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clean sweet taste with no unpleasant aftertaste. It is

blended with other sweeteners such as, saccharin,

cyclamate, and acesulfame-K to maximize the quality

of sweetness.

0008 Alitame offers several benefits such as stability at

high temperatures and a broader pH range. For in-

stance, it is stable for over a year at pH 6–8 and room

temperature and withstands pasteurization. How-

ever, prolonged storage of acidic solutions at high

temperatures or in combination with certain ingredi-

ents (hydrogen peroxide or sodium bisulfite) may

produce off-flavors. In the presence of high levels of

reducing sugars, alitame can undergo Maillard reac-

tions.

0009 Alitame is noncariogenic. From an oral intake,

7–22% is unabsorbed and excreted in the feces.

The remainder is hydrolyzed to aspartic acid and

alanine amide. The aspartic acid is normally

metabolized, and the alanine amide is excreted

in the urine as a sulfoxide isomer, sulfone, or con-

jugated with glucuronic acid. The incomplete ab-

sorption and metabolism result in a core value of

1.4 kcal g

1

0010The Joint Expert Committee on Food Additives

(JECFA) concluded that alitame was not carcinogenic

and did not show reproductive toxicity. In 1996, an

acceptable daily intake (ADI) of 0–1 mg per kilogram

of body weight was allocated. It is approved for use in

Australia, New Zealand, Mexico, and China. A food

additive petition was submitted to the US Food and

Drug Administration (FDA) in 1986, and approval is

awaited. In the petition, the estimated daily intake

is 0.34 mg per kilogram of body weight, which re-

presents the amount if alitame is the only sweetener

in the diet. The level at which no observed adverse

effects occur in animals is 100 mg kg

1

. Potential uses

include baked goods, baking mixes, hot and cold

beverages, dry beverage mixes, table-top sweet-

eners, chewing gum, candies, frozen desserts, and

pharmaceuticals.

Sucralose

0011Sucralose, 1,6-dichloro-1, 6-dideoxy-b-d-fructofura-

nosyl 4-chloro-4-deoxy-a-d-galacto-pyranoside or

4,1

-trichloro-4,1

-trideoxy-galacto-sucrose

(Figure 2), is a chlorinated derivative of sucrose, dis-

covered in 1976 by carbohydrate research chemists at

Queen Elizabeth College and Tate and Lyle, UK. It is

derived from a patented multistep process, involving

selective chlorination of sugar at the 4, 1

, and 6

positions substituting three hydroxyl groups on the

sucrose molecule. It is the result of a study on a large

number of related compounds, carefully synthesized

and evaluated to determine the spatial structure

and molecular configuration required for sweetness

perception.

0012Ingredients and tabletop forms of sucralose are

being marketed under the brand name Splenda

. Its

chemical formula is C

(MW 397.35).

Sucralose is a white, odorless crystalline powder and

is readily dispersible and soluble in water, methanol,

and ethanol. At 20



C, a 280 g l

1

solution of sucra-

lose in water is possible. Sucralose presents Newton-

ian viscosity characteristics, a negligible lowering of

surface tension, and no pH effects, and its solubility

increases with increasing temperature. In ethanol, the

solubility ranges from approximately 110 g l

1



C to 220 g l

1

at 60



C, and its solubility in etha-

nol facilitates in formulating alcoholic beverages and

flavor systems.

fig0005 Figure 5 Chemical structure of the sweet glycoside of Stevia

rebaudiana Bert.

COOH

fig0004 Figure 4 Chemical structure of glycyrrhizin.

SWEETENERS/Others 5697

tbl0001 Table 1 Properties of some intense sweeteners

Sweetener (INS)

Sweetness

Sweetness characteristics Synergism

Solubilityin water Stability ADI

(mgper kilogram of

body weight)

In solution During heating

Alitame 2000 Clean, no unpleasant aftertaste sac, cyc, aces Good, 130 g l

1

, pH 5.6 Good, pH 6–8 Very good 0–1 (1996)

Sucralose (955) 400–800 slow onset, clean sweet sugar-

like, prolonged sweetness

cyc, aces, nhdc Good, 280 g l

1

,20



C Good, pH > 3, loss of

sweetness, pH < 3

Very good 0–15 (1990)

Neohesperidin

dihydrochalcon (959)

250–2000 delayed onset, lingering

licorice–menthol-like

aftertaste

sac, asp, aces,

cyc, sucral,

sugar alcohols

Low, 0.5 g l

1

,20



650 g l

1

,80



Stable, pH 2–6 Good Not evaluated by JECFA,

0–5 (1987–SCF

, EC)

Glycyrrhizin (958) 50–100 Slow onset, long aftertaste,

licorice flavor

stev, thau, asp Good Stable, pH > 4.5 Good Not evaluated by JECFA

Stevioside 100–300 Slow onset, menthol at high

levels, bitter

asp, cyc, aces,

glyc

Low, 0.8 g l

1

Stable, pH 3–10 Good Not evaluated by JECFA

Thaumatin–Talin (957) 2000–3000 Slow onset, persistent, licorice-

sac, aces, asp,

cyc, stev, glyc

Good, 600 g l

1

Stable, pH 2.7–6.0 Stable, neutral

to low pH

Not specified (1985)

INS, International Numbering System.

