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introduction to the New World was made by Colum-

bus, who carried the cane from the Canary Islands to

what is now the Dominican Republic on his second

voyage in 1493. By 1550, sugarcane was introduced

to Mexico, Brazil, and Peru.

0007 Because of its scarcity and expense, for much of

human history, sugar was considered a valuable medi-

cine and later a spice. It was not until the mid to late

eighteenth century that practical methods for sugar

extraction were developed, making cane sugar widely

available and less expensive.

Breeding Programs

0008 The productivity of any sugarcane industry is con-

stantly threatened by diseases, insect pests, and cli-

mate. To insure consistent, economical production,

new and improved, high-yielding sugarcane cultivars

are constantly needed to replace those removed from

production. Further, most sugarcane cultivars have a

finite life span of useful productivity. Prior to the early

1990s sugarcane was improved mostly by cultivar

substitution, making use of naturally occurring clones

(mainly S. officinarum). This gave improved yields

owing to better adaptation or greater inherent disease

resistance. In 1888, the fertility of sugarcane seed was

discovered in Java, Barbados, and Brazil, and before

the end of the century, organized breeding programs

were established in six countries. Initially, improve-

ments were realized using a procedure termed ‘nobi-

lization,’ whereby the hardy and disease-resistant, but

otherwise inferior wild cane types, i.e., S. spontaneum

and S. barberi, were crossed and back-crossed with

the noble canes, S. officinarum, which are character-

istically higher in juice quality.

0009Today, most sugarcane cultivars grown around the

world are trispecies hybrids that can be traced to only

a relatively few clones of the three species mentioned

above. The major objectives of most breeding

programs are to combine high-yield potential and

improved juice quality with disease resistance

and other important agronomic characteristics. Re-

current breeding and selection programs based on

yield potential have generally been highly successful.

Most of the economically important characteristics in

sugarcane are quantitative ones controlled by mul-

tiple genes. Therefore, large seedling populations are

required when attempting to develop new, high-

yielding sugarcane cultivars when selecting for as

many as 20 or more individual characteristics.

0010In an effort to broaden the narrow genetic base, a

basic or prebreeding program has been established

in many countries with its objective to broaden the

genetic base upon which contemporary cultivars are

bred. This base-broadening program makes most cul-

tivars less vulnerable to disease and insect pests and

increases their agronomic worth. However, the basic

breeding program is long-term and high-risk, and has

had success in only a few countries. It has had a

dramatic impact upon the sugar industry of Louisiana

in recent years with the release of three superior, high-

yielding cultivars for commercial planting. One of

fig0002 Figure 2 Flowering sugarcane in Cairns, Australia. Courtesy of Mary An Godshall and Alfred D French.

SUGAR/Sugarcane 5647

these cultivars, a BC

progeny of the S. spontaneum

clone US 56-15-8, now occupies approximately 70%

of the planted area. This cultivar alone has increased

productivity by over 30%, leading to a record yield of

sugar per unit area during the 1999–2000 harvest

season that approached 8.16 t of sugar per hectare

for a crop season which averages only 7–9 months.

0011 To augment traditional selection strategies, re-

searchers in various countries have developed species-

specific markers in recent years that allow for the

accurate selection of true hybrids of these different

species at the early seedling stage. In the past, it was

only through morphological traits that apparent true

hybrids were selected in the basic breeding programs.

However, in many cases it was later found that what

was thought to be a true hybrid was, in fact, a self or a

contaminant. This new molecular approach has given

plant breeders a powerful tool to select only those

genotypes that carry the desired markers.

0012 Each program is tailored for the needs of its specific

location, which can be quite different from country to

country. For example, in Louisiana, breeding goals

include development of early maturing cultivars

with cold tolerance suited for the very short growing

season of 9 months. These goals would be meaning-

less in a more tropical climate where other needs

predominate. Further, rarely will a cultivar selected

for one environment be adapted to the environment

of another area.

0013 Augmenting traditional approaches with new

molecular techniques fills a critical need in developing

these improved cultivars through wide hybridization

and genetic transformation. In recent years, research-

ers in several countries have been successful in

inserting genes into sugarcane plants that express

resistance to various diseases, insects, and herbicides.

Because of the great potential gains that can be

realized from molecular approaches in the develop-

ment of superior new cultivars, this long-term,

high-risk research also offers opportunities for the

twenty-first century. However, it is not envisioned

that these molecular approaches will replace trad-

itional breeding and selection in the development of

future high-yielding cultivars.

Diseases and Pests

0014 Sugarcane plants are subject to a number of bacterial,

fungal, and viral diseases. At any one time in any

given location, there are usually three or four preva-

lent diseases of major concern. The severity of infest-

ations increases and decreases in various parts of the

world depending on factors such as types of cultivars

grown and other control measures. The most recent

diseases to appear in the western hemisphere are: leaf

scald, caused by the bacterium Xanthomonas albili-

neans (Ashby) Dowson, which arrived in USA

(Florida) in 1967; smut, caused by the fungus Usti-

lago scitaminea Sydow, in 1978; rust, caused by the

fungus Puccinia melanocephala H. & P., in 1979; and

yellow-leaf syndrome, caused by a virus, in 1993.

