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The study of sugars can be approached from their chemical structure, their properties, their characteristics, or their variety or source. None of these are entirely satisfactory. A discussion of the chemistry and characteristics facilitates the development of an instructional module. However, this is not necessarily a well-rounded view of sugar. Certainly, the sweetness that sugar presents makes an obvious approach to the study of sugars. Fortunately, or unfortunately not all sweeteners are, chemically, sugars. Of the three sensory characteristics; color, texture and flavor, it is easy to focus on flavors as the role of importance. The roles it is apparent that, in addition to sweetness, sugars impact on texture. The question is, how does one make sense of all this? These roles influence the considerations that one must make when selecting a sugar or sweetener. Such considerations that one must make are the desired taste profile of the food the interaction between sugars and/or sweeteners the interaction between sugars and sweeteners and other ingredients the cost of sugars/sweeteners Certainly one can not disregard the role of color. Two phenomena in which sugar plays a major role are the Maillard Reaction and Carmelization. One should not disregard the role of sugars in nutrition. The Revised Dietary Goals (Select Committee on Nutrition and Human Needs, 1977) released by the Senate Nutrition Subcommittee suggests one goal of our population should be a change in food selection and preparation with the U.S. toward a decrease in consumption of refined and other processed sugars and foods high in sugars. A reduction of the "teaspoons of sugar" on your cereal or in your glass of tea is fairly easy to do and, other than flavor, there is not much of a discernible influence on overall quality. However, if one tries to remove sugar as an ingredient and/or replace it with a substitute or alternative, the altered food frequently shows a quality difference. For this reason, in striving towards this proposed U.S. Dietary Goal, it is important to not only consider the role and function of sugar in the diet but also consider those in the food itself. Sugar affects the gelatinization of starch, whether a starch pudding or a high-moisture cake. In either instance, both research and qualitative observations have shown that sugar will delay or inhibit gelatinization of starch. The starch pudding may be less viscose or have a less firm gel. The cake may collapse as the structural contribution of starch is delayed or inhibited. The type of sugar also influences the degree of gelatinization. As seen in the graph the types of sugar impact the degree, temperature and/or speed of gelatinization. Used with Permission Institute of Food Technology The reason for sugars delay upon the gelatinization of starch is still not clear. Generally, researchers indicate that it is likely due to the competition for water. It becomes less clear as to how this competition actually influences the water structure. Does it actually form the "hydrate" structure, does it affect its plasticity or mobility, or does it actually prevent the adsorption of water. Types of Sugar Sugar in most recipes is understood to be granulated sucrose. This sugar usually comes from a cane sugar and sugar beet. However, these last several years, old sources of sugar, engineered and processed sugars, and a new understanding of sugar roles has broadened the knowledge that a food professional should know. There are many types and derivations of sugar types available. More information about sources, processing, and grades of sugar sources is available in the resources section of this site. It is critical to recognize that the type and source of sugars, as well as their granulation will impact the extent of their roles. Frequently, food service personnel and nutritionists, look to the types of sugars and their source. In addition to types, one should look to the granulation and the delivery manner of the sugars. A review of the site will give you some indication of the different types, sources, physical characteristics and affects of sugars. These various sugar sources may have a number of the following sugars. NAME/ CLASSIFICATION ENDPRODUCTS HYDROLYSIS SOURCE, FUNCTION OR CHARACTERISTICS MONO- SACCHARIDES: HEXOSES Glucose glucose fruits, honey, corn syrup Fructose fructose fruits, honey, corn syrup Galactose galactose does not occur in free form in foods Mannose mannose does not occur in free form in foods MONO- SACCHARIDES PENTOSES Ribose ribose derived from pentoses of fruits and nucleic acids of meat products & seafood, does not occur in free forms in foods, is an aldose Xylose xylose is an aldose Arabinose arabinose is an aldose NAME/ CLASSIFICATION ENDPRODUCTS HYDROLYSIS SOURCE, FUNCTION OR CHARACTERISTICS DISACCHARIDES sucrose glucose fructose beet and cane sugars, molasses, maple syrup, comes in many crystal sizes and grades lactose glucose galactose milk and milk products maltose glucose malt products, low concentrations in plants and processed foods

Candies can be divided into two groups, crystalline and noncrystalline. Crystalline candies include fudge, fondant and any other candies which have crystals as an important structural component. Divinity is a crystalline candy but is a special case as the crystals are dispersed in a foam. Noncrystalline candies include caramels, brittles, taffies, marshmallows and gum drops. Marshmallows and gum drops are also special classes of candies as they contain a gelling substance.

