Caballero B. (ed.) Encyclopaedia of Food Science, Food Technology and Nutrition. Ten-Volume Set

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Physical Properties

0009 Crystalline sucrose Sucrose in a pure state crystal-

lizes in a monoclinic system, forming transparent,

colorless, and odorless sphenoidal prismatic crystals,

the form of which may be strongly affected by impur-

ities (needle-like shapes).

0010 Sucrose has a characteristic sweet taste without any

other flavor or aftertaste; it is the standard reference

for sweetness. If sucrose is given a sweetness rating of

100, the relative sweetness of fructose is between 105

and 125 and that of glucose between 65 and 75,

depending on the conditions (acidity, pH, tempera-

ture, etc.).

0011 The crystal density (D

) is 1.5879, but the appar-

ent specific gravity of high-grade white sugar varies

between 0.72 and 0.88 kg dm

3

, depending on the

crystal size and humidity, the storage duration, and

the thickness of the layer in the storage silo.

0012 Sucrose decomposes at about 186–188



Cto

form brown products (caramel) and, finally, chars,

but impurities and the products of thermal decom-

position significantly lower the temperature of de-

composition.

0013 The heat of combustion is 1351.3 kcal mol

1

3.95 kcal g

1

. Sucrose is thus less caloric than fat

(9.3 kcal g

1

) and protein (4.1 kcal g

1

0014 Sucrose solutions Sucrose is readily soluble in water,

and its solubility increases with temperature. By

cooling or evaporating a saturated sucrose solution,

a metastable supersaturated solution is obtained.

Sucrose is sparingly soluble in ethanol and practically

insoluble in ether.

0015 The solubility of sucrose has been calculated at

different temperatures. In 1978, the International

Commission for Uniform Methods of Sugar Analysis

(ICUMSA) officially adopted the tables of Vavrinecz

and of Charles. Table 1 gives example solubilities at

various temperatures, which have been taken from

the Charles tables.

0016Sucrose in aqueous solution has the property of

rotating the plane of linear polarized light, and the

angle of rotation is proportional to the concentration

and to the path length of the solution traversed by

the light beam. This angle is measured by means of

polarimeters. In the sugar industry, special polarim-

eters, called ‘saccharimeters,’ are directly calibrated

in ‘degrees sugar’ (



Z). The ICUMSA adopted a

new definition of the international sugar scale as

from 1 July 1988. The basis of the 100



Z point of

the international sugar scale is the optical rotation

of a ‘normal sugar solution’ at the wavelength (l)

of the green line of the mercury isotope

198

(l ¼546.2271 nm in vacuo) measured at 20.000



in a 200.000-mm polarimeter tube. The ‘normal

sugar solution’ corresponds to a concentration of

26.000 g sucrose weighed with brass weights in air

under normal conditions (1013 hPa pressure, 20



50% relative humidity) in 100.000 cm

of solution at



C. On this new international sugar scale, the op-

tical rotation of the 100



Z point is 40.777 + 0.001



0017The density of sucrose solutions is a function of the

mass concentration and of the temperature. The dens-

ity values universally used are those of Plato (first

published in 1900) giving D

for the solutions

tbl0001Table 1 Solubility of sucrose at four example temperatures

according to the ICUMSA



C) Solubility of sucrose (g) in

1g of water 100 g of solution

10 1.884 65.32

20 1.994 66.60

50 2.576 72.04

90 4.262 81.00

HCOH

HOCH

HCOH

HOCH

(a) (b)

HOCH

fig0001 Figure 1 Structural representations of sucrose: (a) Fisher projection; (b) Haworth-type structure. Reproduced from Sucrose:

Properties and Determination, Encyclopaedia of Food Science, Food Technology and Nutrition, Macrae R, Robinson RK and Sadler MJ

(eds), 1993, Academic Press.

SUCROSE/Properties and Determination 5637

between 0 and 95 degrees Brix (grams per 100 g of

solution).

0018 The refractive index of sucrose solutions is a func-

tion of the amount of dissolved material and also of

the temperature. The ICUMSA has published refract-

ive index tables for sucrose solutions from 0 to 85

degrees Brix at 20 and 27



C, as well as temperature

correction tables.

0019 There are many other properties that have been

measured, such as viscosity, osmotic pressure, specific

heat, boiling point elevation, and equilibrium relative

humidity, the knowledge of which is very useful in

food technology.

Structural Properties

0020 In addition to its use in food processing as a sweetener

and an energy source, sucrose has other functions.