0015Other important diseases include sugarcane

mosaic, a viral disease which caused severe losses

throughout the world in the earlier part of the cen-

tury, and ratoon-stunting disease, caused by the bac-

terium Clavibacterium xyli. Red rot, caused by the

fungus Collectotrichum falcatum, was once severe in

many parts of the world but now appears to be a

problem mainly in India.

0016Pests include rats – a severe problem in some areas

– nematodes, and a number of insects. The most

severe insect pests are the various types of borers,

i.e., the sugarcane borer, Diatrea saccharalis (F.),

and the eldana borer, Eldana saccharina, which

cause damage first by boring into the cane stalk,

then by providing entry points for other diseases

and, finally, by reducing cane and juice quality.

0017Various weeds cause problems in sugarcane culture

by competing for nutrients and crowding or over-

growing the young plants. Perennial grasses are the

most serious weeds, harboring insects and diseases.

Preemergent herbicides are commonly used for

control.

Control Measures

0018In recent years, detection of several of these diseases

has been made easier with the development of DNA-

based molecular diagnostic protocols. Timeliness of

diagnosis is important to the management of all dis-

eases; however, cultivar resistance through traditional

and molecular approaches still remains as the pri-

mary control mechanism.

0019Very little chemical treatment with fungicides or

other agents is used. Such measures are largely inef-

fective because the leafy canopy of the cane plant

prevents proper application, and such large amounts

would need to be applied as to be prohibitively ex-

pensive and environmentally unsound. (See Fungi-

cides.)

0020For some diseases, especially ratoon-stunting

disease, the seed cane is treated with hot water.

0021In recent years, experiments have progressed on the

use of biological control agents for long-term control

of insects. Examples include the Cordyceps fungus to

control white grubs, parasitization with the wasp

Apanteles flavipes to control borer, and the fungus

Metarhizium anisopliae for leaf hopper control.

0022The sugarcane borer, Diatraea saccharalis (F.), and

the Mexican rice borer, Eureuma loftini (Dyar), are

5648 SUGAR/Sugarcane

major insect pests of the mainland USA sugarcane

industry. However, in 1986 a recurrent selection pro-

gram was initiated in Louisiana to develop sugarcane

cultivars with resistance to these two stalk borers.

Plant resistance as well as biological control have

become increasingly important as tactics used in inte-

grated pest management (IPM), thus reducing the

need for chemical pesticides and increasing profit

margins for farmers. During the past 10–15 years,

the need for chemical pesticides has been reduced

from four applications per unit area per year to less

than one application per unit area per year, with the

use of more resistant cultivars and IPM.

Culture

0023 Sugarcane grows in the warm, humid tropics and

subtropics. It needs at least 600 mm of annual rainfall

but responds well to irrigation where rainfall is

limited.

0024 Propagation is asexual, accomplished by cuttings

known as sets or ‘seed cane’ which contain at least

one bud. It is also propagated sexually by pollination,

but this is usually seen only in breeding programs

since sugarcane is a polyploid hybrid and does not

breed true.

0025 Sugarcane normally requires large inputs of chem-

ical fertilizer, especially nitrogen, in order to maxi-

mize yields; however, excellent yields can be obtained

with minimum cultivation.

0026 Types of cane harvesting are determined by terrain,

soil types, and the availability and cost of labor.

Methods range from manual cutting to full mechan-

ical harvesting, which includes whole-stalk and billet-

cane (combine) harvesting. In some parts of the

world, the cane is briefly burned to remove the dry,

trashy leaf residue. Burning also helps to reduce the

number of field pests, such as snails, rats, and insects.

The cane may be topped or not, burned standing or

lying cut in the field, or taken green (unburned) to the

mill.

0027 Harvest seasons vary with location, ranging from

mid-June to December in Queensland, from mid-

October to March in Texas and Florida, and early

October to the end of December in Louisiana, which

is one of the shortest harvest seasons in the world. In a

few tropical areas, the cane may be harvested all year

around. Table 1 shows the harvest dates for several

countries.

Maturation and Use of Ripeners

0028 In nature, the cane ripens, or matures, when growth

slows and the synthesis and storage of sucrose occur.

Ripening is influenced by many factors, with the most

important being the age of the cane, incident sunlight,

temperature, and rainfall. Cultivars differ in their

optimum ripening time, some being considered

early-maturing and some late-maturing.

0029The use of chemical ripeners has increased since the

introduction of glyphosine in 1972. Glyphosine, gly-

phosate, mefluidide, and ethepon are the compounds

most widely used. The harvest is timed to coincide

with the maximum level of sucrose in the mature

stalks, and chemical ripeners are used to maximize

the sucrose-producing potential of the cane stalks,

especially under adverse ripening conditions. Rip-

eners are not able to induce the production of more

sucrose than is inherent to the cultivar, nor are they

economically effective when natural ripening condi-

tions are optimum.