In relation to sucrose.

sac, saccharin; cyc, cyclamate; aces, acesulfame-K; nhdc, neohesperidin dihydrochalcone; asp, aspartame; sucral, sucralose; stev, stevioside; thau, thaumatin; glyc, glycyrrhizin.

SCF, Scientific Committee for Food.

From Glo

ria MBA (2000) Intense sweeteners and synthetic colorants. In: Nollet LML (ed.) Food Analysis by HPLC, pp. 523–573. New York: Marcel Dekker.

0013 Sucralose is 400–800 times sweeter than sucrose

(Table 1). Although its sweetness varies with pH,

sucralose has a clean sugar-like taste and a time–

intensity profile like that of sucrose, albeit more per-

sistent. It has an excellent taste profile and no bitter

or objectionable aftertaste. It is a flavor enhancer and

shows sweetness synergism with cyclamate, acesul-

fame-K, and neohesperidin dihydrochalcone.

0014 Sucralose offers a broad pH, aqueous, thermal

processing, and shelf stability. It does not interact

with food ingredients and is stable in the dry form

(4 years at 20



C). It withstands high temperatures,

thus making it well suited for use in pasteurized,

aseptic processing, sterilized, cooked, and baked

foods. However, under extreme conditions of pH,

temperature, and time, sucralose may be hydrolyzed,

producing 4-chloro-deoxy-d-galactose and 1,6-

dideoxy-1,6-dichloro-d-fructose, or degraded with

elimination of hydrogen chloride in basic medium.

0015 Sucralose is noncariogenic. It resists hydrolysis in

the human digestive tract, being excreted unchanged

in the feces, and the very small portion absorbed is

rapidly eliminated in the urine. Therefore, it produces

no glycemic response and is virtually noncaloric.

Following safety testing and toxicological studies in

humans and animals, the FDA concluded that sucra-

lose does not pose any carcinogenic, reproductive, or

neurological risk. The JECFA reviewed it favorably

and in 1990 recommended an ADI of 0–15 mg per

kilogram of body weight. Sucralose is approved for

use in a wide range of food products in Canada, USA,

Australia, Mexico, Russia, Romania, China, the

European Union, and Mercosur. It has been used as

a table-top sweetener and in carbonated, still, and

alcoholic beverages, frozen desserts, confectionery,

bakery products, canned fruits and vegetables, fruit

spreads, chewing gum, dry-mix products, dairy prod-

ucts, condiments, dressings, and breakfast cereals.

Neohesperidin Dihydrochalcone

0016 Citrus fruits contain bitter flavanone glycosides, all

derivatives of the disaccharide 2-O-a-l-rhamnopyra-

nosyl-b-d-glucopyranose, neohesperidose. In 1963,

Horowitz and Gentili found that catalytic hydrogen-

ation of the chalcone form gave dihydrochalcone

neohesperidosides, several of which were intensely

sweet. Numerous dihydrochalcone derivatives were

synthesized for taste and toxicity trials, from which

neohesperidin dihydrochalcone (NHDC) emerged as

a promising sweetener. It is prepared by alkaline hy-

drogenation of the biflavanoid neohesperidin present

in Seville (bitter) oranges (Citrus aurantium).

0017 NHDC is a semisynthetic nonnutritive intense

sweetener. Chemically, it is 1-[4-[[2-O-(6-deoxy-a-l-

mannopyranosyl)-b-d-glucopyranosyl]oxy]-2,6-

dihydroxyphenyl]-3-(3-hydroxy-4-methoxyphenyl)-

1-propanone with the molecular formula C

and a molecular weight of 612.60 (Figure 3). NHDC

shows a slow buildup of sweetness, rising from 250 to

2000 times that of a 50 g l

1

sucrose solution, but

more persistent (Table 1). It has a pleasant taste,

flavor-modifying properties, ability to improve the

sweetness quality and profile, and remarkable syner-

gistic effects. Its flavor enhancement has been per-

ceived in several products, specially fruit flavors.

NHDC has the ability to decrease the perception of

bitterness, saltiness, sharp, and spicy attributes. The

sweetness intensity of NHDC depends on many

factors such as concentration, pH, and the product

to which it is added. As the concentration increases,

the sweetness of NHDC decreases relative to the level

of sucrose. Caffeine significantly enhances the sweet-

ness of NHDC in certain soft drinks. At higher con-

centrations, NHDC has a lingering menthol or

licorice-like aftertaste and a cooling sensation,

which distinguishes it from other sweeteners. How-

ever, modifications of the sensorial properties of

NHDC are possible by the admixture of bulk sweet-

eners, certain flavors, and other taste-modifying food

additives such as gluconates, amino acids, or nucleo-

tides. It also shows synergism with saccharin, aspar-

tame, cyclamate, sucralose, acesulfame-K, and sugar

alcohol.