Thus, it is not sufficient to replace sucrose by artificial

noncaloric sweeteners and expect simply to obtain

similar products with the same sweetness but without

the calories. (See Sweeteners: Intensive.)

0021 Sucrose acts as a preservative by its ability to

reduce water activity and to increase osmotic pressure

to a level where the growth of even the most osmo-

philic microorganisms is no longer possible (as in

jams, jellies, fruit syrups, concentrated milk).

0022 Sucrose acts as a bulking agent and a texturizer in

confectionery, baked goods, and soft drinks. Owing to

its high solubility and viscosity, it gives body and

mouth-feel to various preparations. It influences the

pore size distribution, softness, and structure of pastry.

0023 Sucrose also has properties of humectancy, i.e., it

assists the ability of products to withstand changes

in moisture content, and so extends the shelf-life of

goods such as cakes.

0024 Sucrose is an antioxidant, preventing the oxidation

of flavors in fruit preserves. (See Antioxidants: Nat-

ural Antioxidants.)

0025 Sucrose can fulfill the role of a diluent or carrier for

flavoring or coloring additives and, at the same time,

act as enhancer for natural food flavors, balancing

sweetness, sourness, and bitterness. Sucrose alone can

also give a caramel flavor and a browning of the

products in baking, as a result of partial degradation.

Inversion on Storage and Processing

0026 Sucrose, in a solid crystallized form, is one of the most

chemically pure food products available in the world

with a purity of 99.97 + 0.05%. It can be stored

unchanged almost indefinitely under ideal conditions.

To avoid caking or, conversely, attraction of moisture

or even liquefaction in the silo, the sugar produced,

prior to storage, must be dry and cold and must have

undergone a conditioning process.

0027Freshly produced crystals are surrounded by a thin

film of supersaturated mother liquor and possibly

contain syrup inclusions. It takes a few days to

achieve crystallization and to release free moisture,

and, if this water is not allowed to escape, serious

storage problems can occur, such as chemical or

microbiological inversion, and, with the lowering of

the pH, an accelerated degradation with formation

of colored products. It is thus useful to store sugar

initially in a holding bin aerated with cold dry air

before storage in the final silo.

Fermentation of Sucrose

0028Sucrose may be readily fermented by several micro-

organisms and is a good starting material for the

microbial production of many chemical products

such as ethanol, butanol, glycerol, citric acid, levuli-

nic acid, dextran, and many others. Molasses, a

byproduct of the sugar industry that no longer con-

tains crystallizable sucrose, is often used as a cheap

source for these processes.

0029The most important fermentation process known

from time immemorial is probably alcoholic fermen-

tation by yeasts used to produce beverages such as

beer and wine. The first stage of alcoholic fermenta-

tion is an enzymatic hydrolysis of sucrose to glucose

and fructose by invertase.

Analysis, Extraction, and Isolation

0030The term ‘sucrose analysis’ can include numerous

determinations depending on the purpose of the

analysis.

Sucrose in the Solid State (Commercial Sugars)

0031The purity of sucrose can be determined by polarim-

etry or, indirectly, by determining the amount of non-

sucrose material present, i.e., water content and other

compounds (organic or inorganic).

0032The water content can be determined by direct

methods, such as the Karl–Fischer titration or the

conventional ‘loss on drying’ method.

0033Inorganic compounds can be evaluated gravimetri-

cally by incineration of the sugar. The result is the

sum of the water-soluble and water-insoluble residues

or ‘ash’ in the form of ‘carbonate ash’ or ‘sulfated

ash,’ according to the method chosen. Ionized soluble

salts (‘conductivity ash’) can be determined con-

ductimetrically. This method is easier and less time-

consuming than incineration, but does not have

precisely the same significance as ‘gravimetric ash.’

0034Among the so-called organic nonsugars, there

may be small amounts of ‘invert sugar,’ a mixture of

reducing sugars. There are numerous methods to

5638 SUCROSE/Properties and Determination

determine reducing sugars in the presence of sucrose,

based on the reduction of a copper(ii) complex with

tartaric acid in alkaline solutions, e.g., Lane and

Eynon titration, in addition to the Emmerich method

for the determination of traces of reducing sugars in

pure sucrose.

0035 It is also possible, when required, to determine

individual ions such as copper, lead, iron, calcium,

chloride, arsenic, sulfite, and organic nonsugars such

as aminonitrogen, betaine, lactic acid, citric acid, and

so on.

