Any reproduction of this material without the express written consent of the American Institute of Baking is prohibited. Sweeteners - Composition, Types, and Functions Definitions Table 1 Sugar Composition In traditional terminology, the word “sugar” has meant table sugar, or sucrose. A wide variety of 6-Carbon or Hexose Monosaccharides Glucose (also called Dextrose) chemical compounds have been found to be sweet tasting, and therefore fall into the category of sweet- Fructose (also called Levulose) ener. The current U.S. definition of sugar, for food Galactose labeling purposes, includes all monosaccharides and disaccharides. As such, sugars are nutritive carbohy- Disaccharides Composed of Source drate sweeteners and are used by the baking industry Sucrose Glucose + Fructose Cane or Beet to add sweetness, flavor, fermentable solids, and Maltose Glucose + Glucose Cereal Starches contribute other physical and chemical properties to Lactose Glucose + Galactose Milk the finished product. The basic building blocks of all sugars are size, and sharpness. Sucrose that is free from invert monosaccharides (one molecule sugars), such as those sugar is hard. Sucrose is obtained from sugarcane, listed in Table 1. Sucrose, lactose, and maltose are sugar beets, certain sorghum plants, 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. esters 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, mineral matter, Sucrose is not directly fermentable by baker’s yeast. 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- enzyme invertase, 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 India. 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 juice is then con- sugar is graded by crystal color, hardness, particle N\archive\communic\cheri\jobfiles\BST-residentcourse-Science\section7\science-sec7.pm65 ©Copyright AIB International Page 1 May not be reproduced without written permission. 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 ©Copyright AIB International Page 3 May not be reproduced without written permission. 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 Powdered Sugar Specifications 6X 10X 12X % Moisture 0.4 0.5 0.5 % Sucrose 97.0 97.0 95.5 % Starch 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 Molasses 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 solution to ing and coloring agent (and humectant) 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 maltodextrin. 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 beet sugar is used both as a sweetener and as a flavoring molasses has a very astringent off-flavor and aroma, agent. The darker the brown sugar 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 enzymes to hydrolyze (split) the sucrose into Table 5 fructose and glucose. Many types of invert syrup are Typical Brown Sugar Specifications available, with medium and total inverts being the most common (Table 6). Invert syrups 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 Honey, 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 proteins, enzymes, organic acids, Table 6 mineral substances, pollen, oils and other substances. Typical Invert Sugar Composition It may additionally include sucrose, maltose, and several oligosaccharides. Nectar from flowers of Medium Total many types is condensed and modified in the bee’s % Moisture 24.0 23.0-23.5 gastrointestinal tract 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.