0018NHDC is a nonhygroscopic colorless crystalline

solid. It is sparingly soluble in water (0.50 g l

1

)at



C but is highly soluble at 80



C (650 g l

1

). It is

also soluble in alcohol and aqueous alkali, but a

higher solubility is achieved in ethanol–water mix-

tures than in water or ethanol alone. Where a higher

solubility is required, monobasic salts may be used

that are freely soluble in water and exhibit a shorter

duration of sweetness than the parent compound. The

solubility of NHDC may also be enhanced by dissolv-

ing it in glycerol and propylene glycol, as well as by

using it in mixtures with readily water-soluble polyols

such as sorbitol. Interestingly, these bulk sweeteners

also act as taste modifiers of NHDC by reducing its

menthol-like aftertaste.

0019NHDC presents high stability at pH 2–6. It is

stable under most food-processing and storage condi-

tions and withstands pasteurization, UHT processes,

and the normal shelf-life of soft drinks. It is stable

during fermentation of yogurt, but undergoes hy-

drolysis at high acidity and elevated temperatures,

yielding hesperetin dihydrochalcone, hesperetin

dihydrochalcone-4

-b-d-glucoside, rhamnose, and

glucose.

0020NHDC is noncariogenic and has a caloric value

of 2 kcal g

1

. Little of the compound is absorbed

SWEETENERS/Others 5699

unchanged from the small intestine. After cleavage of

the glycosidic side-chain by intestinal mucosal or bac-

terial glycosidases, the residual primary metabolites

are partly excreted unchanged in the bile and partly

metabolized further. Standard toxicity tests have sug-

gested its safety. In 1987, the Scientific Committee for

Food of the Commission of the European Commu-

nities allocated an ADI of 0–5 mg per kilogram of

body weight. It is currently approved for use in the

European Communities, Sweden, Switzerland, Mo-

rocco, and Tunisia.

0021 Owing to its highly intense and long-lasting sweet-

ness, NHDC is normally used at concentrations of

less than 100 mg kg

1

. Only in chewing gum are

higher levels required because of its slow release

from the gum base. For use in soft drinks, NHDC

has been recommended in combination with other

sweeteners at a concentration of 20 mg kg

1

. Owing

to its ability to reduce bitterness and to its flavor

enhancing properties, NHDC is an ideal sweetener

for grapefruit or orange juice. Promising results

have been reported from its use in fruit-flavored

yogurts. In table-top products, the addition of small

amounts of NHDC may result in significant savings

because of its synergistic, sweetness enhancing effect.

It has been used in juice, soft drinks, dairy products,

desserts, confectionery, spreads, jams, chewing gum,

chocolate based products, and icecream.

Glycyrrhizin

0022 Glycyrrhizin is found in licorice root of a small leg-

uminous shrub, Glycyrrhiza glabra L. from Europe

and Central Asia. Glycyrrhizin or 20-b-carboxy-11-

oxo-30-norolean-12-en-3b-yl-2-O-b-d-glucopyranu-

rosyl-a-d-glucopyranosiduronic acid (C

MW 822.92), is a triterpenoide glycoside (saponin)

with glycyrrhetinic acid, which is condensed with

O-b-d-glucuronosyl-(1

!2)-b-d-glucuronic acid

(Figure 4). After harvest, the roots are dried to 10%

moisture, shredded, extracted with aqueous ammo-

nia, concentrated in vacuum evaporators, precipi-

tated with sulfuric acid, and crystallized with 95%

alcohol providing a crude ammonium glycyrrhizin

(AG). Further treatment yields a white, crystalline

mono-ammonium glycyrrhizin (MAG). Both deriva-

tives have the same sweetness but differ in solubility

and sensitivity to pH. AG is relatively stable and

highly soluble in hot or cold water and in alcohol. It

withstands temperatures above 105



C for a short

period of time, and precipitates at pH values below

4.5. MAG is used in applications where low pH and

color rule out AG.

0023 Glycyrrhizin is 50–100 times sweeter than sucrose

and has a slow onset of sweetness followed by a

lingering licorice-like aftertaste (Table 1). It exhibits

a sweet woody flavor, which limits its use as a pure

sweetener. Glycyrrhizin enhances food flavors, masks

bitter flavors, and increases the perceived sweetness

level of sucrose. It has the potential for providing

functional characteristics, including foaming, viscos-

ity control, gel formation, and possibly antioxidant

characteristics.