0036 In addition to the above purity evaluations, buyers

require other quality criteria according to the specific

uses intended for the sucrose. These may include

particle size and uniformity, visual appearance,

color and turbidity in aqueous solution or in alcoholic

solution, insoluble matter or the presence of visible

extraneous impurities, filterability, foaming pro-

perties, and floc formation in soft drinks. Some

industries have special requirements concerning

microbiological quality. For instance, the canning in-

dustry has a procedure for determining spore-forming

thermophilic bacteria, and in the soft drinks industry,

procedures are carried out for the detection of meso-

philic bacteria, yeasts, and molds.

Sucrose Solutions and Technical Sugar Juices

0037 Polarimetry may be used to determine the sucrose

content of pure sucrose solutions and of intermediate

liquid sugar products. In the latter case, it will often

be necessary to eliminate many impurities to obtain a

clear solution to allow passage of light through the

polarimeter tube. This clarification is normally

achieved with basic lead acetate solution, but the

present trend is to replace this toxic reagent with

nontoxic clarifying agents such as aluminum salts.

0038 It is also possible to measure the densities or

refractive indices of pure sucrose solutions to deter-

mine the sucrose content, since these values are func-

tions of the sucrose concentration. For impure sugar

juices, the influence of the soluble nonsucrose com-

pounds on these parameters is almost the same as that

of the sucrose. Consequently, the measurement repre-

sents the total soluble dry matter of the solution and

allows the determination of the degree Brix (or degree

Balling), i.e., the percentage of dry matter in the

solution. The ratio of sucrose content (Pol) to total

soluble dry matter (Brix) is called the quotient of

purity (Q):

Q ¼

Pol

Brix

 100 ð2Þ

The density can be measured by pycnometers

or hydrometers, possibly calibrated in degrees

Brix (formerly in degrees Baume

). However, these

densitometric methods require many precautions

and are time-consuming. It is much easier to measure

the refractive index, but because the influence of the

nonsugars is not the same, a distinction must be made

between densitometric Brix and refractometric Brix,

giving a slightly different purity quotient. (See Rheo-

logical Properties of Food Materials.)

Sugar-containing Products (Sweet Foods,

Molassed Feeds)

0039Considering the high solubility of sucrose in water,

the first step in analysis will often be an aqueous

extraction followed possibly by clarification (or

sometimes an aqueous alcoholic extraction). As glu-

cose or invert sugar will also be frequently present

in this extract, a double polarization or a double

reducing sugars determination should be made, one

before and one after inversion of the sucrose present

in the extract. By calculation, the total sugars and

sucrose content of the product can be determined.

0040In the sugar industry, the sugar content of beet or

cane has to be determined, as this is the basis of

payment for the raw material and allows calculation

of the amount of sugar entering the factory. For this

purpose, there are conventional methods specific to

the sugar industry.

Traces of Sugars

0041It can be important to detect traces of sugar in some

products, such as the presence of sugar in the feed

water of boilers as a result of the use of condensed

water from the sugar juice evaporation, and to

control the losses of sugar in the waste water. This is

carried out by qualitative or semiquantitative

methods (a-naphthol with sulfuric acid) or by auto-

matic apparatus based on chemical reactions or phys-

ical properties (conductivity or fluorescence).

Methods of Analysis

0042Polarization This method is based on measurement

of the rotation of polarized light of a solution con-

taining the normal weight (i.e., 26 g in 100 cm

)ofa

sugar sample or of the unknown sugar solution to be

examined (after clarification if necessary) by means of

a saccharimeter calibrated to give 100



Z with pure

sucrose. Calibration of the saccharimeter is carried

out with standard quartz plates. The result is given as

the percentage of sucrose in the sugar sample or of the

unknown sugar solution to be analyzed.

0043Loss on drying Instead of speaking of water content

in this indirect method, it is more correct to speak of

‘loss on drying.’ The principle of this method is the

determination of the loss in weight of a sugar sample

placed in an oven at 105



C for 3 h and cooled

SUCROSE/Properties and Determination 5639

afterwards in a desiccator under uniform conditions.

The loss in weight for a high-grade white sugar is

normally between 0.02 and 0.05%.

0044 Conductivity ash The specific conductivity of a so-

lution containing 28 g of sugar per 100 g is measured

at 20



C. The water used will have a conductivity of

less than 2 mScm

1

. The concentration of 28 degrees

Brix has been chosen because the conductivity curve

shows a flattened peak in this concentration region.

