Supplier #2 Supplier #3 % Moisture 0.03 0.02 0.03 % Sucrose 99.995 99.95 99.92 % Invert 0 0.01 0.02 % Ash 0.015 0.01 0.01

Screen Analysis % Over US 50 4.0 3.0 Less than 2 % Over US 70 45.0 — — % Thru US 140 4.0 Maxiumum 20 — & Thru US 200 — — Less than 5

Table 3 Typical Specifications

6X 10X 12X % Moisture 0.4 0.5 0.5 % Sucrose 97.0 97.0 95.5 % 3.0 3.0 4.5

Screen Analysis % Over US 70 < 0.5 <0.5 <0.01 % Over US 100 — <0.15 — % Thru US 200 91.5-97.5 >97 99.5 & Thru US 325 — — 98.5

Table 4 Typical Composition

Imported First Third Final % Solids 79.5 79.5 79.5 79.5 % Sucrose 35 34 36 34 % Invert 39 37 26 19 % Total Sugars 74 71 62 53 % Ash 2.0 2.3 5.6 9.5

pH 4.8 5.0 5.0 5.0

Color 0.2 0.3 0.8 1.5

From AIB Technical Bulletin June 1996, Joseph Hickenbottom.

densed, filtered, refined, and allowed to crystallize special is very uniform in crystal size, smaller than several times until it is sufficiently purified. typical table sugar (Table 2). Dry sucrose products are classified according to Powdered sugars are pulverized crystalline granulation. The coarsest available sugars are the sucrose, ranging in categories from 2X to 12X (Table “sanding” or coarse granulated, with the regular or 3). The higher the number assigned, the smaller the medium granulation being typical table sugar. Bakers particle size (more grinding applied). Because of the

©Copyright AIB International Page 4 May not be reproduced without written permission. large surface area created by grinding powdered mill molasses, varying in the number of crystalliza- sugars, they are very hygroscopic. Therefore, dried tions through which the liquor has gone (Table 4). starch or tricalcium phosphate is often added as a flow The lower the molasses grade (higher number), the agent, to prevent water pickup and caking of the smaller the amount of total sugars remaining. There- sugar. fore, the highest grade (first molasses) has the most Fondant sugar is the smallest particle size of total sugars present, is lightest in color, and has the sucrose available to the baker. Paste fondant is least flavor. Molasses is often used more as a flavor- prepared by heating a concentrated sucrose to ing and coloring agent (and ) than as a boiling, then cooling gradually with controlled mixing sweetening agent. such that the sucrose crystallizes as very fine particles Brown sugars contain a small percentage of invert suspended in a saturated sucrose solution. Dry sugar and moisture in addition to sucrose. Historically fondant is manufactured by blending a finely ground they were sugars that had received less refinement. sucrose with invert sugar or . Today brown sugars are made by addition of molasses Molasses is the concentrated juice (liquor) ex- to refined sugar. This allows a better control of tracted from sugar cane, containing naturally occur- composition and particularly color (Table 5). Brown ring substances in addition to sucrose. sugar is used both as a sweetener and as a flavoring molasses has a very astringent off-flavor and aroma, agent. The darker the the stronger the and is not generally used in food applications. Be- flavor it carries. The storage conditions for brown cause of the many variables involved in producing sugar must be controlled to avoid formation of hard molasses, it can fluctuate widely in flavor and compo- lumps in the product. Optimum conditions are 65- sition. Sun-ripened sugar cane grown in the Carib- 70% relative humidity. If brown sugar is exposed to bean area is pressed and clarified (but not otherwise low relative humidity the surface molasses tends to processed) into what is called imported molasses. It is dehydrate, crystallize, and eventually form hard subjected to controlled curing and maturing; resulting lumps. Bagged brown sugar also should not be stored in a premium grade molasses in terms of its light in large stacks, to prevent compression of the bottom color, mellow flavor, mild aroma, high sweetness, and layers, another cause of lumps. clarity. Imported unsulphured molasses is also called cane juice molasses. Mixed Sugars U.S. sugar cane is processed into several grades of Invert sugar is made by treating sucrose with acid and/or to hydrolyze (split) the sucrose into Table 5 fructose and glucose. Many types of invert are Typical Brown Sugar Specifications available, with medium and total inverts being the most common (Table 6). Invert are used for Light Dark their humectancy, although they are generally being % Moisture 2.5-4.0 2.5-4.0 replaced by high fructose corn syrups. % Sucrose 89-94 86-90 , often called nature’s invert syrup, is by far % Invert 1.25-3.25 2-5 the oldest sweetener used by man. However, the % Total sugars 91-96 91-64 glucose:fructose ratio is not 1:1 and even varies between sources (Table 7). As the fructose content increases, crystallinity problems decrease. In addi- tion, honey contains , enzymes, organic acids, Table 6 mineral substances, pollen, oils and other substances. Typical Invert Sugar Composition It may additionally include sucrose, maltose, and several . from flowers of Medium Total many types is condensed and modified in the bee’s % Moisture 24.0 23.0-23.5 and stored in their hives, from % Sucrose 30-35 <3 which it is collected. Honey is sold by grade, based % Invert 41-46 73.5 on the floral source of nectar, which impacts the % Ash 0.01-0.02 0.01-0.02 flavor and color. Honey is used in specialty products pH 3.8-4.2 3.8-4.2 where specific flavor and aroma characteristics are