Production of Raw Sugar

0030The harvested sugarcane cannot be stored for very

long without deteriorating, so it is converted to raw

sugar with as little delay as possible. The sugar is

contained in the stalk juice, ranging in concentration

from 15% to 20% sucrose. The juice also contains a

number of other constituents, such as starch and

other polysaccharides, bits of fiber, flavonoid and

anthocyanin pigments, protein, amino acids, aconitic,

and other organic acids and salts. The purpose of

sugar manufacture is to separate the sugar from

these other components and to crystallize it in as

pure a form as economically feasible.

0031The first stage of sugar manufacture is the produc-

tion of raw sugar, which occurs in the sugar mill or

factory. Juice is extracted from the stalks by either of

two processes: milling, which is the more common,

or diffusion. In either process, the cane tissue is

sufficiently disrupted by cutting, shredding, grinding

or ‘fiberizing’ to achieve 95–97% extraction of avail-

able sucrose. (See Sucrose: Properties and Determin-

ation.)

0032The raw cane juice is turbid and acidic, with pH in

the range of 5.3–5.7. The first stage of sugar produc-

tion is clarification (or purification) of the juice,

designed to remove soluble and insoluble impurities

and to inactivate enzymes that hydrolyze sucrose (in-

vertase). Clarification is carried out by the addition of

lime and flocculents to the heated cane juice. This

coagulates and precipitates insoluble and colloidal

material and raises the pH to near neutral. Increasing

the pH of the juice helps to stabilize the sucrose

against acid hydrolysis. After filtration, the clarified

juice is concentrated by evaporation into crystalline

raw sugar. In recent years, several variations on the

above process have been developed to improve yield

and product quality. Among these are the use of

SUGAR/Sugarcane 5649

enzymes to reduce problematic polysaccharides. For

example, dextranase enzyme is used to reduce the

amount of dextran, which is caused by infection

with the bacterium Leuconostoc mesenterioides,and

amylase is sometimes used to decrease the amount of

starch in the juice from some high-starch cultivars.

Expensive enzymes such as these are used only on an

‘as-needed’ or emergency basis.

0033 During processing, the cane juice changes color

from dark green to golden brown owing to various

color-forming reactions, the most important ones

being enzymatic and nonenzymatic browning and

polymerization of polyphenolic acids, the Maillard

browning reaction between reducing sugars and

amino acids, and the caramelization reaction caused

by thermal degradation of sugars. Manufacturers

try to maximize sucrose yield and minimize the reac-

tions that produce color or cause sucrose loss. (See

Browning: Nonenzymatic; Caramel: Properties and

Analysis.)

0034 In the USA and some European countries, raw

sugar is considered inedible because it is not made

according to the strict sanitary codes established in

those countries. However, in many other parts of the

world, raw sugar is sold directly to the consumer. The

composition of raw sugar is shown in Table 2.A

special type of raw sugar, called turbinado sugar, is

produced for the edible market in Europe and North

America.

0035 In terms of bulk, the major coproduct of milling is

bagasse, the fibrous residue of the stalk. Although

some of it is used in paper-making, as a chemical

feedstock and in cattle feed, its principal use is as an

energy source for the mills, allowing most cane fac-

tories to be partially or totally energy-self-sufficient.

In some areas cogeneration of electricity is also

possible.

0036 Raw sugar is a commodity sold on the world

market. Many rules and regulations control its sale,

its cost, and its transport around the world. Raw

sugar is exported from producing areas to refineries

in industrialized countries for conversion into highly

purified white sugar.

Specialty Products from Sugarcane

0037While the major product from sugarcane is white,

granulated sugar, the process also lends itself to the

production of several specialty sweeteners. Sugarcane

is uniquely suited, by virtue of trace components

present in the juice and the reactions that occur

during processing, to produce sugars with desirable

flavors and colors. The latter range from light yellow

to dark brown, and flavors include a range of molas-

ses and browned/caramelized types.

0038The specialty sweeteners from sugarcane include

factory (mill) products such as turbinado sugar, edible

molasses, Demerara sugar, muscovado sugar, planta-

tion white sugar, sugarcane syrup, and dried cane

juice. In the last 5 years or so, organic sugar has

come on the market in various locations. Specialties

from refineries include brown sugar, yellow sugar

(popular in Canada), golden syrups, refinery syrups,

and molasses. Less common specialties include canned

or packaged, pasteurized cane juice, canned cane

stalks, dehydrated molasses, and liquid brown sugar.

0039Brown sugar, which is produced in refineries, is a

very fine grain sugar which is enveloped in a thin film

of dark syrup and may range in color from light

yellow to very dark brown. It is produced in either

of two ways. The traditional method is to crystallize it

from a refinery syrup selected for its color and flavor.

The second, more energy-efficient way is to coat

white sugar crystals with cane syrup or molasses.

The latter method can be used to produce brown

sugar from beet sugar.

