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

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Endocrine System

0006Growth hormone and insulin-like growth factors

are low in PWS. Gonadotrophins, estrogen, and/or

testosterone are usually low in PWS. Increased vis-

ceral fat is one cause of glucose intolerance and may

lead to diabetes mellitus.

0007Growth hormone treatment is licenced for children

with PWS in many countries, including the UK, USA,

and Scandinavia. In addition to aiding linear growth,

body composition is altered by increasing the fat-free

to fat mass ratio. Early indications from ongoing

studies show that adults can also benefit from this

treatment.

Neurotransmitters and Peptides

0008Several of these have been found to be abnormal in

PWS. Plasma cholecystokinin (CCK) is raised, yet

there is a resistance to the satiety effects. Gamma-

aminobutyric acid (GABA) has also been found to

be raised in plasma. Leptin levels have been found

to be different from those in matched controls in

several studies, although the significance of alter-

ations is as yet inconclusive. Increased turnover of

serotonin in PWS has been found, and this may

contribute to the loss of satiety.

The Syndrome and its Management

0009The condition is characterized by two distinct phases

with multisystem involvement. The hypothalamus is

the probable site of major dysfunction as there are

numerous alterations to the body’s homeostatic

mechanisms.

0010Decreased fetal movement is common. Infants pre-

sent at birth with severe hypotonia. They are fre-

quently unresponsive to their own needs or to their

environment.

0011Failure to thrive during Phase 1 is common; special

feeding measures, e.g., nasogastric tube feeding, are

usually necessary, but respiratory support, such as

artificial ventilation, is not.

0012Phase 2 is characterized by hyperphagia (overeat-

ing), usually developing between 1 and 6 years of age

– although this may be earlier or later – resulting in

life-threatening obesity unless energy intake is

restricted. The phenomenon of food-seeking and

stealing, and surreptitious eating, exhibited in

this population is poorly understood by many profes-

sionals.

0013Motor and language development are delayed.

Learning difficulties range from very mild to severe.

0014The placid infant develops into a smiling, friendly

child. Most children and adults are loving and

tbl0001 Table 1 Characteristics of Prader–Willi Syndrome (PWS)

Regulatory

Hypotonia (poor muscle tone)

Hypogonadism (undersized or nonexistent genital organs)

Hypoactivity

Hyperphagia (overeating)

Poor temperature control

Decreased pain threshold and sensitivity

Sleep disturbances

Respiratory disturbances

Rumination

Physical

Distinctive facial characteristics: almond-shaped eyes, high

forehead, small downturned mouth, slightly open mouth,

prominent nasal bridge

Central obesity

Small hands

Straight ulnar border

Small feet

Dental abnormalities: crowded teeth, poor dental enamel

High palatal arch

Myopia

Strabismus

Cognitive

Learning disabilities

Speech and language delay

Poor articulation

Perseveration (repetitive speech)

Argumentative

Food-seeking

Food-stealing

Compulsions

Stubbornness

Temper outbursts or tantrums

Aggressive behavior to objects and others

Self-injury

Skin-picking

Emotional lability

Other characteristics frequently present in PWS

Obesity

Pale skin

Increased bruising

Reduced motor control

Poor dentition

Reduced salivary flow

Thick, sticky saliva

Absent or irregular menstruation

Undescended testes

Diabetes mellitus

Scoliosis

Osteoporosis

Epilepsy

Narcolepsy

Heart compromise

Cellulitis

Respiratory compromise

Bowel irregularities

Mental health (illness): depression, psychosis, schizophrenia

Modified from Greenswag LR and Alexander RC (1995) Management of

Prader^Willi Syndrome, 2nd edn. New York: Springer-Verlag; and Waters J

(2001) Babies and Children with Prader^Willi Syndrome, revised edn. USA:

Prader–Willi Syndrome Association.

1766 DEVELOPMENTAL DISABILITIES AND NUTRITIONAL ASPECTS/Prader–Willi Syndrome

warm; nevertheless, behavior problems are fre-

quently exhibited, e.g., short-lived temper outbursts,

stubbornness, manipulative tendencies, including

attention-seeking and obsessions, frequently focused

on, though not restricted to, food. Sometimes such

problems develop into major mental health issues.