0024Studies have focused on the pharmacological

effects of glycyrrhizin as antiulcer, antiinflammatory,

antiviral, anticariogenic, and antispasmodic. It also

has corticoid activity, influencing steroid metabolism

to maintain blood pressure and volume and to regu-

late glucose/glycogen balance. Glycyrrhizin can be

hydrolyzed by human intestinal microflora to 18-b-

glycyrrhetinic acid and two molecules of glucuronic

acid. After release of the acids, the compound binds

to plasma protein, enters the enterohepatic circula-

tion, and is almost completely metabolized. However,

side-effects, typically involving cardiac dysfunction,

edema, and hypertension have been reported among

subjects receiving high doses of glycyrrhizin-based

pharmaceuticals or consuming large amounts of lic-

orice-containing confectionery or health products

over a prolonged period.

0025The ammonium salt of glycyrrhizin is approved as

a flavoring and flavor enhancer in the USA. It is on

the FDA ‘generally recognized as safe’ (GRAS) list.

The use of glycyrrhizin is permitted in Japan and

Taiwan. In Japan, it is used as a flavoring for hydro-

lyzed vegetable protein, soy sauce, and bean paste to

control saltiness. At levels of 30–300 mg kg

1

, it en-

hances the flavor of cocoa and chocolate-flavored

products, flavors and sweetens candy, confectionery,

and beverages, and masks the bitter taste of pharma-

ceuticals. Because of its pharmacological action, it

should be used in moderate amounts as a sweetener.

Stevia Sweeteners

0026Stevia rebaudiana Bertoni (Compositae) is a herb

native to Paraguay but cultivated in South-east Asia,

Japan, Paraguay, Brazil, Israel, and USA. Stevia

sweeteners are extracted from the dried leaves, clari-

fied and crystallized. The sweet constituents of stevia

include eight diterpene glycosides: stevioside, steviol-

bioside, rebaudiosides A, B, C, D, and E, and dulco-

side A, which collectively are 100–300 times sweeter

than sucrose. They are similar in structure in that a

steviol aglycon is connected at C-4 and C-13 to

mono-, di-, or trisaccharides consisting of glucose

and/or rhamnose residues, as shown in Figure 5.

Stevioside is the major constituent, whereas dulcoside

A and rebaudiosides A and C are the other main

components. Stevioside is 300 times sweeter than

5700 SWEETENERS/Others

sucrose (Table 1). It shows a sweetness profile similar

to that of sucrose, except that it has an unpleasant,

persistent, menthol, and bitter aftertaste. However,

the development of new cultivars, derivatization and

incorporation of cyclodextrin, l-histidine, potassium

phosphate, glucono-d-lactone and maltose in formu-

lations has eliminated undesirable aftertastes. Rebau-

dioside A is more stable, sweeter, and has a better

taste profile than stevioside. The remaining diterpene

glycosides are not as sweet as stevioside.

0027 Stevioside is a white powder, highly soluble in

water, ethanol, and methanol, and is nonfermentable.

When heated at 100



C for 1 h, solutions of stevioside

at pH 3–9 show little loss in sweetness and no change

at 22



C for 5 months. However, considerable decom-

position occurs at pH 10. Some degradation of stevio-

side and rebaudioside has been observed in

carbonated beverages acidified with phosphoric and

citric acids during storage at 37



C. Heating at 60



for 6 days has resulted in 0–6% loss of sweetness.

Exposure to 1 week of sunlight does not affect stevio-

side, but results in 20% loss of rebaudioside A. The

high stability of stevioside makes it a suitable sweet-

ener for cooked and baked foods and for beverages.

0028 Stevioside suppresses the growth of oral micro-

organisms, and both stevioside and rebaudioside A

provide very few calories. In Paraguay, S. rebaudiana

is used for the treatment of diabetes because of its

hypoglycemic activity. Studies have suggested that

stevioside is not toxic, mutagenic, or teratogenic in a

number of animal species. In addition, the product

has been used for more than 10 years in South

America and Japan, but there are contradictory

reports on the in-vivo metabolism to steviol, which

is mutagenic for Salmonella typhimurium TM677.

0029 Stevioside is available in three purity ranges: crude

extract, and 50% and 90% purity. Since 1970, stevia

sweeteners have been used in a wide range of food

and beverage applications in Japan, including soft

drinks, candies, chocolate, chewing gum, icecream,

yogurt, jam, pudding, and table-top sweeteners. It is

commonly used in combination with sucrose and

fructose and also with other sweeteners such as aspar-

tame, cyclamate, and acesulfame-K, but not with

saccharin. It is currently approved for use in Japan,

Taiwan, and Mercosur. An acceptable daily intake of

stevioside for humans of 7.94 mg per kilogram of

body weight has been suggested.