0040The last decade has also seen great changes in the

production of plantation white sugar, which is a white

sugar produced directly at the mill, in lieu of raw

sugar. This sugar is not of as high quality as refined

sugar, having slightly higher color, ash, moisture, and

reducing sugar content, but it is acceptable for almost

all domestic applications. It has the advantage that its

production is much less expensive than that of refined

sugar, and it can be made in existing raw sugar mills

with a minimum of redesign of equipment. Currently,

most plantation white sugar is used within the coun-

try of production, but several countries, notably

Brazil, have in recent years developed a worldwide

trade in plantation white sugar.

See also: Browning: Nonenzymatic; Caramel: Properties

and Analysis; Fungicides; Sucrose: Properties and

Determination

tbl0002 Table 2 Composition of raw sugar

Component Range of concentration

Sucrose 96–99%

Glucose 0.3–0.6%

Fructose 0.3–0.6%

Moisture 0.1–0.5%

Ash 0.1–0.5%

Starch 50–400 p.p.m.

Other polysaccharides 800–1500 p.p.m.

Insoluble matter (soil and

vegetable particles)

200–500 p.p.m.

Color 800–3000 ICUMSA units

ICUMSA, International Commission for Uniform Methods of Sugar

Analysis. It is the absorbancy index of the solution  1000:

420

 1000

cell length ðcm ÞConc: ðgml

1

5650 SUGAR/Sugarcane

Further Reading

Chen JCP and Chou CC (eds) (1993) Cane Sugar Hand-

book, 12th edn. New York: John Wiley.

Clarke MA and Godshall MA (eds) (1988) Chemistry and

Processing of Sugarbeet and Sugarcane. Amsterdam:

Elsevier Science.

Heinz DJ (ed.) (1987) Sugarcane Improvement through

Breeding. Amsterdam: Elsevier Science.

F.O. Lichts World Sugar and Sweetener Yearbook 1998/99

(1998) (F.O. Lichts World Sugar Statistics 1998/99).

Ratzeburg, Germany: F.O. Licht.

Pan Y-B, Grisham MP, Burner DM, Legendre BL and Wei Q

(2000) DNA-based molecular diagnostic protocols for

sugarcane bacterial diseases. In: Solomon S (eds) Sugar:

Agro-Industrial Imperatives (Vision for 21st Century).

New Delhi: Oxford/IBH Publishing.

USDA (1999) Sugar and Sweeteners: Situation and Outlook

Yearbook. Rockville, Maryland: US Department of Agri-

culture, Commodity Economics Division, Economic

Research Service.

The internet is now a source of information about sugar and

sugar statistics. A few recommended sites are:

US Department of Agriculture, Foreign Agriculture Service

http://www.fas.usda.gov/htp2/sugar/1999/November/

toc.html

Sugar and sweetener summary reports http://usda.mann-

lib.cornell.edu/reports/erssor/specialty/sss-bb/

Sugar Information http://www.sugarinfo.co.uk/index.htm

Louisiana State University http://www.lib.lsu.edu/special/

sugar/intro.html

Sugarbeet

M A Clarke, Sugar Processing Research Institute

Incorporated, New Orleans, LA, USA

M F G Cleary, Holly Sugar Corporation, Colorado

Springs, CO, USA

This article is reproduced from Encyclopaedia of Food Science,

Introduction

0001 Total world sugar production in 1990–91 was

112.6 10

t, of which 41.2 10

t were produced

from sugarbeet, and the rest from sugarcane. Some

35% of world beet sugar is produced in the EC, and

9% in the USA. Table 1 lists areas, yields, and sugar

yield for the 10 major sugarbeet-producing countries

based on (1989 to 1991 data). Sugarbeet is grown in

many climates, from temperate (southern California,

Spain, Italy) to relatively cold climates (North

Dakota, Finland). In general, sugarbeet is converted

directly to white sugar, refined quality, although some

eastern European areas still make an intermediate

raw sugar because of lack of processing facilities.

Costs of production vary widely with climate, yield,

and socioeconomic factors. Average production costs

(grower cost) and factory cost (processor cost) are

shown in Table 2 for the USA, an intermediate-cost

producer.

Composition

0002The composition of sugarbeet is shown in Table 3.

Sugarbeet, being a root, has a much higher level of

nitrogen compounds than does sugarcane, and beet

processing is geared to removing these, and prevent-

ing them from contributing to color and odor com-

pounds. Composition is of vital importance to sugar

yield because soluble nonsucrose constituents impede

crystallization of sucrose by complexing with sucrose

and carrying it into residual molasses. Each kilogram

tbl0001Table 1 World sugarbeet statistics: area harvested, yield, and

production for leading producing countries

Country and year Area

harvested

(10

ha)

Sugarbeet

yield

(t ha

1

)

Sugar

yield

(t ha

1

)

Share of world

beet sugar

production (%)