There appears to be an increased risk of developing

recurrent psychoses; these must be distinguished

from behavioral phenotypes. Perseveration (repeti-

tive speech) is common; it is unclear if this has an

underlying physical or psychiatric basis.

0015 Almost without exception, adults are unable to live

completely independent lives.

Prognosis

0016 Gross obesity, leading to premature death, is avoid-

able and not inevitable. Individual treatment plans

and/or programs should be devised and provided in

a supportive environment. The management program

should include good dietary management at an

appropriate energy intake level, to insure weight is

kept within reasonable limits.

0017 The most significant development in recent years is

the beneficial effect of growth hormone treatment.

Medical Complications

0018 As well as affecting life expectancy, many of these

medical complications not only affect health but can

precipitate an alteration in living conditions, e.g., to

emergency nursing care; crisis management rarely

provides the best alternative living environment.

Diabetes Mellitus (DM)

0019 Diabetes mellitus has been frequently reported –

almost entirely Type 2 (noninsulin-dependent) –

directly linked to obesity. Until weight loss occurs,

insulin therapy may need to be prescribed. Blood

pressure control, along with no smoking, may be

more difficult to achieve in the PWS population.

Osteoporosis

0020 The recorded incidence of osteoporosis appears to be

on the increase; this may be due entirely to a longer

life span, influenced by lack of hormonal secretions in

females, or may simply be more readily recognized as

a complication of PWS.

Skin-Picking

0021 Skin-picking can be severe. Infected sores, which

were originally minor spots, bites, or operation

scars, remaining as open wounds for months or even

years, may be related to reduced pain threshold.

Sleep Apnea

0022Oxygen deprivation leads to sleep disturbances and

somnolence; control of weight helps reduce the

severity.

Pulmonary Involvement

0023There are reports that sudden onset of severe chest

infection and/or pneumonia can result in death, ex-

tremely suddenly, at any age.

Diagnosis

Clinical Diagnosis

0024Clinical diagnosis criteria were agreed in the early

1990s, and continue to be revised (Table 2).

tbl0002Table 2 Clinical diagnostic criteria

Major criteria: awarded 1 point each

. Hypogonadism; genital hypoplasia; pubertal deficiency

. Infantile central hypotonia

. Infant feeding problems – failure to thrive

. Rapid weight gain between the age of 1 and 5

. Characteristic facial features

. Developmental delay/mental retardation

Minor criteria: awarded ½ point each

. Small hands and feet for height and age

. Narrow hands with straight ulnar border

. Hypopigmentation

. Myopia, esotropia

. Thick, sticky saliva

. Typical behavior problems

. Skin-picking

. Decreased fetal movement and infantile lethargy

. Short stature compared with family at age 15

. Sleep disturbances/apnea

. Speech articulation defects

Supportive criteria

: no points

. Temperature control problems

. Unusual skill with jigsaw puzzles

. Scoliosis/kyphosis

. High pain threshold

. Decreased vomiting

. Early adrenarche

. Normal neuromuscular studies

. High pain threshold

Diagnosis should be strongly suspected:

. In those under 3 years of age with five points, three of which

must be from major criteria

. In those over 3 years of age with eight points, four of which

must be from major criteria

Some clinicians consider more emphasis should be given to some of

these.

Smith A, Haan E, Warne G et al. (1998) Prader–Willi syndrome: a new

study of the Australian Paediatric Surveillance Unit. Journal of Paediatric

Child Health 34(4): 398–399 require for those:

under 3 years of age, three major and two minor findings

7over 3 years of age, four major and six minor criteria.

DEVELOPMENTAL DISABILITIES AND NUTRITIONAL ASPECTS/Prader–Willi Syndrome 1767

Genetic Diagnosis

0025 Clinical diagnosis should be confirmed with genetic

studies. PWS is caused by the absence of normally

expressed genes on the paternally derived chromo-

some 15, on the long arm (q11 – q13). The majority

with PWS – approximately 70% – have a deletion

observed during fluorescence in situ hybridiza-

tion (FISH). Some 29% have maternal uniparental

disomy (UPD), confirmed by molecular studies. The

remaining 1% have neither deletion nor disomy but

an abnormality in the imprinting center in q11–q13.

About 5% with deletion or disomy have a transloca-

tion or other structural abnormality causing the ab-

normality in the Prader–Willi critical region (PWCR).