The measured conductivity corrected for the water

used is converted by a conventional factor into the

percentage of conductivity ash in the sugar.

0045 Visual appearance The visual grade of crystalline

white sugar is assessed by comparing the sample

with standard color types numbered from 0 to 6,

made up of sugar artificially colored and of a defined

particle size. The comparison is made by eye under

well-defined conditions. Some instruments are now

on the market that are intended to replace the eye

and so yield a better reproducibility. (See Sensory

Evaluation: Appearance.)

0046 Color and turbidity in solution A solution of 50 g of

sugar in 50 g of a buffer solution at pH 7 is filtered

through a 0.45-mm membrane filter, and the absor-

bancy of the deaerated filtered solution is measured

by means of a spectrophotometer at a wavelength of

420 nm. The final result is expressed in ICUMSA

color units as a percentage of the dry sample.

0047 Turbidity is measured by means of a turbidimeter

calibrated with a formazin turbidity standard. The

result is expressed in nephelometric turbidity units.

0048 Floc test The soft-drink industry uses various tests

to check the appearance of a floc during the shelf-life

of a bottled beverage. This floc formation, in acid

conditions, may be due to the presence of polysac-

charides (gums).

0049 Sulfur dioxide The level of sulfur dioxide in sugar is

often limited by national legislation. A method of

determining low levels of sulfur dioxide in white

sugar is based on a colorimetric determination of

the sulfite/rosaniline complex, as measured by spec-

trophotometry at a wavelength of 560 nm after

reaction with formaldehyde.

0050 Particle size The particle size of crystalline sugar

can be characterized by the mean aperture (MA)

and coefficient of variation (CV). The MA is the

theoretical mesh aperture, in millimeters, of a sieve

that retains (and also lets through) 50% of the sugar.

The CV is the standard deviation expressed as a

percentage of the MA. It is an evaluation of the dis-

persion of the crystal size around the MA.

0051Chromatographic methods High-performance liq-

uid chromatography (HPLC) and gas–liquid chroma-

tography (GLC) techniques for the analysis of

commercial sugar products have been developed in

recentyears.(SeeChromatography:High-performance

Liquid Chromatography; Gas Chromatography.)

0052Sucrose in beet and cane molasses can be deter-

mined by GLC. Molasses samples together with tre-

halose as an internal standard are silylated using a

trimethylsilyl (TMS) reagent to convert the sugars

into a form in which they are volatile. The TMS

ethers of sucrose and trehalose are separated from

each other and from other volatile components

using a low- to medium-polarity column. Detection

is carried out using a flame ionization detector, and

accurate estimation of the sucrose content can be

achieved by measurement of the peak areas with the

use of an electronic integration system. Sucrose, glu-

cose, and fructose in cane molasses can be determined

by GLC according to the method described above by

introducing an oxime formation step prior to the

silylation.

0053Sucrose in beet and cane molasses can also be

determined by HPLC. The separation column is a

cation-exchange resin converted to a metal ion

form. The diluted sample is filtered prior to injection

on the column. The hydroxyl groups of the different

sugars interact with the cations to varying extents,

resulting in different elution times. Detection is

achieved by differential refractometry of the column

eluant. The peak area or height for sucrose is

obtained by an electronic integration system, which

is compared to that obtained for standards.

White Sugar or Refined Sugar

0054Irrespective of whether a sugar is a product of the

‘first strike’ or has actually been refined by remelt,

decoloration, and recrystallization, the EC has de-

fined a number of criteria to which a sugar must

correspond, to be called ‘white sugar’ or ‘refined

sugar.’ The criteria are based on the results of some

of the analyses described above – polarization, loss on

drying, conductivity ash, visual appearance, color in

solution, invert sugar, and sulfur dioxide content.

See also: Antioxidants: Natural Antioxidants;

Carbohydrates: Classification and Properties;

Chromatography: High-performance Liquid

Chromatography; Gas Chromatography; Date Palms;

Fructose; Rheological Properties of Food Materials;

Sensory Evaluation: Appearance; Sorghum; Sugar:

Sugarcane; Sweeteners: Intensive

5640 SUCROSE/Properties and Determination

Further Reading

Birch GG and Parker KJ (1982) Nutritive Sweeteners.

London: Applied Science.

Clarke MA and Godschall MA (1988) Chemistry and pro-

cessing of sugarbeet and sugarcane. In: Sugar Series, vol.