Former Soviet Union

1989–90 3344 29.1 2.85 24.4

1990–91 3267 24.9 2.80 22.2

Germany

1989–90 609 44.2 6.71 10.4

1990–91 619 49.0 7.54 11.3

USA

1989–90 524 43.5 6.00 8.0

1990–91 558 44.8 6.27 8.5

France

1989–90 427 56.0 9.85 10.7

1990–91 474 52.4 10.01 11.5

Turkey

1989–90 350 31.2 3.94 3.5

1990–91 370 35.1 5.14 4.6

Poland

1989–90 423 34.0 4.41 4.8

1990–91 440 38.0 4.94 5.3

Italy

1989–90 290 57.2 6.48 4.8

1990–91 262 44.3 6.06 3.9

China

1989–90 569 16.2 1.35 2.0

1990–91 730 19.9 1.78 3.2

1989–90 194 41.2 7.10 3.5

1990–91 192 41.7 6.02 3.3

The Netherlands

1989–90 128 56.3 9.70 3.2

1990–91 125 69.7 10.71 3.3

World

1989–90 8620 35.9 4.54 100.0

1990–91 8726 34.7 4.72 100.0

Source: Foreign Agricultural Service, US Department of Agriculture.

SUGAR/Sugarbeet 5651

of nonsucrose constituents in sugarbeet juice can

carry 0.65–0.85 kg of sucrose to molasses, removing

it from the yield of crystalline sugar. Plant breeders

have bred for high sucrose in beet to the point where

selection for lower specific nonsucrose components

(sodium, potassium, amino nitrogen) can generate

greater total sucrose yields. (See Sucrose: Properties

and Determination.)

Origin, Plant Breeding, and Cultivation

0003 Sugarbeet has been grown for sugar (sucrose) produc-

tion only since the late eighteenth century, when

Achard in Europe identified the ‘white Silesian beet’

as a source of sugar, and Napoleon encouraged breed-

ing and processing research, to provide a home-

produced alternative to cane sugar, which required

shipment from the West Indies.

0004Sugarbeet, grown from seed, is a biennial plant

which accomplishes vegetative growth in its first

year and seed production in the second. For sugar

production it is harvested at the end of the first year

of growth, after a frost-free (preferably) period of 5–6

months, in areas with annual rainfall of some 20 cm.

Irrigation is used in some areas, e.g., north-western

USA. Sugarbeets are often used in crop rotation, as

their deep roots bring up nutrients from lower levels

of soil, to become available for alternate crops, and

because they cannot be planted in the same field more

than once every 3–4 years without risk of attack by

nematodes. Beets for seed are grown in nonsugar-

producing areas, notably in Oregon, where most US

and European companies operate joint-venture seed

companies with the purpose of maximizing germ-

plasm resources.

0005Seed is, and has been since the 1940s, all mono-

germ hybrid, which permits mechanical planting and

harvesting. The selected monogerm, male-sterile,

inbred line and the multigerm pollinator (chosen for

other desirable characteristics) are initially multiplied

separately; the former is planted in strips together

with the fertile monogerm complementary line. Foun-

dation seed produced by the male-sterile inbred fur-

nishes the seed parent for the hybrid variety, which

again is grown in strips with foundation seed of the

pollinator. Monogerm hybrid seed is harvested only

from the male-sterile parent, while the pollinator is

destroyed soon after flowering.

0006The major varieties currently grown in the USA

are shown in Table 4. Varieties must be tested in

semicommercial or commercial trials for several

years after development to receive test market

approval.

Harvest Practice

0007Clean, unbroken beets, free of leaves, trash, and

rocks, are the primary objective. Grower contracts

can penalize noncompliance and usually include a

right of refusal for beet not fit for processing. This

option is rarely exercised in North America, except

when beets are so severely degraded as to stop the

process completely.

0008Harvest dates are normally agreed upon prior to

planting, with premiums for early and/or late harvest

deliveries to compensate the grower for beet low in

sugar content and tonnes per hectare (immature), or at

risk from weather, respectively. Harvesting normally

tbl0002 Table 2 Sugarbeets: US production and processing costs per

net ton of sugarbeets and pound of refined sugar (1989 crop)

Item Dollarsper ton Cents perpound

Production costs

Variable cash expenses 20.27 7.881

Fixed cash expenses 8.00 3.110

Operating capital 0.93 0.362

Nonland capital 1.02 0.397

Net land return 8.18 3.180

Unpaid labor 1.78 0.692

Total 40.19 15.626

Processing costs

Variable cash expenses 22.47 8.735

Fixed expenses 3.45 1.342

General and administrative 1.93 0.750

Pulp drying and marketing 3.43 1.335

Total 31.28 12.162

Total production and

processing costs

71.47 27.788

Credits

Dried pulp 6.92 2.691

Molasses 2.31 0.898

Other 0.51 0.198

Total 9.74 3.787

Net production and

processing costs

61.73 24.001

Yield per planted acre (ton) 19.4

Recovery per net ton of

beets (lb)

257.2

tbl0003 Table 3 Composition of sugarbeet

Component Content (%)

Juice c.9

Insoluble matter (marc) c.5

Water, chemically bound c.3

Soluble solids 11–25

Sucrose in solids 87.5

Sucrose in beet 10–22

Nonsucrose substances soluble in juice

Organic nitrogen compounds c.44

Nitrogen-free organic compounds 36

Inorganic compounds 20

5652 SUGAR/Sugarbeet

takes place in September to November, except in

some areas of California where a second crop is har-

vested in the spring. The combined harvest and pro-

cessing strategy accounts for both the ‘optimum

harvest window’ for the grower, and the beneficial

impact of increased throughput on processor profit-

ability.