Clinical Differences

0026 Differences are emerging between those with deletion

and disomy PWS. However, many early findings are

still subjective both in reporting and interpretation.

Some of these currently indicate that birth weights

seem to be lower in those with deletion, and that a

shorter time for tube feeding is needed amongst

those with UPD, possibly reflecting a lesser degree

of hypotonia.

0027 African-Americans are less likely to have small

hands and feet.

Nutritional Management

0028 Early appropriate intervention is essential. Sadly,

many individuals still do not receive correct nutri-

tional and dietary management at an early stage.

0029 Whenever a diagnosis is confirmed (or even sus-

pected), dietary treatment should commence.

0030 Poor feeding leading to failure to thrive and hyper-

phagia leading to rapid onset of weight are the com-

plete antithesis. Yet in individuals with PWS, both are

present at different stages of development; nutritional

management must therefore encompass these two

extremes.

0031 PWS is clearly an eating, and not simply a weight,

disorder. It is the most common example of genetic

obesity secondary to an impaired satiety response,

and must neither be confused nor compared with

bulimia nervosa in causality or treatment.

Phase 1

0032 Neonates have a decreased suck, thus breast-feeding

is rarely successful. Special methods of feeding, e.g.,

nasogastric tube feeding, are required almost without

exception. Some mothers choose to express breast

milk; others find this option impossible to maintain

and may therefore need reassurance that infant for-

mula is acceptable.

0033Transition from tube- to bottle-feeding should not be

delayed longer than necessary, but an adequate oral

intake is essential before finally removing the tube.

0034Milk delivery at the right pace is essential; atten-

tion should center on three reflexes: lip closure,

sucking, and swallowing. In addition to diminished

suck, poor head and neck control is common – due

to hypotonia – and exacerbates the difficulties en-

countered during feeding. Advice about positioning

the infant is important. Small frequent feeds are

advisable.

0035Infants with PWS rarely wake for feeds and are

normally unresponsive to both their own needs and

their surroundings.

Alternative Bottles and Teats

0036Use of a special bottle, e.g. Haberman, Chicco, Mead

Johnson Soft, has been found to be invaluable for

many parents and infants, although professional

opinion as to their suitability is divided. Thus, caution

when recommending these is needed. Special teats,

supplied with the above bottles, or lamb’s or ortho-

dontic types fitting normal feeding bottles may also

aid feeding, although it must be noted again that

professional opinion as to their advisability is

divided.

0037Provided a safe swallow is present, feeding systems

with a soft spout may be suitable.

Cup Feeding

0038Not only does this method fit with the baby-friendly

hospital initiative, but it is recommended for use

with sick and low-birth-weight infants by the World

Health Organization and UNICEF.

Spoon-Feeding

0039Sometimes it may be preferable to give liquids from

a spoon.

Supplements

0040It may be necessary to increase the energy density of

the feed to insure an adequate energy level is taken.

Alterations to feed concentration must always be

done under the supervision of a professional, e.g.

dietitian or health visitor.

0041Thickening feeds may help and there are several

commercial products available. Again, this should

never be done without professional supervision.

0042Advice relating to vitamin and mineral supple-

ments needs to be given on an individual basis.

Weaning

0043Introduction of solids may commence around 4

months; parents/carers may need reminding of the

1768 DEVELOPMENTAL DISABILITIES AND NUTRITIONAL ASPECTS/Prader–Willi Syndrome

risks of commencing solids too early, particularly as

infants with PWS often take solids from a spoon

better than liquid from a bottle. Introduction of solids

not only introduces the infant to new foods and tastes

and textures, but assists with mouth muscle develop-

ment, which is necessary for later speech develop-

ment. Without good feeding skills it is unlikely that

good articulation skills will be present.

0044 Signs of poor feeding within this population are

subtle and are summarized in Table 3.

Fluids

0045 Fluid intake may continue to be compromised in

toddlers and young children, so particular attention

to insure an adequate intake is essential. Thickening

of fluids may need to be continued.

0046 Sugars and other concentrated carbohydrate, e.g.,

honey and sweetened baby drinks should be avoided

both to lessen the risk of a ‘sweet tooth’ or dental

caries developing, and to limit energy intake.

Energy Intake

0047 Carers (normally parents) are usually delighted when

the infant develops an appetite and takes food easily.