9. Amsterdam: Elsevier.

International Commission for Uniform Methods of Sugar

Analysis (ICUMSA) (1978) Report of the Proceedings of

the 17th Session, Montreal.

International Commission for Uniform Methods of Sugar

Analysis (ICUMSA) (1982) Report of the Proceedings of

the 18th Session, Dublin.

International Commission for Uniform Methods of Sugar

Analysis (ICUMSA) (1986) Report of the Proceedings of

the 19th Session, Cannes.

International Commission for Uniform Methods of Sugar

Analysis (ICUMSA) (1990) Report of the Proceedings of

the 20th Session, Colorado Springs.

Mauch W (1971) The chemical properties of sucrose. Sugar

Technology Reviews 1(3): 239–290.

Mauch W and Farhoudi E (1980) Quality factors in com-

mercial white granulated sugar. Sugar Technology

Reviews 7(2): 87–171.

Norrish RS (1967) Selected Tables of Physical Properties of

Sugar Solutions. Scientific and Technical Surveys, No.

51. Leatherhead: The British Food Manufacturing In-

dustries Research Association.

Schneider F (1979) Sugar Analysis, ICUMSA Methods.

Peterborough: International Commission for Uniform

Methods of Sugar Analysis.

Dietary Importance

G H Anderson, University of Toronto, Toronto, Ontario,

Canada

Introduction

0001 For centuries, sucrose has played an important role

both in nutrition and in making foods palatable. Su-

crose, in many natural and refined forms, has been

widely used in the diet since its first recorded use in

India in 500 bc, when a rough sugar was produced

from boiled cane. This product was called gur, mean-

ing ‘nice, sweet, sticky stuff.’ Sugar began to be used

in the Middle East in 600–700 ad and reached wide-

spread usage in Europe by 1000 ad. From the eight-

eenth century onward, relatively inexpensive brown

sugar was available for the average family. The Indus-

trial Revolution and large-scale food processing

brought refined white sugar to everyone’s table, and

consumption increased rapidly. Since the mid-1920s

sugar consumption has remained relatively constant,

except during the Second World War, when rationing

led to a decrease in consumption.

0002Sucrose consumption has declined since the

1970s when nutritive sweeteners from corn became

available. Corn sweeteners are available as corn

syrups, other saccharides, or as high-fructose

corn syrup, which is produced by enzymatic conver-

sion of some of the dextrose to fructose. To avoid

confusion in this presentation, ‘sucrose’ will be used

when sugar from cane and beet sugar is being dis-

cussed and the word ‘sugars’ will be used when

all added free sugars, including corn sweeteners, are

discussed.

0003The facts about sugars today are often distorted,

producing incorrect public perceptions; therefore a

discussion of the metabolism, health implications,

and current consumption levels of dietary sugars

follows.

Digestion and Metabolism of Sucrose

0004Sucrose is hydrolyzed by the enzyme sucrase, an

a-glucosidase in the human small intestine, to its

component monosaccharides fructose and glucose.

About 10–25% of the fructose is converted to glucose

in the brush border of the upper gastrointestinal tract.

The monosaccharides are absorbed and transported

to the liver via the portal vein and subsequently trans-

ported to all tissues.

0005Within the liver fructose may be converted to glu-

cose; it may enter the glycolysis pathway, or provide

acetate units for the synthesis of fatty acids. Glucose

can be stored in the liver as the glucose polymer

glycogen; it can be used in glycolysis to produce

energy; or it can provide acetate units for the synthe-

sis of fatty acids.

0006Glucose is made available to other body tissues via

the blood stream and is the primary form of carbohy-

drate used as energy by the tissues. Under circum-

stances reflected by normal consumption of sucrose

or high-fructose corn syrups, little fructose appears in

the blood because it is rapidly metabolized by the

liver for synthesis of glucose and primarily fatty

acids and triglycerides, and possibly by metabolism

in the kidney. The utilization of fructose by peripheral

tissues seems to be negligible, perhaps because glu-

cose, which is always present in the blood, inhibits

both its uptake and entry into the metabolic pathway

of glycolysis.

0007As a result of insulin release in response to sucrose

ingestion, blood glucose is maintained within a

closely regulated range, a requirement for normal

functioning of the central nervous system. Sugar

does not cause abnormal insulin and blood glucose

responses. In fact, the effect of ingesting sucrose on

SUCROSE/Dietary Importance 5641

insulin release and blood glucose is less than when an

equivalent amount of carbohydrate is consumed from

bread. The excess of glucose above the energy re-

quirements of the tissues can be stored to some extent

as glycogen in muscle. The remainder is used to syn-

thesize fatty acids and glycerol, which allow efficient

storage of energy in the form of triglycerides in

adipose tissue.

