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is a sensitive tool. However, the method is costly and

time-consuming. To prevent or minimize changes in

structure of ice cream during preparation for scan-

ning electron microscopy, samples are frozen and

fractured in liquid nitrogen. They are then freeze-

dried and coated with a 3.0-nm-thick layer of plat-

inum while under a high vacuum. Confocal scanning

microscopy has the advantage of permitting examin-

ation of the ice cream in the native state. The instru-

ment scans thin parallel layers of a sample and

develops a three-dimensional image from the data.

Laser diffraction spectroscopy is reliable for measur-

ing fat globule size distributions in ice cream. Images

obtained by microscopy can be transferred to a

microcomputer for analysis. The extent of destabil-

ization of the fat in ice cream can be estimated by

comparing the absorbance of diluted samples of both

melted ice cream and the mix from which the ice

cream was made.

0028 Other approaches to determining the physical char-

acteristics of ice cream mixes include: (1) measuring

the electrical charge on the fat globules by observing

their electrophoretic mobilities in charged fields;

(2) measuring mix viscosities over a wide range of

shear and calculating the mean diameter of the fat

globules from the data; and (3) determining the

stability of the emulsion of fat by observing the rate

of coalescence of fat globules.

Microbiological Properties

0029 Although ice cream is not a sterile product, it contains

no harmful microorganisms when it is produced by an

approved process and under hygienic conditions.

Furthermore, freezing destroys many bacteria, and the

frozen condition of the product prevents growth of

microorganisms. Except for a large outbreak of sal-

monellosis (see below), few cases of food-borne illness

have been traced to commercially manufactured ice

cream. Sporadic cases of salmonellosis have been

traced to home-produced ice cream, especially that

containing raw eggs. (See Salmonella: Salmonellosis.)

0030 Most regulatory agencies require that ice cream

mixes be pasteurized. Additionally, they exercise con-

trols over manufacturers to see that mixes receive an

adequate heat treatment and that hygienic practices

are followed throughout the processing plant.

0031 The primary area of concern about microorgan-

isms in frozen desserts is contamination of the frozen

product during the addition of fruits, nuts, and fla-

vorings, as well as during filling of containers. The

microorganisms that present significant risk are Lis-

teria monocytogenes and Salmonella.

0032 Although illnesses are rarely, if ever, traced to

L. monocytogenes in frozen desserts, there have been

numerous recalls of frozen desserts found to contain

these bacteria. Presently, in many countries detection

of any L. monocytogenes in ready-to-eat foods is

reason for recall by the processor. Infants and persons

with low immunity are susceptible to infections by

L. monocytogenes, whereas the normal healthy adult

tolerates them well. They are widely distributed in the

environment, including plants and animals, and are

capable of living in moist, cool places. Unlike most

pathogenic bacteria, L. monocytogenes grows at tem-

peratures as low as 3



C. These factors raise the prob-

ability of contamination of frozen desserts from the

environment by L. monocytogenes compared with

other foodborne pathogens. A 1989 survey of 530

samples of ice cream mix (85), ice cream (394), and

ice cream novelties (51) by Health and Welfare

Canada revealed only two samples that contained

L. monocytogenes. The Working Group of the

World Health Organization found that the incidence

of L. monocytogenes in frozen desserts varied from

0 to 5.5% and that the number of colony-forming

units was usually less than 15 per gram of sample.

0033Salmonella cells are easily killed by pasteurization,

but their frequent presence in raw milk and eggs

means that all frozen dessert mixes containing these

ingredients should be treated to destroy the organism.

The multistate outbreak of salmonellosis from ice

cream that occurred in the USA during 1994 was

believed to have been caused by the transport of

pasteurized ice cream mix in tanks of trucks in

which liquid raw eggs had been hauled. Apparently,

the tanks that were used had been inadequately

cleaned and sanitized prior to receiving the ice

cream mix. The mix was not repasteurized prior to

freezing at the plant to which it was delivered.

0034Microbiological analyses routinely done with frozen

dairy desserts are the aerobic plate count (APC), also

called the standard plate count, and the coliform count

(CC) or the Enterobacteriaceae count. Standards are

commonly set at 20 000 g

1

for the APC and 10 g

1

for

the CC. Whereas the APC method reveals numbers of

most of the bacteria capable of growing in an atmos-

phere of air and at moderate temperatures of about



C, the CC method selects for Gram-negative, facul-

tatively anaerobic bacteria capable of fermenting

lactose and of growing in the presence of certain dyes

and bile. The enterobacteria include the coliform

bacteria plus other similar Gram-negative bacteria

that are able to ferment glucose.