At this stage of development, energy intake needs to

be adequate but not excessive; comprehensive nutri-

tional assessment by a qualified professional (usually

a dietitian) who understands the syndrome is neces-

sary to insure appropriate intakes.

0048 However, it is not uncommon for parents to con-

tribute unwittingly to the failure to thrive – they are

so anxious to prevent overweight or obesity, they

actually ‘starve’ the child, who fails to gain weight

or achieve expected linear (height) growth. Theoret-

ical needs must be matched by actual intakes. As

weight gain can be extremely rapid – there are reports

of excess fat deposits preceding the increase in appe-

tite – achieving the right balance is not easy.

0049Weight should be recorded regularly, at a minimum

monthly, but in infants under 12 months, weekly

weighing is recommended. Length/height measure-

ments are necessary. Results should be plotted on

standard height/weight or body mass index charts –

developmental records quickly show any deviation

from normal patterns of growth. Linear growth

should continue on the same centile, even though this

is well below the average; weight should continue

along the same centile and not be allowed to become

more than two centiles higher than the height one.

PWS-specific growth charts have been devloped in

some countries.

Energy Requirements

0050An appreciation of the abnormal body composition is

essential; this provides a partial explanation of the

need for a lower energy intake. Observations indicate

that, while normal children grow on 11–14 kcal

(46–59 kj) cm

1

height, those with PWS require only

10–11 kcal (42–59 kj) cm

1

height. To achieve weight

loss, levels of 7–8 kcal (29–33 kj) cm

1

height may be

needed.

Phase 2

0051To follow any dietary regime is difficult. Adhering to

a strict regime for life is particularly restrictive. For

people with PWS not only is an energy-controlled diet

necessary, but it is made even more difficult because

of the inherent lack of satiety. Teenagers with the

syndrome do not exhibit the normal pubertal growth

spurt.

0052Obsessions around food further compromise suc-

cessful management. Such obsessions with food must

never be underestimated and may include:

0053needing to know what is for lunch and supper at

breakfast time

0054creative play revolving around making meals

0055collecting recipes and pictures of food

0056wanting to watch every food and cookery program

on TV

Nevertheless, children can be taught, for example:

what is/is not acceptable

0057e.g. quantities of food consumed at mealtimes

0058what is a ‘good’ food and what should be avoided

because of a high energy density

0059normal social behavior, e.g., it is OK to want some-

thing to eat late afternoon but not immediately

after lunch

0060to eat slowly, replacing cutlery on the plate

between each mouthful and not gorging

tbl0003 Table 3 Signs of poor feeding

. Poor weight gain in infancy

. Slow intake

. Excessive time spent feeding the child

. Multiple swallows to clear mouth

. Irritability during feeding

. Frequent respiratory infections

. Excessive wet burps

. Excessive drooling

. Family fatigue from special food preparation

. Coughing while swallowing

. Difficulty in moving to new textures so food needs thickening

. Delay in accepting new textures, e.g., more lumps

. Chronic constipation

. Excessive weight gain – due to limited variety of foods

because of inability to accept new textures

Adapted from Morris M (1993) Feeding the young child with PWS. The

Gathered View XVIII(1): 6–7.

DEVELOPMENTAL DISABILITIES AND NUTRITIONAL ASPECTS/Prader–Willi Syndrome 1769

Unsurprisingly, there is no single successful diet. The

one that should be followed is that which is accept-

able to client and carer, fits in with the family (resi-

dential or group home) eating pattern, and provides

all macro- and micronutrients at the right energy

level to maintain growth and/or weight. The current

emphasis amongst professionals for ‘healthy eating’

regimes at an unspecified energy level is unhelpful to

both those with PWS and parents/carers supporting

them, because of the satiety problems.

0061 It is possible for older people with PWS to lose

weight and return to an acceptable agreed level, pro-

vided they are in a suitable environment with under-

standing and sympathetic support. A body mass

index of 30 is an achievable and realistic goal for

adults.

0062 As weight reduces, mobility increases; increased

self-esteem must not be undervalued.

Fluids

0063 Fluid intake needs to be at the right level. Water soft-

eners, which exchange calcium with sodium salts,

must never be used with infants and young children

as high sodium intakes would be dangerous. Caution

must be observed with artificially sweetened drinks to

insure acceptable daily intake levels of such sweeten-

ers are not exceeded.