0008 The effect of sugars on blood glucose can be cap-

tured by measuring the total glycemic response over

time. To compare the response produced by different

carbohydrates, the glycemic index (GI) was de-

veloped. The GI compares the incremental area

under the blood glucose curve produced by 50 g of a

carbohydrate test food to that produced by 50 g of

a standard food (white bread or glucose). The

glycemic indices of sugars depends on their compos-

ition. For example, sucrose has a GI which is only

87% of the white bread standard. This glycemic re-

sponse is explained by its components glucose and

fructose. Glucose alone has a GI relative to white

bread of 138%, whereas that of fructose is only

32%. Relative to many common starchy foods, both

sucrose and fructose have lower GI values (Table 1).

Nutritional Properties of Sucrose

0009 Sucrose has two important nutritional properties. It

provides energy at 3.8 kcal g

1

and, through its sweet

taste, it increases the palatability of foods.

0010Sucrose, in the form that it reaches the table of the

consumer, is the purest of common foods and free of

contaminating chemical residues. As a result, it pro-

vides only one nutrient, carbohydrate, which is read-

ily converted to energy by the body. It is this aspect of

sucrose that has led to the concept of ‘empty calories.’

Clearly, sucrose can be used to manufacture foods

that are low in essential nutrients and, if consumed

in excess, may lead to nutrient-deficiency syndrome.

However, there is no objective evidence that sugar

intake leads to nutrient deficiencies at current con-

sumption levels, nor that its widespread use has com-

promised the food supply so that nutritionally

adequate meals and diets cannot be obtained from

the marketplace.

0011Diets containing too much sugar are theoretically

possible, and examples based on readily available

foods can be easily constructed. For the majority of

people, however, consumption of sugar falls well

within a safe range of intake.

0012The probable reason why sugar does not lead to

nutrient-imbalanced diets is because it is used to en-

hance the intake of many nutrient-rich foods which

may not otherwise be readily eaten. For example,

small amounts of sugar are added to many fruits,

vegetables, and cereals. Increasing the palatability of

these foods with sugar makes them more likely to be

consumed.

0013Many reviews have examined the role of sugar in

health and indicate that, other than contributing to

dental caries, which is a consideration for all carbo-

hydrates, the amounts consumed in the average diet

produce no deleterious health effects. However, per-

ceptions that sugar is the cause of hypertriglycerid-

emia, diabetes, and hyperactivity in children still

persist.

0014Hypertriglyceridemia is the elevation of triglycer-

ides in the blood and is believed to play a role in heart

disease. It has been recognized for years that large

amounts of dietary sugars, particularly fructose, can

raise triglycerides. Thus, sugars that contain fructose,

such as sucrose and high-fructose corn syrups, also

have this potential. The potential effect of fructose

consumption on blood lipids is explained by its

unique metabolic pathway in the liver and evidence

that it is a better substrate than glucose for lipid

synthesis. Therefore, it should not be a surprise

to find an elevation of blood triglyceride con-

centrations in some subjects given excessive quan-

tities of fructose or sucrose. However in studies in

which amounts of sugars typical of the western diet

were provided, such responses are not usually

observed.

0015Diabetes mellitus is a condition in which an insulin

deficiency or decreased insulin sensitivity results in

tbl0001 Table 1 Glycemic index of selected foods

Foods Glycemicindex (GI)

White bread 100

All Bran 60

Cornflakes 119

Oat bran 78

Apple 52

Banana 83

Cornmeal 98

Rice, white 81

Rice, brown 79

Rice, instant 128

Rice, parboiled 68

Baked potato 121

Boiled white potato 80

Milk, whole 39

Spaghetti, white 59

Chocolate (various) 84

Sucrose 87

Fructose 32

Glucose 138

Soya beans 23

Selected from FAO/WHO (1997) Carbohydrates in Human Nutrition.

FAO/WHO Expert Consultation on Carbohydrates in Human Nutrition. Rome,

Italy: FAO/WHO.

5642 SUCROSE/Dietary Importance

hyperglycemia. The most prevalent form of diabetes

is noninsulin-dependent diabetes mellitus (NIDDM),

which most often has its onset in adulthood and is

associated with obesity. All reviews on the subject

have concluded that there is no evidence that sugar

intake is related to the incidence of diabetes or

mortality. In fact, as with obesity, an inverse relation-

ship between sugar intake and diabetes has been

found.