Candies are made of sugar (sucrose), water or other liquid and usually some interfering agent(s). Butter, milk, cocoa and corn syrup are commonly used as both crystal interfering agents and flavoring. Candy begins when the water or other liquid is supersaturated with the solute, usually sucrose. Supersaturation occurs when more sugar is present than can be dissolved at that temperature. By heating the solution above the boiling point of water the solute concentration becomes greater. A supersaturated solution is formed when this solution, after heating to a high temperature, is allowed to cool undisturbed. Upon cooling the sugar recrystallizes into several small crystals or forms one large amorphous mass. For crystallization to occur, nuclei must form and solute must be added from the solution to these nuclei. Usually these nuclei form spontaneously but sometimes are "seeded" to the cooked mixture to initiate crystallization. The size of the resulting crystals depends on the number of nuclei, rate and temperature of crystallization, agitation and impurities in the solution.

Crystallization is a complex process with many interrelated factors. The nature of the crystallizing substance is important for crystallization, although not as obvious in candy making as sucrose is almost always the substance under discussion. The rate of crystallization is the speed at which nuclei grow into crystals. This rate is dependent upon the concentration of the solute in the solution as a more concentrated (more supersaturated) syrup will crystallize more rapidly than a less concentrated syrup. At a higher temperature the rate of crystallization is slow and becomes more rapid at a lower temperature. Agitation distributes the crystal forming nuclei and hastens crystallization.

Impurities in the solution usually delay crystallization and in some cases such as caramels may prevent crystal formation. Fat and protein decrease the number and size of crystals through the interference of their masses with the orientation of the sucrose molecules. Corn syrup also has this interfering role; however, additionally it serves to enhance the solubility of sucrose and thus decreases its tendency to crystallize. Cream of tartar as an added ingredient in a candy formula serves indirectly to decrease the rate of crystallization as well as crystal size. It does this through its ability to hydrolyze sucrose into its invert sugar. This not only forms two sugars of greater solubility than sucrose, but it gives agents which enhance the solubility of sucrose.

Inversion of sugars refers to the hydrolysis of sucrose into fructose and glucose to form these sugars which are sometimes referred to as invert sugars. This inversion is thought to take place due to the presence of either enzyme or acid.

The classic example of when we take advantage of this in foods is with chocolate covered cherries. These cherries are made by adding the enzyme invertase to fondant which, as a solid crystalline candy, is placed around the cherries and coated with chocolate. The cherries are allowed to sit and the invertase inside hydrolyzes the sucrose into fructose and glucose. The fructose and glucose combination is much more soluble than the sucrose crystals and so the consumer (eater) perceives a syrup that is very sweet. The reason for the increased sweetness is that fructose is 40-70% greater in sweetness.

There is a whole other category that is referred to as inversion. It is the exciting world which develops the high fructose corn syrup. HFCS is manufactured from corn starch. The cornstarch is hydrolyzed by acid or enzyme and then the resulting glucose is "inverted" into fructose. The percentage will vary. This is one of the "new" processing methods in foods, particularly in the sweetener area.

Acid will hydrolyze and invert the sugars into their component monosaccharides. The implications of this are that any product which has an acid compound may bring about the hydrolysis of sucrose into fructose and glucose. This is particularly true if the product is heated. Fructose and glucose production will bring on a whole series of potential problems in a product. They are reducing sugars, sucrose is not. This means that they will enhance browning. They are more soluble and more hygroscopic than sucrose.

Sweetness
Sweetness is probably the most obvious role of sugar in foods; however, there are a number of others. For example, in candy making the structural role of crystallization is usually critical. In baked products, sugar not only contributes to the browning of the product, but it may serve to tenderize the product through its action on both the gelatinization of starch and denaturation of protein. Before further elucidating the roles and functions of sugar in the various food products it becomes important to be aware of the relative properties of the various sweeteners.