0064 Water intoxication has been reported (although

only as a side-effect or in conjunction with medica-

tion), resulting in coma. Thus, statements such as ‘you

can drink as much as you like’ need to be tempered,

e.g., up to 1 liters diluted low-energy squash.

Contributory Factors

0065 Successful management of PWS is not restricted to

nutritional considerations.

Accessibility of Food

0066 Food-seeking and stealing are peculiar phenomena,

hard for the uninitiated to accept, and difficult char-

acteristics to manage. Environmental controls are

frequently essential, e.g., locking food cupboards,

refrigerators, and freezers. Other measures, which

conflict with normally acceptable social behavior,

are often needed. These may include restricting access

to money (and shops) and insuring no food is access-

ible, e.g., in a fruit bowl or in another family

member’s (or resident’s) bedroom.

0067 Some individuals will steal and consume any

food they find, including some normally not eaten

by humans (pica), e.g., cat and dog food, berries

and other garden produce, frozen products, discarded

food scraps in dustbins.

0068Research indicates that denial of food-stealing and

consumption is related to cognitive learning problems

and is not deliberate deception. Strategies for dealing

with such events must be known to all concerned and

without exception followed – inconsistency compli-

cates management and confuses the individual. A

written contract is helpful.

Special Occasions, Holidays, and Treats

0069People with PWS should be included in social activ-

ities, although the importance of planning ahead and

providing the necessary supervision should never be

underestimated. The preferable approach is to reduce

overall energy intake prior to such events rather than

afterwards.

0070People with PWS can have as rough a day as

anyone else and may benefit from an occasional

extra treat.

Reinforcers or Tokens

0071People with PWS respond well to programs that allow

collection of points towards a predefined reward, or

as a reinforcer. Alternatives to foods are preferable,

e.g., books, games, toiletries, make-up; some people

with PWS respond well to an additional period of

attention and time.

Rules and Routine

0072Consistency in both these is essential – individuals do

not respond well to alterations to routine or inconsist-

ency in overall care.

0073Occasionally rules have to be made which affect

others, e.g., eating only at mealtimes. Any manage-

ment program must insure all involved in care, both

direct and indirect – family, friends, teachers, social

workers, neighbors, welfare assistants, club organ-

izers – realize the importance of decisions and adhere

to them.

Exercise

0074Parents can assist with improving muscle develop-

ment from a very early age. The individual program

may be devised by a physiotherapist or be adapted

from a scheme such as Portage, which is a programme

of exercises to assist the development of handicapped

babies and young children. All those with PWS, not

only children, must be encouraged to participate in

physical exercise daily to assist both with improving

muscle tone and increasing body metabolism.

0075The beneficial effects of growth hormone treat-

ment, both increasing muscle mass and improving

muscle tome, makes physical activity easier. Increased

activity in turn allows a higher energy intake to be

consumed.

1770 DEVELOPMENTAL DISABILITIES AND NUTRITIONAL ASPECTS/Prader–Willi Syndrome

Education

0076 Many children commence at a mainstream infant

school, progressing to a similar junior/primary school.

It is acknowledged that the pace of learning falls off

from about the age of 8 years, after which time most

children, though not all, have difficulties in keeping

up with their peers. Few individuals complete educa-

tion without additional support (welfare assistants or

extra individual teaching) in a mainstream setting. A

move to a different school, e.g., for those with mild or

moderate learning difficulties, may be the better

option. Others may require specialist help for other

developmental difficulties, e.g., physical handicap or

speech delay, and this is best found in specialist

schools.

0077 The need to restrict access to food makes adult

vocational training difficult but not impossible.

Many young adults have false expectations – some

of which educators have encouraged, through ignor-

ance rather than intent – which can rarely be met.

Failure results and is frequently accompanied by a

rapid and unacceptable weight gain. Yet in the right

environment people with PWS have achieved success

with qualifications in academic, craft, or practical

subjects. Many are extremely good with young chil-

dren and the elderly, provided appropriate super-

vision is in place.

Behavioral Management

0078 Frequent references have been made to behavior

management programs. Each must have individual

needs assessed by the appropriate professionals who

then devise a sustainable program. The importance

of regular reviews, including dietary management,

cannot be overstated.