0009 Commonly used machines can harvest four to six

rows simultaneously, and up to 1000 t per day. None

the less, smaller machines (one and two rows) are

abundant, and there are still areas where beets are

harvested by hand at a rate of less than 10 t per

worker per day. The harvester is normally pulled

behind a tractor which dumps the harvested beet

into an open lorry alongside. Three basic operations

are performed: removal of the beet from the ground;

removal of the leaves and, perhaps, a portion of the

top of the root; and a modest separation of dirt and

trash from the root.

0010Complete removal of leaves is essential, whether

before the beet is taken from the ground, or after the

beet is lifted. Further removal of a portion of the top

of the root is arguably of benefit. The portion that is

removed typically displays 67% of the sugar concen-

tration of the main root and has a higher impurity

load; its inclusion would reduce both grower pay-

ment and processing profitability. On the other

hand, a sizable wound is inflicted, which may lead

to sugar losses between harvest and processing.

Effect of Ambient Temperature

0011The technical value of the beet decreases exponen-

tially if the root is subjected to repeated freeze–thaw

tbl0004 Table 4 Sugarbeet varieties grown in specific areas of the USA

Variet y Area

RRV MI-OH CO-NE WY-MT ID-OR TX CA

Mono-Hy E4 X

Mono-Hy E9 X

ACH 185 X

KW-1745 X

Hilleshog 5135 X

Hilleshog 8277 X

Hilleshog 8351 X

Maribo Ultramono X

Maribo 410 X

Maribo 403 X

Maribo 875 X

Betaseed 2988 X

Betaseed 2398 X

Betaseed 3145 X

Betaseed 3265 X

Monohikari X X

Hilleshog 1605 X

Hilleshog 55 X

Betaseed 3778 X

Hilleshog R2 X

Hilleshog D2 X

HH 50 X

ACH 191 X

PM 9 X

WS 88 X

MHR 2 X

MH 55 X

HM1 TX-9 X

HH 57 X

HM1 1803 X

SS-NB3 X

HH 37 X

HH 45 X

SS-NB2 X

Betaseed 4757 X

RRV, Red River Valley; MI–OH, Michigan–Ohio; CO–NE, Colorado–Nebraska; WY–MT, Wyoming–Montana; ID–OR, Idaho–Oregon; TX, Texas;

CA, California.

Data courtesy of Beet Sugar Development Foundation, Denver, Colorado, USA.

SUGAR/Sugarbeet 5653

cycles, with ambient temperature falling below

5



C. Irreversible tissue damage occurs, the vascular

system collapses, and secondary infections consume

the sugar. The first hard freeze will normally kill the

leaves while the root remains undamaged, and, if the

soil temperatures are reasonably high and a variety

has been chosen which ‘sits down’ in the soil, the crop

can withstand several nights of 5



Cto10



temperatures. Some cold-temperature growing areas

target this period to accelerate the daily delivery rate

to the factory, from about 1% of the crop to up to

10% of the crop per day.

0012 Similar phenomena occur in beets which have been

subjected to temperatures in excess of 40–45



C for a

number of days. Since the respiration rate has already

been accelerated by heat, and soilborne infections and

diseases thrive in warm soils, tissue degradation and

technical losses occur much more rapidly. Autumn

harvests around the Mediterranean and spring

harvests in California are occasional victims of this

plague.

Sampling

0013 As beets are delivered and received by the pro-

cessor, a representative sample is taken in order to

determine, ultimately, the amount that will be paid to

the grower. The sampling procedure varies from elab-

orate cross-sectioning of the lorry and subsequent

sample-splitting, to a simple ‘grab sample’ of the

falling stream of beet. Samples are evaluated in a

laboratory usually operated by the processor but

open to inspection by the grower. Parameters

normally include sugar content, percentage dirt and

trash (tare) and, occasionally, other analyses.

0014 The tare is the portion of the delivery which, by

contract, the processor is not obliged to pay for. It

always includes rocks, leaves, and trash, but may also

include a portion of the top root which the grower

had agreed to ‘scalp’ from the beet. Once the percent-

age is determined in the laboratory, the delivered

weight is adjusted accordingly. Dirt and trash typic-

ally contribute 1–2% to the tare value, but difficult

harvest conditions may drive this contribution to over

10%. ‘Top tare,’ if applicable, will normally fall into

the 3–5% range.

0015 Sugar content of mature, healthy beet is between

10% and 22% (Table 3) depending on agricultural

inputs: variety, disease pressure, climate, and harvest

conditions. Grower payment is linearly tied to sugar

content, with a multiplier based on the market value

of sugar. The typical participating payment scale in

the USA returns 60% of the net market value of

the recovered sugar to the grower. Some contracts

include a premium for exceptionally high sugar

concentrations based on the assumption that recovery

will increase accordingly.