Following are some of the numbers for the relative sweetness of sweeteners and sugars. It is the standard to compare the sweetness of a product to sucrose.

SUGAR AND SWEETENERS	RATING
fructose	140	173	140
HFCS	120-160
sucrose	100	100	100
glucose	70-80	74.3	70-80
70DE corn syrup	70-75	70-75
regular cornsyrup	50
maltose	30-50	32.5	30-50
galactose		32.1
lactose	20	16.0	20
high conversion corn syrup			65
regular conversion corn syrup			50
HFCS-90%			120-160
HFCS-55%			>100
HFCS-42%			100
invert sugar			50
sorbitol			50
xylitol			100
saccharin			30,000-50,000
sucrol [dulcin]			20,000
honey			97
molasses			74
sorghum syrup			69
corn syrup			30
aspartame			180X
Sucralose			600x
Saccharin			300x

Sucrose is 100 and the standard of comparison

What are the practical implications of the varying sweetness?

What do the above sweeteners have in common?

The problem with having a number for sweetness is that it does not take into account the interactions. Powers [Powers, M.A. 1994. Sweetener blending: How sweet it is!. Journal American Dietetic Association 94: 498.] discusses the synergy and interaction between individual sugars and sweeteners. These interactions were summarized as follows:

Permission Pending for Excerpt from Powers, M.A. 1994. Sweetener blending: How sweet it is!. Journal American Dietetic Association 94: 498.

Solubility
Sugars are basically hygroscopic and relatively soluble. This can be seen by the old 1912 reference by Browne. A comparison of sugar to salt shows the tremendous differences between these two type of compounds. A specific review of the relative solubility's between sugars does have tremendous ramifications during food preparation. Generally by reviewing the data from the Chemical Handbook one ranks the order of solubility from the highest through fructose, sucrose, glucose, maltose, galactose, and, least soluble, lactose. Generally, hygroscopcity follows this same ranking. The question becomes, what are the ramifications of this.

Candies are one of the major commodities where the hygroscopicity and solubility, or insolubility, is important.

If you have every gotten a lollipop which was sticky. Very likely the invert sugars [fructose, glucose; corn syrup], which are very hygroscopic, would attract water from the atmosphere.

Effect of Temperature on Solubility of Sucrose, Fructose, and Sodium Chloride (grams per 100 grams water)

TEMPERATURE [C]	SUCROSE [g]	FRUCTOSE [g]	NaCl [g]
0	179.2	.	35.6
10	190.5	.	.
20	203.9	375.0	36.0
30	219.5	.	.
40	238.1	538.0	.
50	260.4	.	.
100	487.3	.	37.8
115	669	.	.

C.A. Browne. 1912. A Handbook of Sugar Analysis, p. 649. John Wiley & Sons.

Name	Formula	Molecular Weight	Solubility in grams per 100 ml of Water
D-Fructose	C6H12O6	180.16	very soluble
D-Galactose	C6H12O6	180.16	10.3 68.3
D-Glucose anhydrous	C6H12O6	180.16	83
Lactose	C12H22O11.H2O	360.31	8
Lyxosee	C6H10O5	150.13	very soluble
Maltose	C12H22O11.H20	360.31	108
D-Mannose	CH2OH(CHOH)4-CHO	180.16	248
Raffinose	CH18H22O16*5H2O	594.52	14
Sucrose	C12H22O11	342.30	179 487
D-xylose	C6H10O6	159.13	117

Handbook of Chemistry and Physics. 41st Edition 1959-1960. Chemical Rubber Publishing Co.

(a gift from my Dad when I entered College)

Melting Point
The melting point of sugars are important from the viewpoint of glassy candies and resulting characteristics. Generally, it is considered to be lower than the point of carmelization.

Name	Formula	Molecular Weight	Melting Point
D-Fructose	C6H12O6	180.16	105C
D-Galactose	C6H12O6	180.16	10.3 118 - 120
D-Glucose anhydrous	C6H12O6	180.16	118-120 anh. 146C
Lactose	C12H22O11.H2O	360.31	-40C
Lyxose	C6H10O5	150.13	106-107
Maltose	C12H22O11.H20	360.31	102.5C
D-Mannose	CH2OH(CHOH)4-CHO	180.16	132C
Raffinose	CH18H22O16*5H2O	594.52	118-Anhydrous
Rhamnose	C6H12O6*H20	182.17	126
Sucrose	C12H22O11	342.30	179C 186
D-xylose	C6H10O6	159.13	153C

Handbook of Chemistry and Physics. 41st Edition 1959-1960. Chemical Rubber Publishing Co.