0035Counts can be made of culture bacteria in frozen

yogurt by using a medium that is both selective and

differential in function and incubating the plates at



C in an atmosphere of CO

. On modified Elliker’s

lactic agar colonies of Streptococcus thermophilus

appear small and red, whereas those of Lactobacillus

3230 ICE CREAM/Properties and Analysis

bulgaricus appear large and white. (See Lactic Acid

Bacteria.)

Sensory Properties

0036 Ice cream has many attributes that make it a favored

food of most people. Among these are a rich sweet

flavor, a smooth and resistant texture, and a cold

sensation that contrasts with the warmth of most

other foods. The chemical and physical properties

imparted by the ingredients and the processes used

in manufacture and handling largely determine the

sensory properties.

0037 The human senses most used in evaluating ice

cream are taste, smell, touch (feel), and sight. Only

infrequently does a frozen dessert affect hearing. Al-

though it may seem strange that smell is involved with

a frozen food, it is only by smell that humans can

detect flavors other than sour, bitter, salty, and sweet.

These four flavors are detected by taste buds on the

tongue, whereas odors are sensed in the back of the

mouth and in the nasal cavity. Substances detected by

smell are volatile, and the warmer the food, the higher

the degree of volatility of these substances. Therefore,

for the most flavors to be sensed, a frozen dessert

should be consumed at as high a temperature as prac-

ticable, and it should be eaten slowly so it does not

cool the mouth excessively. (See Sensory Evaluation:

Practical Considerations.)

0038 Since physical abilities vary among individuals, as

do preferences for various attributes, it is necessary to

select the proper sensory analysts and to insure that

they meet the requirements imposed by the purpose of

the analysis. Whereas trained analysts are needed to

describe sensory attributes and to determine whether

products meet specifications, untrained analysts are

desired to determine acceptability to the public.

0039 High-quality unflavored ice cream tastes sweet,

heated (cooked), nutty, and creamy or buttery.

Depending on the type and amount of flavoring

added, all of these flavors except sweet may become

imperceptible except to the expert evaluator. Mild

flavors like vanilla tend to mask little of the back-

ground flavor, whereas chocolate masks other flavors

well. The task of the ice cream formulator is to de-

scribe a mix that will provide the balance of ingredi-

ents that will give consumers a product with the most

desirable flavor, texture, color, appearance, and keep-

ing quality at a price that is acceptable. The engineer

must provide a process that enhances, or at least does

not damage, these properties. The manufacturer must

insure that the ingredients are of high quality and that

the process is performed correctly. Unfortunately,

there are many factors that can affect the sensory

properties adversely.

0040The International Dairy Federation (IDF) has es-

tablished standards for evaluation of dairy products,

including ice cream (IDF standard 99C). This stand-

ard defines an expert assessor as a person ‘with a high

degree of sensory sensitivity and experience of sens-

ory methodology, who is able to make consistent and

repeated sensory assessments of various products.’ A

panel consists of ‘a group of expert assessors.’

0041The standard gives instruction on the sampling and

preparation of samples; the test room; recruitment,

selection, training, and monitoring of assessors; re-

quirements for a panel; supervision; documents and

equipment; and assessment. Furthermore, a scale is

recommended that rates each chosen attribute in re-

lation to the preestablished sensory specification as

follows: 5, conforms; 4, deviates minimally; 3, devi-

ates noticeably; 2, deviates considerably; 1, deviates

very considerably, and 0, unfit for human consump-

tion. Descriptions of the deviations should be given

for samples scoring 1, 2, or 3. Furthermore, when

scores of individual assessors fail to agree within

one point, rescoring of the attribute is required. The

mean value of the final score is then recorded. Terms

used to describe sensory attributes should be listed in

the order of most to least significance for the quality

of the product.

0042Samples within a type should be examined in

random order and presented so analysts do not

know the identity. Products with a mild flavor and

low fat content should be examined ahead of those

with strong flavors and/or high fat content. Prior to

assessment, samples should be tempered from their

storage temperature of 18



C or below to 13



+ 2



0043For calibration, at least one negative and one posi-

tive sample should be presented to the analysts who

should discuss them prior to assessment. These

samples should be available during the assessment

session, but there should be no intercommunication

among analysts during this time.

0044Appearance is evaluated by observing the cut

surface of the frozen sample. Texture and body are

determined by cutting the sample with a spoon then

chewing it and letting it melt in the mouth. Flavor and

odor are observed as the sample melts in the mouth.