Thaumatin

0030 Thaumatin is a mixture of sweet proteins originally

isolated from the fruit of the West African plant

katemfe (Thaumatococcus danielli Benth.). There

are at least five thaumatins, which are obtained by

extraction with water, concentration, and ultrafiltra-

tion. Tate and Lyle Ltd. manufactures a mixture of

two as talin. These are proteins with isoeletric points

of 11.5–12.5. Thaumatin consists of a single chain of

207 normal amino acid residues with eight disulfide

bonds and has a molecular weight of about 22 000. It

is very soluble in water (600 g l

1

) and is stable at pH

2.7–6.0 and under pasteurization conditions (Table

1). At higher pH values, the protein becomes more

heat-labile, despite its stability at pH values up to 8

under ambient conditions. The stability of solubilized

thaumatin requires careful monitoring of pH, time,

temperature, and other processing parameters. In

addition, protection of the protein against yeasts

and molds in solutions is also critical for stability.

Thaumatin can associate with negatively charged

compounds such as synthetic colors and acidic gums

like xanthan, pectin, carrageenan, alginate, and car-

boxymethylcellulose, resulting in a loss of sweetness.

Association with synthetic colorants may also cause

color loss.

0031Thaumatin is 1600–3000 times sweeter than su-

crose. However, it has unusual taste profile, slow in

onset, followed by intensification to lingering sweet-

ness with a licorice-type aftertaste. It masks metallic

or bitter tastes. To achieve a taste closer to that of

sucrose, thaumatin must be blended with other in-

tense sweeteners or with sugars. Synergism has been

observed with saccharin, acesulfame-K, and stevio-

side, but not with aspartame and cyclamate. By com-

bining thaumatin with alanine and organic acids,

there is a doubling in sweetness and a reduction in

aftertaste and in the delay in sweetness. At subsweet-

ness levels, thaumatin functions as a flavor enhances.

It has the ability to enhance certain flavors and

aromas, such as those in peppermint, spearmint,

coffee, and ginger. The synergistic effect noted with

monosodium glutamate enhances the aroma and im-

proves the flavors of processed meats and fish prod-

ucts when used at levels of 0.5–2.0 g l

1

0032Thaumatin can be metabolized to its constituent

amino acids, contributing the same calories as pro-

tein. However, because of its high sweetness, it has a

low-calorie value per unit of sweetness, less than

0.002 kcal. It is noncariogenic and has undergone

safety tests indicating that it is not allergenic, muta-

genic, or teratogenic. Furthermore, it has a long his-

tory of use without any adverse effects. In 1985, a

‘not specified’ ADI was allocated by the JECFA. It has

been approved for use in Japan, the UK, Australia,

Canada, South Africa, Mexico, the European Union,

Switzerland, Taiwan, Morocco, and Tunisia. In

the USA and Switzerland, it is permitted as a flavor

enhancer in chewing gum, and in the USA, it has been

classified as GRAS.

SWEETENERS/Others 5701

0033 The major uses include chewing gum, beverages,

coffee, savory flavor, dairy products, dental and

pharmaceuticals, animal and pet foods. However, be-

cause of its high cost, it is used on a small scale.

Biotechnological alternatives to eliminate uncertain-

ties and variability associated with agricultural pro-

duction and to lower costs are being investigated.

Blends of Sweeteners

0034 Today, there is an increasing tendency to explore

the use of blends of sweeteners. When two or more

sweeteners are combined, blends with an increased

stability, longer shelf-life, lowered production costs,

improved taste and flavor, and decreased side- and

aftertastes result, as well as a positive impact on taste

quality, flavor-enhancing, and flavor-modifying prop-

erties. Also, mixtures of sweeteners can exhibit addi-

tive and synergistic effects, and since lower amounts

of each sweetener can be used, the average daily

intake of each sweetener is low, thus minimizing the

health risk from any one sweetener.

0035 Since food laws in most countries regulate the use

of intense sweeteners, analytical control for the pres-

ence and levels of sweeteners in food is essential.

According to the JECFA, it is also important to

know the level of additives in food products in order

to estimate the actual consumption by the popula-

tion. This information shows the average intake in

relation to the ADI over a period of time. Based on

this knowledge, regulatory authorities can propose

regulations to insure intakes below the ADI. Further-

more, some sweeteners undergo decomposition

during processing and storage of food products,

forming a variety of degradation products that may

have sensory and toxicological significance.

0036 Several types of methods have been described for

the analysis of intense sweeteners, among them, spec-

trophotometric, enzymatic, titrimetric, capillary iso-

tachophoretic, thin-layer chromatography, liquid and

gas chromatographic methods. High-performance

liquid chromatography (HPLC) is by far the most

frequently used technique. However, with the in-

creased number of sweeteners available and their

use being approved in specified food products and

beverages by different countries, methods capable of

separating several sweeteners simultaneously are still

required.