©Copyright AIB International Page 5 May not be reproduced without written permission. Corn Syrups (Glucose Syrups) Table 7 Typical Honey Composition Corn syrups are derived from cornstarch, a

readily available source of glucose (long % Moisture 18.3 % Fructose * 41 strings of glucose or dextrose sugars). Glucose % Glucose * 34 syrups can be produced from any starch source. The % Sucrose 2.42 discovery that starch could be converted into a sweet * Fructose:Glucose ratio varies liquid by heating in dilute acid was made in a Russian laboratory in the early 1800’s. The first US for manufacturing cornstarch was opened in 1866,

producing up to 42 DE , although modern Table 8 enzymatic methods have made 95 DE corn Dextrose Equivalents syrups possible. Various enzymes can convert gelatinized 10 100 starch into , maltose, and dextrose. Properties Purified enzymes do not have side reactions and by Solid Syrup choosing the correct enzyme or enzymes specific High Low viscosity sugars can be produced. (small fragments of Not sweet Sweet starch) and maltose are produced using a mixture of Nonfermentable Fermentable primarily α- and β-amylase. A mixture of pullulanase Low osmotic pressure Highly osmotic (a debranching enzyme) and β-amylase will produce an almost pure maltose syrup. The enzyme Functional Uses amyloglucosidase (glucoamylase) will produce a Bodying agent Browning agent syrup containing essentially all glucose (>95%). Cohesive agent Flavor enhancer (DE), a measure of the Foam stabilizer Freezing point depression percentage of glucosidic bonds in starch that have Prevent ice crystal been hydrolyzed, refers to the level of reducing growth Flavor transfer medium sugars present in the glucose or corn syrup. DE tells Prevent sugar us how many of the bonds are broken but does not Hygroscopic tell anything about which sugars are produced. Commercial corn or glucose syrups contain dextrose (or glucose), maltose, and varying quantities of desired. For that reason, bakers’ honey is usually

stronger flavored and darker than table honey. extracts or malt syrups are viscous concen- Table 9 trates of the water extract of malted , generally Typical Corn or Composition . The predominant sugar is maltose, although some glucose and larger oligosaccharides will be 36 DE 42 DE 62 DE 95 DE present. Malt syrups are either diastatic (enzyme % Solids 80 80.3 83 71 active) or nondiastatic (enzyme inactive). The pH 4.7 4.7 4.7 4.5 primary enzymes of interest in malt syrups are the Dry Basis Composition , particularly α-amylase, although many %Glucose 15 19 39 92 other enzymes such as protease are also present. % Maltose 12 14 28 3 Nondiastatic malt has been heated to inactivate the % 11 12 14 1 enzymes, and is used for flavor. Diastatic malt adds %Higher saccharides 62 45 19 4

flavor and supplements any α-amylase deficiency in the flour. higher saccharides with varying degrees of - ization. The higher the level of mono- and disaccha- rides the sweeter the syrup and the higher the DE (Table 8). Dextrose has a DE of 100 and starch has a DE of 0.