Melting quality is assessed by observing samples of

equal size and temperature as they melt in flat dishes

at 22 + 2



Defects in the flavor of ice cream

0045These defects result from an improper balance of

ingredients, the use of ingredients of poor quality,

or improper processing or storage. Defective dairy

ingredients can impart the following off-flavors:

sour (acid), stale (oxidized), rancid (lipolyzed),

ICE CREAM/Properties and Analysis 3231

lacking freshness, or unclean. The amounts of sweet-

eners and flavorings used can be excessive or insuffi-

cient. Furthermore, flavorings can cause an unnatural

flavor when they fail to match the true flavoring. For

example, vanillin is the major component of vanilla

extract, but it fails to provide many other flavor notes

of vanilla extract. Additionally, some sweeteners,

such as corn syrup and aspartame, impart flavors

other than sweetness. Ice creams, especially the mildly

flavored types, tend to absorb off-flavors during

storage if not protected. Surfaces exposed to air

tend to dry and to become oxidized.

Defects in texture of ice cream

0046 Most consumers prefer ice cream that feels smooth

and moderately firm when eaten. Degree of smooth-

ness (opposite of coarseness) depends on the sizes of

the substances suspended in the disperse phase of the

product. These suspended substances are ice crystals,

fat globules, casein micelles, particles of other pro-

teins, and air cells. Particles that are 0.1–2 mmin

diameter impart creaminess to ice cream whereas

particles larger than about 3 mm cause a gritty texture.

Ice crystals in freshly frozen ice cream are generally

too small to be detected in the mouth, but they grow

during storage when minute ice crystals melt and the

water migrates to other crystals on to which it is

frozen. Fat globules provide a creamy mouth feel

but are usually too small to be detected individually.

However, when the churning action of the ice cream

freezer causes aggregation of too many of the emulsi-

fied fat globules, a slick and greasy mouth feel is

imparted. Casein micelles are too small to be sensed

individually, but collectively they add to firmness. Air

cells affect primarily the firmness of frozen desserts.

Too little air results in a heavy product, whereas too

much air results in fluffiness. When air cells are quite

large, smoothness is diminished.

0047 Texture is affected by the melting point of the

unfrozen dissolved phase of the frozen product. A

high concentration of dissolved substances results in

a low freezing point, a relatively small amount of ice

crystals formed, and soft ice cream. Conversely, a low

concentration of dissolved solids results in hard ice

cream. Stabilizers and emulsifiers affect texture. Sta-

bilizers bind water, reducing the amount available to

form ice crystals. Emulsifiers contribute to formation

of small air cells as well as moderate clumping of the

fat. When used in desired amounts, emulsifiers pro-

vide stability to the emulsion, dryness, and a slowed

rate of melting.

Defects in color and appearance

0048 Consumers expect the color of foods to be properly

distributed and suggestive of the flavor and freshness.

Colors that are dull, faded, or uncharacteristic of the

labeled flavor are defective. Inclusions, which are

usually fruit pieces, nuts, candies, or bakery products,

need to be abundant and evenly distributed. Syrups

and preserves that are pumped into the soft-frozen

dessert should be distributed evenly and with minimal

spreading of the column of variegate (swirl).

Defects in melting quality

0049Ice cream should melt to a smooth and uniform con-

sistency within about 20 min at room temperature.

The ice cream on cones or stick novelties should melt

relatively slowly to permit consumption in the frozen

state. However, adjusting an ice cream formula to

produce slow melt can cause slow release of delicate

flavors. Slow melting can result from overuse of sta-

bilizer gums, emulsifiers, and corn syrup solids. Prod-

ucts containing a high amount of air (high overrun) or

fat tend to melt slowly. Air cells act as an insulator.

Fat stabilizes foam structure. Treatments that

destabilize proteins cause the curdy and free whey

appearance of melted ice cream.

Methods of determining sensory quality

0050Three basic approaches are used to evaluate frozen

desserts for sensory quality. These are: (1) by trained

experts working alone or in small numbers; (2) by

trained panelists; or (3) by untrained consumers in

large numbers. Research into the effects of various

treatments on specific sensory properties of ice creams

usually requires use of trained panelists who employ

techniques such as descriptive analysis and free-

choice profiling. Development of new products com-

monly involves screening of several formulae by a few

experts followed by tests of a small number of pro-

spective products by large numbers of consumers. A

small panel of experts usually monitors the quality of

finished products.