Residential Options and Independence

0079 Adults with the syndrome may give the impression

of being eminently capable of both looking after

themselves and making appropriate decisions. This

frequently leads to inappropriate or inadequate sup-

port. Professionals have a duty to plan suitable care in

a safe environment. This may be a group home – the

Prader–Willi Syndrome Association (USA) led the

field in developing PWS-specific homes – a concept

gathering momentum in other countries in Europe

and Australia. A care village or community, hostel,

or sheltered housing may suit some adults better.

0080 Each residential environment must be considered on

its own merits as to whether it can handle the multifari-

ous problems of PWS, alongside other residents, and

whether it is suitable for the particular individual.

0081 Placements which break down are generally

those where proper insight into the complexities of

the syndrome are lacking, by frequently dismissing,

through disbelief, these management and support

issues.

0082Realistic expectations are essential and no carer

should have guilt feelings about restricting access to

food.

Support Groups

0083There are, at the time of writing (early 2002) support

groups for parents and professionals in 41 countries.

An international body – International Prader–Willi

Syndrome Organization (IPWSO) – was constituted

in 1991 and each of the 25 constituent countries has

both a parent and professional delegate. International

conferences are arranged every 3 – 4 years, when sci-

entists, professionals, carers, parents, and those with

PWS are brought together for lectures, seminars, and

workshops.

See also: Diabetes Mellitus: Etiology; Growth and

Development; Obesity: Etiology and Diagnosis;

Osteoporosis; Peptides

Further Reading

DeBelder AN (1992) Dextran. In: Whistler RL and BeMiller

JN (eds) Industrial Gums, pp. 399–425. New York:

Academic Press.

DEXTRINS

J N BeMiller, Purdue University, West Lafayette,

IN, USA

Background

0001 Dextrin is a generic term applied to a variety of

products obtained by heating a starch in the presence

of small amounts of moisture and an acid. Dextrins

can be made from any starch and are generally classi-

fied as white dextrins, yellow (or canary) dextrins,

and British gums. Each is more water-soluble and

produces less viscous solutions or dispersions than

its parent starch. Each is produced by combinations

of slight depolymerization (hydrolysis) and transgly-

cosylation (molecular rearrangement). Transglyco-

sylation produces more highly branched structures

and forms glycosidic linkages not found in native

starches. Most dextrins are used as adhesives for

paper products. Only white dextrins and only small

amounts of them are used in prepared foods. White

dextrins are prepared by heating a dried, acidified

starch.

0002 Other hydrolytic breakdown products from starch

are characterized by their dextrose equivalency (DE),

which is the percent of reducing power compared to

anhydrous d-glucose (dextrose). The DE value is in-

versely related to molecular weight, i.e., the degree of

polymerization (DP), and is, therefore, an indicator of

the degree of hydrolysis. (The DE value of anhydrous

d-glucose is 100. The DE value of native starch is 0.)

When all products of starch hydrolysis were made

by treatment of starch with acid, the properties of

a product were largely a function of DE. Now with

a variety of treatments and processes being used, two

products with equivalent DE values (average degree

of polymerization) can have rather different proper-

ties because of different distributions of molecular

sizes.

0003 Maltodextrins are those products having DE values

of less than 20, generally DE 5–19. Syrup solids

are those products of starch hydrolysis with DE

values of more than 20 that are available as dry

powders; in other words, they are dried low-DE

glucose syrups.

0004While dextrins are little used in foods; maltodex-

trins and syrup solids are used extensively. Both are

produced from starch by hydrolysis only, i.e., without

molecular rearrangement, and are of lower average

molecular weight than either dextrins or acid-thinned

(thin-boiling) starches, the latter being slightly

depolymerized starches that remain in granular

form. The primary difference between thin-boiling

starches, maltodextrins, and syrups/syrup solids is

the degree of depolymerization. The primary differ-

ence between dextrins and thin-boiling starches is the

method of preparation.

Production

0005Dextrins are prepared by heating a starch moistened

with dilute hydrochloric acid or heating a moist

starch in the presence of gaseous hydrogen chloride

until a cold-water-soluble product is formed.