Further Reading

Borrego F, Canales I and Lindley MG (1995) Neohesperidin

dihydrochalcone: state of knowledge review. Zeitschrift

r Lehensmitte/untersuchung und -forschung 200:

32–37.

Duffy VB and Anderson GH (1998) Position of the Ameri-

can Dietetic Association: use of nutritive and nonnutri-

tive sweeteners. Journal of the American Dietetic

Association 98(5): 580–587.

Dwivedi BK (1993) Artificially sweetened low-calorie foods

other than drinks. In: Altschul AM (ed.) Low-calorie

Foods Handbook, pp. 331–342. New York: Marcel

Dekker.

Fenwick GR, Lutomski J and Nieman C (1995) Liquorice,

Glycyrrhiza glabra L. – composition, uses and analysis.

Food Chemistry 38(2): 119–143.

Giese JH (1993) Alternative sweeteners and bulking agents:

an overview of their properties, function and regulatory

status. Food Technology 47(1): 114–126.

Glo

ria MBA (2000) Intense sweeteners and synthetic color-

ants. In: Nollet LML (ed.) Food Analysis by HPLC,

pp. 523–573. New York: Marcel Dekker.

Grenby TH (1991) Intense sweeteners for the food industry:

an overview. Trends in Food Science and Technology

2(1): 2–6.

Hollingsworth P (1998) Sucralose approval sweetens low-

cal market. Food Technology 52(5): 34.

Hough L (1993) High-intensity, low calorie sweeteners. In:

Khan R (ed.) Low Calorie Foods and Food Ingredients,

pp. 138–164. New York: Blackie.

Liu J, Ong CP and Li SFY (1997) Subcritical fluid extrac-

tion of stevia sweeteners from Stevia rebaudiana. Jour-

nal of Chromatographic Science 35(9): 446–450.

Renwick AG (1990) Acceptable daily intake and the

regulation of intense sweeteners. Food Additives and

Contaminants 7(4): 463–475.

Sardesai VM and Waldshan TH (1991) Natural and

synthetic intense sweeteners. Journal of Nutritional

Biochemistry 2(5): 236–244.

Schaller I (1997) Is Codex the answer? Food Ingredients

Analysis International 19(3): 24–28.

Staff Report (1996) Thaumatin – the sweetest substance

known to man has a wide range of food applications.

Food Technology 50(1): 74–75.

Verdi RJ and Hood LL (1993) Advantages of alternative

sweeteners blends. Food Technology 47(6): 94–101.

Wallis KJ (1993) Sucralose: features and benefits. Food

Australia 45(12): 578–580.

5702 SWEETENERS/Others

SWEETS AND CANDIES

Sugar Confectionery

W P Edwards, Bardfield Consultants, Gt. Bardfield, UK

Background

0001 The confectionery industry is not a science-based

industry: it is an industry that has been built on

the confectioner’s craft. Confectionery is normally

divided into three classes: flour confectionery, choc-

olate confectionery, and sugar confectionery. Flour

confectionery covers products that are made from

flour and are baked. Chocolate confectionery consists

of chocolate. Sugar confectionery covers the rest of

confectionery.

0002 Confectionery making does share some technolo-

gies with the pharmaceutical industry, specifically

tabletting, panning, and lozenge making. Most of

the knowledge available to early confectioners was

empirical rather than scientific.

0003 Sugar confectionery making is an international

industry. Some of the terms in use are clearly French

in origin such as fondant (from fondre to dissolve),

dragees, and pastilles. Unlike chocolate confection-

ery, sugar confectionery has few legal definitions.

In some jurisdictions, caramel has a higher milk

content than toffee, but in others, the two terms are

used interchangeably. The types of product known

as gums were undoubtedly originally made from

the gum from Acacia senegal but are now made

from any suitable ingredient. Because sugar confec-

tionery has a long shelf-life and does not need con-

trolled temperature storage, an international trade

in confectionery had developed by the nineteenth

century.

0004 In general, the important concepts in sugar confec-

tionery are water activity, colligative properties, solu-

bility, and the need to use a mixture of sugars. Toffees

depend on the Maillard reaction. High boilings re-

quire a sugar glass to form. Gums, jellies, and licorice

need the right rheology. Panned coatings depend on

crystallization. Chewing gum is a chewable piece of

polymer chemistry. Aerated products are based on

stabilizing and setting a foam.

Stability

0005 Sugar confectionery products keep well compared

with most food products. The long life of confection-

ery products occurs because spoilage organisms are

unable to multiply rather than because the product is

kept sterile.

Water Activity

0006The relevant parameter is not only the water content

but the water activity. Water activity is a thermo-

dynamic concept that was invented to explain why

materials with different levels of water content did

not behave in the same way chemically or biologic-

ally. The water activity reflects the ability of the water

to be used in chemical or biological reactions. It is the

concentration corrected for the differences in the abil-

ity of the water to undertake chemical reactions. If a

nonvolatile solute were dissolved in water, the vapor

pressure should decrease in a certain way for a perfect

mixture. A thermodynamically ideal substance would

always have a water activity of 1. If a product is held

at its own water activity, it will neither gain nor lose

weight.