0016Analyses for nonsucrose components may be run to

estimate the amount of impurities which affect yield

on crystallization. Most common are sodium, potas-

sium, and amino nitrogen; they are used ubiquitously

in breeding beet varieties, and occasionally in both

Europe and North America to adjust the grower

payment.

Storage of Beet

0017After beets are removed from the ground, they can

be processed immediately, stored for a few weeks,

during which time normal respiration losses are

tolerated, or put into long-term storage which re-

quires special equipment and/or techniques to main-

tain the beet for several months. Respiration losses

during the storage of healthy beet are typically 0.15%

sugar per week. Another strategy is to increase the

beet-processing capacity of the factory and store an

intermediate syrup.

0018When beets are stored in piles for up to 160 days,

special precautions may range from simply orienting

the pile to minimize exposure to sunlight, to the use

of fully enclosed ventilated sheds which can contain

90 000 t of beet. Between these extremes are the use of

straw or plastic to cover the piles, and the use of half-

round ducts to ventilate beet piles. Typical piles con-

tain 50 000–100 000 t of beet, with a trapezoidal

cross-section 50–65 m wide at the base and a height

of 6–9 m, depending on storage conditions.

0019Clean, unbroken beets, with a root temperature

below 10



C, are required to assure the proper air

flow and cooling which prevent the natural respir-

ation of the beet from heating the pile. Piles are

monitored to detect such hot spots. Ideally, storage

should minimize respiration rate without freezing the

tissue but, in practice, the outer layer of the pile often

suffers severe deterioration to a depth of about 50 cm.

Forced-air ventilation may be used intentionally to

freeze the entire pile where the climate allows this to

be accomplished continuously over a period of a few

days: this requires daily temperatures below 10



for 4 or 5 days. Such beets are not subject to respir-

ation losses, but must remain frozen until they are

processed.

0020Regardless of storage conditions, beets enter the

factory process in a flow of water through the flume

during which, allowing for the natural buoyancy of

the root, rocks and trash are separated. Some washing

is effected during this process, but all processes are

supplemented with a beet washer, prior to slicing the

beet. Water from the washer is returned to the flume

loop, which typically includes a system to remove

5654 SUGAR/Sugarbeet

suspended solids, lower biochemical oxygen demand

(BOD) and chemical oxygen demand (COD), and

reuse the water.

Factory Processing

0021 Sugarbeet processing is illustrated in Figure 1. The

complete sugarbeet-processing operation involves a

number of unit operations, including the following:

0022Diffusion (dried beet pulp – animal feed copro-

duct).

0023Carbonation (purification).

0024Evaporation (concentration).

0025Crystallization (saleable white sugar; also molas-

ses coproduct used as animal feed and fermenta-

tion feedstock).

After washing, beets are sliced into V-shaped cos-

settes, about 3 cm by 4.5–7.2 cm. This shape ensures

maximum surface area for sugar extraction. Cossettes

are introduced into a countercurrent continuous dif-

fuser that may be one of several designs: horizontal

drum, sloped vat, or vertical-cylindrical tower. All

designs involve a mechanism to transport sugarbeet

cossettes in a direction against the flow of hot water

extractant, and extract some 98% of the sugar

(sucrose) in the beet. Sugarbeet cell walls are

heat-denaturedto enhance diffusion of sugar from

the plant cells to the lower concentration of sugar in

the aqueous extractant. Wet beet pulp, discharged

from the diffuser at approximately 92% moisture, is

pressed mechanically to reduce beet pulp moisture to

approximately 76%, and either air-dried under ambi-

ent temperatures (in California) or dried in direct gas,

oil, or coal-fired rotary drum driers to a moisture

content of approximately 10%. Pulp has long been

sold as an animal feed, but in recent years it has been

purified and sold as a food fiber, for breakfast cereals.

Juice from the diffuser (diffuser juice or raw juice)

contains approximately 12% sucrose by weight, to-

gether with 2% soluble impurities, soluble and semi-

soluble colloidal proteins, pectins, and saponins

extracted from the cossettes; it is heated to 85



prior to purification with lime and carbon dioxide,

called carbonation.

0026In this carbonation clarification, semisoluble col-

loidal materials are coagulated and precipitated as

insoluble salts. Potassium and sodium salts of oxalic,

malic, and citric acids, and phosphates and sulfates

are precipitated as insoluble calcium salts. Milk of

lime (a suspension of calcium hydroxide) and carbon

dioxide are added continuously and concurrently to a

diffusion juice in a carbonation tank, with a retention

time of 12–15 min at 85–88



C. Treated juice is then

sent to a clarifier for separation of the precipitated

impurities. Thickened underflow mud from the clari-

fier is filtered on vacuum, rotary drum filters and

washed to minimize sugar loss.