©Copyright AIB International Page 6 May not be reproduced without written permission. Combining enzyme technology with acid hydroly- Table 10 sis, manufacturers are able to produce a wide variety Typical High Fructose of DE corn syrups or glucose syrups (Table 9). The (Corn) Syrup Specifications lower DE corn syrups (36-62 DE) are used primarily for added texture and body, such as in chewy cookies 42% 55% 90% and creme fillings. Higher DE syrups (62-95 DE) are % Solids 71 77 80 added for sweetness and fermentability. Dry Basis Composition None of the common corn syrups are as sweet as % Glucose 52 41 7 sucrose. When 95 DE corn syrup is exposed to the % Fructose 42 55 90 enzyme glucose isomerase, under controlled condi- % Higher Saccharides 6 4 3 tions, some of the glucose is converted to fructose, resulting in a sweeter syrup (Table 10). Storage conditions of all corn or glucose syrups Table 11 must be carefully regulated to minimize crystalliza- Recommended Syrup Storage Temperatures tion and browning (Table 11, Figures 3 and 4). As with honey, the higher the glucose content, the more Storage Temperature readily crystallization will occur. °F °C Commercial dextrose was initially solidified high 42 DE 90-100 32-38 DE corn syrup, sold as corn sugar. Dextrose has the 62 DE 90-100 32-38 unique ability to produce a cooling sensation as it 95 DE 130 54 dissolves on the , because of its negative heat 42% HFCS 80-85 27-29 of solution. Bakers dextrose is actually crystalline 55% HFCS 80-85 27-29 dextrose monohydrate (Table 12). Products vary only 90% HFCS 70-80 21-27 in particle size. Finer granulation is preferred for use Medium Invert 90 32 in icings and creme fillings, the major applications for dextrose.

Figure 3 Effect of Temperature on Color of 42% High Fructose Corn Syrup

110OF(43OC) 100OF (38OC) Color, CIRF x 100 90OF(32OC) 80OF (27OC)

01 23 4 56 789 Storage (Weeks)

From: AIB Technical Bulletin, June 1984.

©Copyright AIB International Page 7 May not be reproduced without written permission. Figure 4 Lactose Effect of Temperature on Corn Syrup Viscosity The only readily available sugar not from plant 700 material is lactose, which is from milk. Dried , which is more than 70% lactose, is the source of 600 most purified lactose. Milk, milk powder, and whey are the common forms of lactose used in bakeries. Lactose is a with very little sweet- 500 ness, and is not fermentable. Thus, it is used as a browning agent when additional sweetness is not 400 E desirable.

300 Sweetness

A comparison of the sweetness level of many 200 common sweeteners is given in Table 13. Sucrose is C always given a rating of 100. However, sweetness is Viscosity (Poises) 100 a , and varies between people and between matrices (food system - what else is with the sweet- 50 ener). The values given are therefore relative and not “set in ”. B 25 % MoistureA 8.5 Table 13 0 % Glucose 91.4 Sweetness Ratings 80 100 120 140 O % Ash 0.03 F ppm 27 38 49 2 60 OC Sweetener Rating(1)(2) DE >99.5 Sucrose 100 A - 42% High Fructose Corn Syrup Dextrose (glucose) 80 B - 55% High Fructose Corn Syrup Fructose 140 C - 62 % DE Corn Syrup Maltose 40 E - 42 % DE Corn Syrup Lactose 20 Galactose 32 From: AIB Technical Bulletin, June 1984. Invert sugar (medium) 120 Invert sugar (total) 130 Molasses 70-90 42 DE corn syrup 40 Table 12 62 DE corn syrup 70 Typical Dextrose Composition 95 DE corn syrup 80 42% HFCS 100 55% HFCS 110 90% HFCS 140 (1) Based on sucrose as 100 (2) Syrup sweetness on a dry solids basis

©Copyright AIB International Page 8 May not be reproduced without written permission. Alternative Sweeteners Table 14 Alternative Sweeteners Consumers are often looking for food products with decreased levels of , sugar, and , and Product Sweetness(1) Calories(2) bakery products are no exception. Legal status High Intensity changes regularly, and varies between countries. 30,000 0 Therefore, always check before including any of Cyclamate 3,000 0 these sweeteners in your baked product. 200,000 0 Several options exist to replace the sugar in food 16,000-22,000 4 products, including high-intensity or non-nutritive 60,000 0 sweeteners (top of Table 14). All sugar substitutes Acesulfame K 20,000 0 that are rated sweeter than sucrose will be used in 200,000-300,000 4 much lower quantity than sucrose, so that even if the caloric value is not 0, the total caloric contribution Bulking will be less than if sucrose were used. Bulking agents 100 2.4 are often used to replace some of the nonsweetening 90 2.1 functions of sugar. 50-70 2.6 Another option for bakers is to use bulking 50-70 1.6 sweeteners. Most of this category is made of sugar 30-40 2.0 , also called or polyalcohols (bottom Hydrogenated starch 25-75 3.0 of Table 14). Polyols are derived from sugars by hydrolysates hydrogenation of the sugar molecule, reducing the carbonyl group to an or hydroxyl group. (1) Sweetness compared to sucrose = 100 Because they have some caloric value, bulking (2) Calories/gram (sucrose = 4) sweeteners are considered nutritive sweeteners. Sugar substitutes vary in heat stability, off- , and other characteristics, so careful research must be done before changing ingredients.

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