0051Descriptive analysis involves selection of qualified

panelists, training these panelists and using them to

describe the product attributes. Training consists of

several sessions during which panelists, through

examination of the type of product to be evaluated

and related samples, produce a list of applicable de-

scriptive terms on which they have come to agree-

ment by discussion and consensus. Reference samples

are developed for each descriptor. Similarly, free-

choice profiling involves development of descriptors,

but each judge develops a personal list of terms. Pan-

elists then rate on a point scale the intensity of each of

the terms selected, with 1 ¼low and 9 ¼high inten-

sity. Results of these types of analysis are tested stat-

istically by analysis of variance and multivariate

analysis of variance. Maps of the attributes, as they

relate to treatments and to each other, can be drawn

3232 ICE CREAM/Properties and Analysis

by canonical variate analysis for descriptive analysis

or by general Procrustes analysis for free-choice

profiling.

0052 A useful technique for testing the time and intensity

of flavor release in a food is called time–intensity

evaluation. The technique can be applied in evaluat-

ing the effect of ingredients on the release of volatile

flavors such as vanilla and chocolate. In one applica-

tion to ice cream, it was determined that the higher

the amount of milk fat, the slower the release of

vanilla flavor.

0053 Experts who evaluate samples on an informal basis

commonly refer to score cards and scoring guides

such as those developed by the Committee on Dairy

Products Evaluation of the American Dairy Science

Association. The score card lists the defects most

often found in ice cream, and the scoring guide sug-

gests scores that reflect the seriousness of the respect-

ive defects. For example, a sample that has no

observed defects is given a flavor score of 10 and a

body and texture score of 5. A deduction of one point

is made for a minor defect of flavor, such as lacking

flavoring, or of texture, such as slightly coarse (icy).

Serious defects in flavor, such as oxidized, rancid, or

acid, merit lower scores of no more than 6. Color,

melting quality, and package are also scored on a

scale of 1–5.

0054 Consumer panelists are chosen to represent the

target market. Because they are untrained, numbers

of panelists should be more than 50 and preferably

100. Panelists may be asked to indicate preferences by

ranking a few samples, or they may indicate their

degree of liking on a numerical scale (called hedonic

evaluation). A typical scale consists of seven points

where 1 ¼dislike extremely, 2 ¼dislike moderately,

3 ¼dislike slightly, 4 ¼neither like nor dislike,

5 ¼like slightly, 6 ¼like moderately, and 7 ¼like ex-

tremely. Hedonic tests can be analyzed statistically

when sufficient panelists are used.

See also: Freezing: Principles; Ice Cream: Methods of

Manufacture; Dietary Importance; Microbiology; Lactose;

Listeria: Properties and Occurrence; Pasteurization:

Principles; Salmonella: Salmonellosis; Sensory

Evaluation: Appearance; Texture; Taste

Further Reading

Andreasen TG and Nielsen H (1998) Ice cream and aerated

desserts. (Revised by Christensen ES) In: Early R (ed.)

The Technology of Dairy Products, 2nd edn, pp. 301–

324. Gaithersburg, MD: Aspen Publishers.

Bodyfelt FW, Tobias J and Trout GM (1988) The Sensory

Evaluation of Dairy Products, pp. 166–226. New York:

Van Nostrand Reinhold.

Koxholt MMR, Eisenmann B and Hinrichs J (2001) Effect

of fat globule size on the meltdown of ice cream. Journal

of Dairy Science 84: 31–37.

Lawless HT and Heymann H (1996) Sensory Evaluation of

Food: Principles and Practices. New York: Chapman

and Hall.

Li Z, Marshall RT, Heymann H and Fernando L (1997)

Effect of milk fat on flavor perception of vanilla ice

cream. Journal of Dairy Science 80: 3133–3141.

Marshall RT (ed.) (1993) Standard Methods for the Exam-

ination of Dairy Products, 17th edn, pp. 304–306,

469–479, 487–492. Washington, DC: American Public

Health Association.

Marshall RT (1998) Ice cream and frozen yogurt. In: Marth

EH and Steele JL (eds) Applied Dairy Microbiology,

pp. 81–108. New York: Marcel Dekker.

Marshall RT and Arbuckle WS (1996) Ice Cream, 5th edn.

Gaithersburg, MD: Aspen Publishers.

Ogden LV (1993) Sensory evaluation of dairy products.

In: Yui YH (ed.) Dairy Science and Technology Hand-

book 1. Principles and Properties. New York: VCH

Publishers.

Pappas CP (1988) Comparative laws and regulations on

compositional requirements for ice-cream in the EEC.