0027Lime and carbon dioxide are produced from limer-

ock (calcium carbonate) at each factory in a coke or

natural-gas-fired, vertical-shaft Belgium-type lime

kiln, or in a gas-fired, horizontal, rotary drum-type

kiln where waste lime is reburned. Carbon dioxide

is reclaimed from the kiln for direct use in the

Beet receiving

and storage

Washing

Slicing

Diffusion

First

carbonation

purification

Clarification

purification

Second

carbonation

purification

Filtration

Sulfitation

Evaporation

Filtration

Molasses

White sugar

boiling and

centrifugal separation

Raw sugar

boiling and

centrifugal separation

Molasses

storage and

shipping

Pulp

pressing

Pulp

drying

Pulp storage

and shipping

Driers

Screens

Bulk storage

and shipping

fig0001 Figure 1 Outline of sugarbeet factory process. Source: Holly

Sugar Corporation, a subsidiary of Imperial Holly Corporation,

Colorado Springs, USA. Reproduced from Sugar: Sugar Beet,

Encyclopaedia of Food Science, Food Technology and Nutrition,

Macrae R, Robinson RK and Sadler MJ (eds), 1993, Academic

Press.

SUGAR/Sugarbeet 5655

lime–carbon-dioxide first carbonation purification

tank. Approximately 2% of lime on sugarbeets is

used for purification and clarification.

0028 Clarified overflow juice (thin juice) is then sub-

jected to a second treatment with carbon dioxide to

reduce residual lime salts concentration. Calcium car-

bonate precipitate is filtered from the juice by use of

pressure filters. Sulfur dioxide is added to the filtered

juice to minimize color formation during subsequent

processing steps. The thin juice, after all colloidal

impurities and approximately 35% of the soluble

impurities have been removed, is concentrated from

about 13% dissolved solids (13



Brix) to approxi-

mately 60–65% dissolved solids in energy-efficient

quintuple-effect evaporators.

0029 Steam at all beet sugar factories is produced in

relatively low-pressure (17.5–28 kg cm

2

) boilers.

This steam is passed through a turbine to produce

electricity for factory use. Exhaust steam from

the turbine is used for heating, evaporation, and

crystallization of sugar in the latter stages of the

process.

0030 Thick juice from the evaporators is concentrated

and sugar is crystallized in a three-stage process. The

first vacuum-pan crystallization produces white

sugar, separated from mother liquor (massecuite) in

basket-type batch centrifuges, in which crystals are

washed with hot water. Second and third vacuum-pan

crystallizers produce lower-purity raw sugars, which

are redissolved after separation of the massecuite

in continuous conic-basket centrifuges developed

specifically for the sugar-processing industry.

0031 White sugar, discharged wet from the batch centri-

fuges, is dried in rotary hot-air driers (granulators) to

a moisture content of approximately 0.02%. The

white refined sugar produced is 99.96% pure as a

result of successive purification by diffusion, lime–

carbon-dioxide purification, and triple crystallization

in the batch vacuum-pan crystallizers.

0032 The mother liquor recovered from the last three

vacuum-pan crystallizers is exhausted of further raw

sugar crystals under standard atmospheric condi-

tions. The massecuite reclaimed from this process

is a molasses coproduct, and approximately 60%

of the solid material is sucrose. The ratio of nonsugar

impurities to sugar prevents further crystallization of

sugar using conventional processing technology.

0033 Sugarbeet processing is a seasonal operation, be-

ginning with beet harvest, which must be completed

before beets freeze in the ground, and continuing

through processing of stored beets. Some factories

process additional beets to syrup, or thick juice,

which is then stored in tanks and processed after

beet input is complete. A longer operating season

reduces the fixed costs of a factory.

Molasses Desugarization

0034In the last decade, a new process has been developed

and widely applied in the North American, Japanese,

and Finnish beet sugar industries. Molasses desugar-

ization, accomplished by ion exclusion in which the

final molasses is passed over ion exchange resins

which separate sucrose from other molasses compon-

ents, allows continuous production of a high-sucrose

product stream and a desugarized molasses stream,

and can increase a factory’s sugar production by

10%, with no increase in incoming beet.

Problems of Waste Disposal

0035Leaf and root material which have been removed in

the field during the harvest are normally reincorpor-

ated into the soil as green manure. Occasionally, live-

stock are allowed to forage directly on this material.

Trash and beet pieces recovered from the flumes are

also used as cattle feed, either directly or chopped

with pulp for drying.

0036Most factories operate a self-contained system to

handle the vast amounts of water used for beet trans-

port and cleaning. Two to four million liters of water

per day for a factory processing 5000 t day

1

are

settled to remove suspended solids and to reduce the

COD and BOD, usually through an extensive lagoon

system, and reused. (See Effluents from Food Process-

ing: Composition and Analysis.)

0037Precipitated calcium carbonate, which contains

10–15% organic and phosphate impurities, is pro-

duced at a rate of about 4–5% (w/w) of beet. The

most up-to-date processes yield material which can be

directly used for soil amendment or as an animal feed

supplement. Less modern factories will allow this

material to dry outside before sale.

See also: Effluents from Food Processing: Composition

and Analysis; Sucrose: Properties and Determination