0016 The belief that sugar causes hyperactivity in chil-

dren is one of the most persistent and widespread

myths about sugar. However, the link between sugar

and hyperactivity has been based largely on subjective

observations made by both parents and teachers.

Recent well-controlled challenge studies clearly indi-

cate that sugar does not affect hyperactivity, attention

span, or cognition in children. In fact, studies have

shown that children are calmer and more sedate

following sugar preloads.

Sugar Consumption versus Sugar

Disappearance Data

0017 A great deal of confusion surrounds sugar consump-

tion statistics. This is because there are two types of

consumption being interchanged in discussion of the

statistics. One consumption statistic is based on

economic concepts and refers to national usage or

availability of sugar for use in the food supply,

whereas the other consumption statistic is an estimate

of the amount eaten by humans and is a physiological

concept.

0018 Estimates of the total amount of nutritive sweeten-

ers available for use within a country are assembled

on an annual basis by statistics or economic branches

of the government. The figures are reported as per

capita consumption, but they do not represent

per capita intake by individuals. They indicate avail-

ability of added sugars to the marketplace, after

consideration of production, imports, and exports,

and beginning and ending stocks. No allowance is

made for losses or wastage in food manufacturing or

in other aspects of usage. Thus, while these consump-

tion statistics have proved useful in describing trends

in national availability of added sugars, they have

proved to be misleading in predicting actual intake

by humans. For example, in 1980–85, total caloric

sweeteners available for consumption in the USA

averaged 155 g (620 kcal) per person per day and

17% of the energy content of the available food

supply. However, much of the sugar available is des-

troyed in production processes such as making bread,

pickles and alcoholic beverages, or wasted during

distribution, storage, and usage, or consumed by

animals.

0019Added sugar consumption in the USA was esti-

mated to average only 53 g day

1

, or 30% of

estimated availability (155 g) derived from disappear-

ance data in 1977–78. Consumption data for sugars

added to the food supply were derived from the

1977–78 (US Department of Agriculture (USDA))

Nationwide Food Consumption Survey. Average

daily intake of sugars for this population sample of

30 677 subjects was 53 g day

1

, or 11% of the daily

intake of calories. Younger age groups had a higher

intake than older age groups. The highest consumers,

those in the 90th percentile of daily intake of added

sugar, ranged from 1.5 to 2.5 times the mean value for

the 14 age/sex groups. For the total population the

90th percentile of daily intake of added sugar was

104 g day

1

or 20% of calories.

0020More recent (1999) economic estimates of per

capita consumption show that availability of caloric

sweeteners averages 196 g (745 kcal) per person per

day. This increase of 29%, since the early 1980s, is

somewhat less than the increased per capita availabil-

ity of total flour and cereal products (36%) and is

greater than the increase in total fat availability

(19%). When total added sugars availability is related

to the availability of calories in the food supply it now

approximates 20%, slightly up from 17% in the early

1980s. In contrast, more recent dietary surveys esti-

mate consumption of sweeteners to be close to 80 g

day

1

or nearly 18% of the energy consumed. These

data suggest that the amount of added sugars eaten

has risen by almost 50% from 20 years ago and is

42% of the added sugar availability. However the

majority of this reported increase in intake can be

accounted for by a change in the approach and defin-

ition of sugars used by USDA in reporting dietary

survey data.

0021By definition, sugars are mono- and dissaccharides

and this definition was used in the earlier survey

estimate of sugar intakes. In more recent surveys all

high-fructose corn syrups are included as added sugar,

which does not adjust for the 70% of these syrups

that are made up of polysaccharides. This fact, plus

the failure to consider loss of sugars in baking and

other processes, and the inclusion of high-intensity

sweeteners in the calculation, account for most of

the calculated increase in added sugar consumption.

Thus at present it is uncertain the extent to which the

modest increase in availability of added sugars as a

portion of the energy content of the available food

supply has influenced dietary intakes.

0022Since the mid-1970s there has been a consider-

able replacement of sucrose with corn sweeteners,

including high-fructose corn syrup, glucose syrups,

and dextrose. At the present time, corn sweet-

eners account for about 50% of the total added

SUCROSE/Dietary Importance 5643

sweetener that is available in the USA. Because the

most commonly used high-fructose corn syrups con-

tain 52% or less of fructose, their availability has

done little to affect fructose consumption compared

with the consumption of sucrose which is 50%

fructose.