Equilibrium Relative Humidity (ERH)

0007This term is normally abbreviated to ERH. The

ERH is the relative humidity that matches the water

activity of the product. The ERH has practical im-

portance, since it is an indication of the conditions

under which the product can be stored without de-

terioration.

Colligative Properties

Boiling Points

0008Colligative properties are defined as those properties

that depend on the number of particles present rather

than the nature of the particles. In sugar confection-

ery, the most important of these is the elevation of the

boiling point. Because sugars are very soluble, very

large boiling point elevations are produced, e.g., as

large as 50



C. Remembering that the elevation of the

boiling point is proportional to the concentration of

the solute, it is not surprising that the boiling point is

used as a measure of the concentration and hence as a

process control.

0009The boiling point of a liquid is the temperature at

which the vapor pressure is equal to the atmospheric

pressure. If the pressure is increased, the boiling point

will increase, whereas reducing the pressure will

reduce the boiling point. Most sugar confectionery

is made by boiling a mixture of sugars to concentrate

them. The use of a vacuum has several advantages.

SWEETS AND CANDIES/Sugar Confectionery 5703

The energy consumption is reduced, browning is

reduced, and the process is speeded up. A common

practice is to boil a mixture of sugars under atmos-

pheric pressure to a given boiling point. A vacuum is

then applied. This causes the mixture to boil under

reduced pressure. This not only concentrates the

mixture while the latent heat of evaporation cools it

rapidly but also speeds up the production process,

since the product will ultimately have to be cooled

to ambient temperature.

Solubility

0010 Sucrose is insufficiently soluble, at ambient tempera-

tures, to lower the water activity sufficiently to give a

microbiologically stable solution. A stable product

can only be made by mixing the sucrose with other

sugars. The ingredient that is most used as a source of

nonsucrose sugars is the starch hydrolysate known

variously as glucose syrup or corn syrup. Neither

name is entirely accurate as the major ingredient is

normally maltose rather than dextrose, but the

product can be, and is, manufactured from wheat or

potato starch as an alternative to maize starch. The

degree of hydrolysis is characterized by the dextrose

equivalent (DE), which is a measure of the equiva-

lence of the solids in the syrup to dextrose in the

Fehlings titration. The type of syrup normally used

is referred to as confectioners’ glucose and has a DE

of around 40.

0011 In this work to avoid confusion between glucose

syrup and chemical dextrose, glucose will only be

used to refer to the syrup, and the pure sugar will be

referred to as dextrose.

0012 Originally, the starch was hydrolyzed by using

acid, which is a random process. Now, hydrolysis

can be carried out by enzymes or a mixture of

enzymes and acid. Using enzymes, it is possible

to control which bonds are broken to allow the com-

position of the product to be varied as needed. In

principle, the starch could be hydrolyzed to produce

any combination of dextrose oligomers from dex-

trose through maltose and maltotriose to higher

oligomers.

0013 The proportion of glucose syrup used in different

types of sugar confectionery varies for a number of

reasons. Commercial pressure would encourage the

use of a maximum amount of glucose syrup solids,

but technical considerations restrict the proportion

to be used. As glucose syrup inhibits crystallization,

the highest proportion is used where crystallization

is undesirable, e.g., in boiled sweets, and the lowest

where crystallization is desirable, e.g., fondant.

Figure 1 shows the ratio of sugar to glucose used for

different products.

Maillard Reaction

0014A major feature of sugar confectionery manufacture

is ensuring that the Maillard reactions occur where

they are wanted in products like toffees and do not

occur in products like high boilings.

0015Maillard reactions are nonenzymic browning reac-

tions. In practice, any browning in foods is a Maillard

reaction except where it is enzymic, e.g., the

browning of a cut apple is enzymic; hence, it is not

a Maillard reaction. The Maillard reaction is not a

name reaction where all the details can be found in a

text book. The term covers a whole range of reactions

that occur in systems ranging from food to life

sciences. The name of the reaction goes back to

Louis Camille Maillard, who heated amino acids in

a solution with high levels of dextrose. The chemistry

of the Maillard reaction is easily described as com-

plex. It is complex not only because the reaction can

give complex products but because the starting ma-

terials are themselves complex. Most model systems

involve studies of one reducing sugar being heated

1S:3G 1S:2G 1S:1G 2S:1G 3S:1G 4S:1G 5S:1G

Ratio of sugar to glucose syrup solids

Saturated solution

Syrup solids too low

Gums

and

pastilles

Jellies and mallows

Fondant

pastes

Toffees

fudge

Grained

Ungrained

Boilings Edinburgh rock (graining)

% soluble solids

Nougat

fig0001Figure 1 Sugar and glucose composition of confectionery.