0006Maltodextrins and syrup solids are prepared in

basically the same way as are starch-based glucose

syrups, except that the process is stopped at an earlier

stage to keep the DE value low. Depolymerization of

a starch can be effected with either an acid or an

enzyme(s) or by combination treatments. These pro-

cesses are referred to as acid conversions, enzyme

conversions, and combination conversions, respect-

ively. Conversions to produce maltodextrins are usu-

ally done in a continuous process. In a typical process,

a starch slurry (30–40% dry solids, 17–22 Be

)atpH

6.0–6.5 is pasted, generally in a jet cooker (*105



C),

followed by an atmospheric flash. Conversion (lique-

faction) is accomplished with a thermostable bacter-

ial a-amylase at 95–100



C. Depolymerization is

stopped after 60–120 min by enzyme inactivation,

and the pH is adjusted. The solution is filtered,

treated with carbon, concentrated, and spray-dried

to give a maltodextrin or syrup solid preparation. In

DEXTRINS 1773

a lower-temperature batch process, steam is intro-

duced into a starch slurry for pasting, which is ac-

complished at 80–90



C. Otherwise the processes are

identical, except that a debranching enzyme may be

used in the batch process. (See Enzymes: Functions

and Characteristics.)

0007 For an acid conversion, a starch is acidified with a

food-grade acid, generally to a pH value of about 2.

Hydrochloric acid is preferred because of a preference

for sodium chloride in the final product. The slurry is

passed through a jet cooker to paste the starch and

then through a converter to depolymerize it. Alterna-

tively, the starch can be pasted, the pH adjusted after

pasting, and the conversion done in a batch process.

The degree of hydrolysis, i.e., the DE value, is con-

trolled by a combination of time, temperature, and

acid concentration. The process is terminated via

cooling and neutralization. The resulting liquor is

clarified, treated with carbon, concentrated, and

spray-dried.

0008 A variety of maltodextrins can be produced. The

variables in the process are the starch source, the

means of conversion (including the specificities of

enzymes used), and the extent of breakdown (i.e.,

the DE value of the product). In general, DE values

range from 5 to 19; the amount of d-glucose (dex-

trose) ranges from 0.5 to 3%; and the moisture level is

4–6% (Table 1). As much as 98% of the components

can be of DP 3 or higher.

Properties

0009 Dextrins are cold-water-soluble. Upon drying of a

dextrin solution, clear films are obtained. Malto-

dextrins are generally even more soluble, although

special crystalline and less soluble types are produced.

Depending on the type, 15–60% solutions can gener-

ally be made easily at room temperature. Syrup solids

are slightly sweet, hygroscopic, semicrystalline, or

powdery amorphous products. Maltodextrins are

less hygroscopic because of their lower monosacchar-

ide content. They are available as spray-dried powders

and in agglomerated and other forms, all of which are

essentially white, free-flowing powders. They have

the ability to absorb flavor oils and other nonaqueous

liquids. Their flowability, compressibility, and low

hygroscopicity make them excellent excipients. They

provide good to excellent solution clarity. They pro-

vide moderate to very low solution viscosity, and low

to extremely low browning. They are generally bland,

and generally resist caking. They form protective

films with oxygen-barrier properties and provide

binding, surface sheen, and high solids content with-

out affecting freezing points. Characteristics and

properties that increase as DE increases are bulk

density, hygroscopicity, ability to participate in Mail-

lard-type browning reactions, solubility, clarity of

solutions, osmolality, freezing-point depression,

sweetness, and particle size. Characteristics and prop-

erties that decrease as DE increases are abilities to

form a film, build viscosity, serve as a binder, and

provide body.

0010Typical properties of typical maltodextrins with

average DE values of about 5 are formation of clear

solutions at concentrations up to 15% at room tem-

perature, production of significant viscosity at 20–

40% concentration, very minimal hygroscopicity and

sweetness, and excellent film-forming characteristics.

Typical properties of typical maltodextrins with

average DE values of about 10 are formation of

clear solutions at concentrations up to 30% at room

temperature, very low hygroscopicity, and low sweet-

ness and ability to effect browning. Typical properties

of typical maltodextrins with average DE values of

about 15 are formation of clear solutions at concen-

trations up to 50% at room temperature, slight sweet-

ness, and low hygroscopicity and ability to effect

browning. (See Browning: Nonenzymatic.)

0011Especially prepared, low-DE, more crystalline

maltodextrins produce a fatty mouthful. They are

most often made from potato or tapioca starch; oat

flour and bran is another source; rice flour has also

been used for their preparation. These products,

when hydrated, form soft, spoonable gels with a

creamy texture. They generally have DE values less

than 3.