0023 Due to changing lifestyles since the early 1900s, the

major use of sugars has shifted from direct use by

consumers in households to use by the food industry

in baked goods, processed foods, and beverages.

In 1925, consumer use accounted for about two-

thirds of total sugar disappearance, whereas the

food industry used only one-third. Today these figures

are reversed. In addition to the use of sugar as a

sweetener, it is widely used for its functional proper-

ties, such as providing bulk in baked goods and in-

hibiting spoilage microorganisms in jams and jellies.

These functional uses are the same whether they

occur in the home or the industry, and are essential

to achieving a safe and tasty food supply. Therefore

the shift to use by the food industry of a greater

proportion of sugar disappearance does not suggest

that the consumer is eating more sugar than in previ-

ous decades.

Dietary Goals and Guidelines

0024 Primarily because of concern with chronic disease,

developed countries have produced statements of

dietary goals and guidelines aimed at improving

the dietary pattern of their populations. The assump-

tion is that nutritional factors are important in the

development of chronic disease and that corrective

actions in terms of diet will prove to be beneficial.

0025 Sucrose has appeared prominently in dietary guide-

lines. Recent nutrition recommendations of the gov-

ernments of Canada and the USA have taken a more

liberal view of the nutritional role of sugar in the diet.

The American and Canadian Diabetes Associations

recommend that sugars and sugar-containing foods

do not need to be restricted by people with diabetes

and should be considered in the context of the total

amount of carbohydrates consumed. The Canadian

dietary guidelines for healthy people are silent on the

subject, based on the conclusion of the scientific

advisory committee that there was no basis on

which to advise reduction of sugar intake to the

population. Similarly, the guidelines for the USA

are no longer punitive and have shifted from ‘avoid

too much sugar’ to ‘choose beverages and foods

to moderate your intake of sugars.’ This advice

emphasizes the requirement of individuals to select

diets that are based on variety and moderation.

Avoidance of refined sugars is no guarantee of a

healthy diet.

Sucrose and Food Intake

0026Sucrose, through its sweetness and other functional

properties, makes foods more appealing and raises

the probability that they will be selected over foods

that are not as palatable. It is well known that the

hedonic value of a food is a major determinant of its

consumption. However, there is a natural response to

sweetness and palatability of foods that tends to be

self-limiting. Sensory-specific satiety, which refers to

the decreased pleasantness of a food or beverage as it

is consumed, occurs for all foods and tastes. Thus

increasing the pleasantness of a food may influence

its choice but does not necessarily lead to excess

consumption.

0027The role of a varied and palatable diet in the eti-

ology of obesity is currently of great interest because

of the high prevalence of obesity in western popula-

tions. In the past 40 years, the incidence of obesity has

increased fivefold. It is unlikely that sucrose can be

rationalized as a causative factor, for several reasons.

First, on a strictly correlative basis, the increase in

obesity does not associate with the constant intake of

sugars occurring during this same period. Second,

obese subjects do not show a disproportionate intake

of sweet foods compared with normal-weight indi-

viduals.

0028In contrast to hypotheses that sugars bypass appe-

tite-regulatory systems, experimental studies indicate

that consumption of sugars suppresses subsequent

energy intake. Both children and adults compensate

for energy provided by sucrose preloads when given

within 1 h before a test meal. Similarly, compensation

is also observed for other sugars, which produce

higher glycemic responses, including glucose and

polycose. Therefore, a rapid increase in blood glucose

following ingestion of rapidly digestible carbohy-

drates does not negatively impact food intake regula-

tion. In general,  50 g of sugar within 20–60 min of a

meal is sufficient to reduce meal intake.

0029Mechanisms controlling the regulation of food

intake remain poorly understood. It seems clear,

however, that the cause of obesity is an excess of

energy intake over expenditure. It is far too simple

to attribute its origin to the composition of the food

supply or of a particular food. Many foods and many

dietary habits probably contribute to this imbalance,

but for most the causative factor of greatest impact is

reduced energy expenditure in the form of physical

activity.

See also: Diabetes Mellitus: Etiology; Glucose:

Maintenance of Blood Glucose Level; Obesity:

Epidemiology; Etiology and Diagnosis; Sugar:

Sugarcane; Refining of Sugarbeet and Sugarcane;

Sweeteners: Intensive

5644 SUCROSE/Dietary Importance