5704 SWEETS AND CANDIES/Sugar Confectionery

with one amino acid. A typical confectionery system

like a toffee would involve heating a mixture of

proteins, usually from milk with a mixture of redu-

cing sugars and fats. In sugar confectionery, the con-

ditions of the reaction are likely to be a high

temperature but a low water activity. In the early

stages of the reaction, the free amino group of an

amino acid, usually in a protein, condenses with the

carbonyl group of a reducing sugar. The resulting

Schiff bases can rearrange by Amadori (Figure 2)or

Heyns rearrangement (Figure 3), the products being

an N-substituted glycosylamine (if dextrose is the

sugar) or an N-substituted fructosylamine for a

ketose such as fructose. The N-glycosylamine can

degrade to fission products by a free-radical mechan-

ism. In the advanced stages of the reaction, the Ama-

dori and Heyns rearrangement products degrade by

one of three possible routes. They break down via

deoxysones, fission, or Strecker degradation (Figures

4 and 5). The 1-deoxyglycosones and 3-deoxyglyco-

sones can form reactive a-dicarbonyl compounds

such as pyruvaldehyde and diacetyl by a retro-aldiza-

tion reaction. These reactive intermediates are then

available to react with ammonia and hydrogen

sulfide.

0016 At the end of the reaction, brown nitrogen-

ous polymers and copolymers form. It is known

that protein gels form when proteins are heated

with carbonyl compounds. This could occur in

toffees.

Sulfur-containing Amino Acids

0017Whereas sulfur free amino acids are broken down to

amines via decarboxylation, the sulfur containing

amino acids such as cysteine can undergo more

complex reactions.

Products from Proline

0018Various schemes have been proposed to explain the

production of nitrogen-containing heterocyclic com-

pounds such as pyrrolidines and piperidines from

proline. Nitrogen heterocyclic compounds are com-

monly found to be potent flavoring chemicals.

Strecker Aldehydes

0019These chemicals are produced by the Strecker degrad-

ation of the initial Schiff base (Figure 5). An a-amino

carbonyl compound and Strecker aldehyde are

generated by rearrangement, decarboxylation, and

hydrolysis.

Sugar Glasses: The Chemistry of Boiled

Sweets

0020In these products, which are variously called high

boilings, hard boilings, hard candy, or boiled sweets,

the sucrose is in the glassy state. The glassy state

of matter is not a thermodynamic phase but a

super-cooled liquid. Glassy materials are common in

a number of products, whereas both natural and

CHOH

NHR

CHOH

NRH

CHOH

COH

NRH

CHOH

1-Amino-2-keto sugarEnolSchiff baseN-Glycosylamine

(if aldose is

lucose)

Aldose sugar

fig0002 Figure 2 Amadori rearrangement.

CHOH

Ketose sugar

COH

CHOH

O H

N-Fructosylamine

(if ketose is fructose)

CHOH

2-Amino-1-keto sugar

CHOH

Enol

fig0003 Figure 3 Heyns rearrangement.

SWEETS AND CANDIES/Sugar Confectionery 5705

man-made substances can form glasses. Confusingly,

although a glass is not a thermodynamic state of

matter, glasses do exhibit a sharp transition tempera-

ture between the glassy and the rubbery state. Many

methods have been used to determine the transition

temperature between the rubbery and the glassy state.

One popular method is differential scanning calorim-

etry (DSC). In these instruments, the sample and a

blank are subjected to a change of temperature up or

down at a controlled rate. The instrument measures

the difference energy input or energy extracted be-

tween the sample and the control. A plot of differ-

ence gives the variation of heat capacity, C

, with

temperature. The glass transition is associated with

a discontinuity in C

. Unfortunately, there are a

number of different ways in which the output from

the DSC can be analyzed. Some workers would advo-

cate integrating the result from the DSC, i.e., measur-

ing the area under the curve. This then gives the

variation of the enthalpy with temperature. The vari-

ation in several other physical parameters with tem-

perature such as the refractive index and the dielectric

constant have been used to measure glass transitions.

In general, the glass transition temperature obtained

depends on the method of measurement. In confec-

tionery, the important point is that a product that is

intended not to crystallize should be in the glassy state

at ambient temperatures. Most sugars will form a

CHOH

2-Amino-1-keto sugar

Heyns intermediate

1-Amino-2-keto sugar

Amadon intermediate

Enolization

−H

−RNH

−H

COH

CHOH

3-Deoxyosone

COH

CHOH

1,2-

Enolisation

2.3

CHOH

Enolization

1-Methyl-

2,3-dicarbonyl

fig0004 Figure 4 Formation of furans and dicarbonyls.

5706 SWEETS AND CANDIES/Sugar Confectionery