(a gift from my Dad when I entered College)

Carmelization is the application of heat to the point the sugars dehydrate and breakdown and polymerize. Below is the general word reaction. Carmelization is described as follows by Bennion and Scheule (Introductory Foods, 2000; p. 202).

Caremlization is one type of browning, called nonenzymatic browning because it does not involve enzymes. It is a complex chemical reaction, involving the removal of water and eventual polymerization, and is not very well understood. Caramel has a pungent taste, is often bitter, is much less sweet than the original sugar from which it is produced, is noncrystalline, and is soluble in water. both the extent and rate of the caramelization reaction are influenced by the type of sugar being heated.

Galactose, sucrose and glucose all carmelizes around 160C, but fructose caramelizes at 110C and maltose caramelizes at about 180C.

However, the above reaction is only a broad general brushstroke of this complex reaction. Below is still further step by step detail.

equilibration of anomeric and ring forms

sucrose inversion to fructose and glucose

condensation

intramolecular bonding

isomerization of aldoses to ketoses

dehydration reactions

fragmentation reactions

unsaturated polymer formation

Although a relatively complex reaction, it can be simply done. In the making of peanut brittle, one takes sugar and slowly and carefully heats this in a skillet. It has been found that this slow heating to allow for the uniform "unsaturated polymer formation" occurs best in a heavy cast iron skillet. The brown flavorful peanut brittle is a result of this carmelization process. The presence of sugar acids produced during this process is evident if one wishes to make "foamy peanut brittle". This is produced by taking the heated brown mixture, while still hot, and adding a small amount of baking soda. The reaction of the baking soda with the sugar acids produces carbon dioxide gas which foams. The mixture is quickly poured out into a buttered tray or a solid skillet of peanut brittle will occur.

A number of researchers attribute the carmelization reaction to a range of browning reactions and flavor development. It is only once the melting point has been obtained, sugars will caramelize. Each sugar has its own carmelization temperature.

Maillard Reaction The Maillard reaction is simply the reaction between the amino group of a protein or amino acid and the reducing group of a reducing sugar. It is interesting that the type of sugar and the type of amino acids will impact the "brown" color obtained. The color may range from a yellow to a red. The key here is the reducing sugar. Not all sugars are reducing sugars. Those that are effective reducing sugars are fructose, glucose, maltose, galactose and lactose. Surprisingly, table sugar, or sucrose, is not a reducing sugar.

The affect of sugar upon water activity and shelf life is dependent upon its concencentration and affect upon colligative properties. Certainly, water activity is decreased by adding sugar. As water activity decreases, generally, shelf life increases up to optimum. Remember, water activity not only affects the growth of microorganisms but impacts enzyme activities and oxidative rancidity.

GLOSSARY

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absorption

adsorption

amorphous

amylase

amylopectin

amylose

bacteria

beta-amylase

birefringence

blanc mange

carbohydrate

carbonyl group

cold water-swelling starch(CWS)

colloidal dispersion

complex carbohydrates

corn syrup

covalent bond

crosslinked starch

D.E.

crystalline

crystallization

crystallize

D.E.

dendritic

dextrins

dextrinization

dextrose

enzyme

enzymatic reactions

fermentation

freeze-thaw stability

gel

gelatinization of starch

gelation

gelatinization

glucoamylase

grain size

grind

hilum

hydration capacity

hydrocolloid

implosion

leucoplast

malt processed barley

maltase

Maltese cross

maltodextrins

maltose

milled starch

modified starches

non-reducing end

oxidized starches

pasting

pearl tapioca

polymerization

pregelatinized starch

retorted

retrogradation

roux

retrogradation

starch

starch granule

starch phosphates

syneresis

tapioca

texture

thin-boiling starch

viscosity

waxy starch

whitesauce

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Updated: Wednesday, July 22, 2009.

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