Food Uses

0012Dextrins are usually used to produce protective coat-

ings such as those applied to panned confections.

Maltodextrins are used in a wide spectrum of

food products, including baby foods, bakery prod-

ucts, beverages, breakfast cereals, canned fruit

tbl0001 Table 1 Typical analysis of a maltodextrin product

Carbohydrate 94.5

Moisture 5

Protein <0.1

Fat <0.1

Crude fiber <0.1

Sodium <0.1

Calcium <0.03

Phosphorus <0.03

Magnesium <0.01

Potassium <0.005

Sulfite <0.001

Iron <0.00025

Zinc <0.0001

1774 DEXTRINS

products, condiments, confections, dairy products,

desserts, dietetic and nutritional beverages, frozen

meals, infant formulas, jams, jellies, margarines,

meat products, dry mixes of all kinds, peanut butter,

pet foods, preserves, sauces, snack foods, soups, and

syrups. Applications are divided approximately as

follows: as carriers for spray-dried and extruded

flavors (20–25% of total market), as bulking agents

for flavoring materials and high-intensity sweeteners

(20–25%), as fat sparers and replacers (20–25%), in

nutritional beverages (15–20%), and in confections

and coatings (5–15%). Properties that make them

useful in these applications are low hygroscopicity

(prevention of caking) while being easily dispersible

and readily soluble, generally bland taste, encapsu-

lation of essential oils and other flavors (ability to act

as a carrier), film formation (ability to coat), binding

action (adhesiveness), provision of lubricity, control

of expansion of extruded products, provision of

bulking, and texture creation. They prevent sugar

crystallization and improve chewiness in soft confec-

tions, increase shelf-life and maintain moisture levels

in hard confections, and speed up the panning pro-

cess. They are effective binders and excipients for

direct compression confections (and pharmaceutical

tablets). They control the freezing point and ice crys-

tal growth in frozen dairy products. They control

sugar crystallization and sweetness and add solids to

bakery fillings, frostings, and glazes. They provide a

chewy texture and extend the shelf-life of fruit

leathers and granola bars. Maltodextrins are

generally excellent spray-drying aids and are used

for agglomeration of food gums. Partially crystalline

maltodextrins are effective fat sparers and replacers

in low-fat or nonfat dairy products. All maltodex-

trins are digestible, having an energy value of

about 3.8 kcal g

1

.(See Cereals: Breakfast Cereals;

Dietetics; Fat Substitutes: Use of Fat-replaced Foods

in Reducing Fat and Energy Intake; Infant Foods:

Milk Formulas; Infants: Nutritional Requirements;

Low-fat Foods: Types and Manufacture; Low-fat

Spreads.)

0013 Syrup solids are generally used alone or in combin-

ation with maltodextrins when one or more of the

following characteristics are desired: browning, freez-

ing-point depression, greater solids content, increased

solubility, some sweetness, increased clarity.

Digestion and Metabolism

0014All products made by simple depolymerization of a

starch (food dextrins, thin-boiling starches, malto-

dextrins, dried syrups, syrups) are nutritive sacchar-

ides. They are generally recognized as being safe and

nontoxic. Human digestive enzymes (pancreatic a-

amylases and maltooligosaccharidases of the epithe-

lium of the small intestine) convert each product into

d-glucose, which is absorbed, raising blood sugar

levels. The d-glucose is then metabolized, so each of

these products provides approximately 3.8 kcal g

1

Maltodextrins and syrup solids are the carbohydrates

of choice for sports drinks and liquid diet formula-

tions because of the low osmolality of their solutions.

These properties and their easy digestibility also make

them suitable for infant formulas. (See Carbohy-

drates: Digestion, Absorption, and Metabolism.)

See also: Browning: Nonenzymatic; Carbohydrates:

Digestion, Absorption, and Metabolism; Cereals:

Breakfast Cereals; Dietetics; Enzymes: Functions and

Characteristics; Fat Substitutes: Use of Fat-replaced

Foods in Reducing Fat and Energy Intake; Infant Foods:

Milk Formulas; Infants: Nutritional Requirements; Low-

fat Foods: Types and Manufacture; Low-fat Spreads;

Starch: Structure, Properties, and Determination