British Food Journal 90: 250–254.

Prindiville EA, Marshall RT and Heymann H (1999) Effect

of milk fat on the sensory properties of chocolate ice

cream. Journal of Dairy Science 82: 1425–1432.

Stone H and Sidel JL (1993) Sensory Evaluation Practices.

New York: Academic Press.

Welty WM, Marshall RT, Gru

n IU and Ellersieck MR

(2001) Effects of milk fat, cocoa butter or selected fat

replacers on flavor volatiles of chocolate ice cream.

Journal of Dairy Science 84: 21–30.

Dietary Importance

M J Tait, Birds Eye Wall’s, Gloucester, UK

D J Finney and S K Narhan, Unilever Research

Laboratory, Sharnbrook, UK

This article is reproduced from Encyclopaedia of Food Science,

Energy Content

0001Ice cream is a much maligned product, frequently

being considered, at best, a ‘fun food’–unworthy of

serious consideration – and, at worst, a ‘junk’ food, or

even downright harmful! These perjorative state-

ments have dogged the industry virtually from its

inception.

0002In reality, ice cream is a relatively well-balanced,

wholesome, easily digestible, and delicious food. It is

ICE CREAM/Dietary Importance 3233

because ice cream is a nutritious element of the diet

that it is frequently used as a meal component for

hospital patients.

0003 The composition of ice cream varies according

to legislation and to the complexity of ice cream

products, e.g., ‘Cornetto’, fancy gateaux, etc. It is

therefore difficult to define precisely an average com-

position and energy content.

0004 Most reputable sources seem to agree on energy

values of between 180 and 210 kcal per 100 g. An

average portion of ice cream – which is measured by

volume, rather than weight – is taken to be between

100 and 125 ml (50–79 g), giving a calorie count of

roughly 100 kcal per portion. This calorie density is

modest in comparison with other desserts and confec-

tionery, and there is a good nutritional balance of

macronutrients.

Macronutrient Composition

0005 Classically, the major ingredients of ice cream are

milk solids, milk or vegetable fat, and a variety of

added carbohydrates. The macronutrient com-

position of a typical ice cream, according to Souci,

Fachmann, and Kraut, and that according to the

‘Euroglace’ proposal, are given in Table 1. In both

instances, the nutritional quality of the milk-derived

protein enhances its value. In comparison with

many other dairy-based products, ice cream offers a

more nutritionally balanced dietary contribution.

(See Carbohydrates: Requirements and Dietary

Importance; Fats: Requirements; Protein: Require-

ments.)

0006 Finally, ice cream, derived as it is from milk, can be

an important source of minerals, notably of calcium,

and especially for children.

Micronutrient Composition

0007 The vitamins, macrominerals, and microminerals

present in dairy ice cream are listed in Table 2.

Refer to individual nutrients.

Sources of Micronutrients

0008The total micronutrient composition of ice cream

varies with the amounts and types of ingredients

used in its manufacture. Because of this variation,

the data given are only approximate.

Water-soluble Vitamins

0009In ice cream, the concentration of water-soluble vita-

mins, such as vitamin C and vitamins of the B com-

plex, are similar to, or slightly higher than, those in

pasteurized milk. The concentrations of these vita-

mins in both dairy and nondairy ice creams are gen-

erally similar. Ice cream is rich in vitamins B

and B

a 100-g portion supplies 20 and 14% of the US rec-

ommended dietary allowance (RDA) respectively.

Fat-soluble Vitamins

0010The type and concentration of fat-soluble vitamins in

ice cream depend on the type and level of fat used. A

100-g portion of dairy ice cream provides 11% of the

US RDA of vitamin A.

Minerals

0011The minerals found in ice cream are similar to those in

milk (Table 2). The one mineral that is clearly abun-

dant in ice cream, and which would contribute over

10% of the US RDA if 100 g of ice cream were

consumed, is calcium.

Effect of Storage on Micronutrients

0012Very few studies have been conducted on micronu-

trient losses in ice cream during storage at constant

temperatures and at fluctuating temperatures. Freez-

ing is generally regarded as the best method of preser-

vation when judged on the basis of retention of

nutrients. Substantial losses in micronutrient content

during the storage of ice cream are unlikely.

Health and Nutritional Issues

0013As well as being rich in calcium, ice cream contains

significant levels of lactose and amino acids such as

tbl0001 Table 1 Ice cream composition and energy levels compared to ‘Euroglace’ proposal

Nutrient Ice cream

Ice cream

(g per100 g) (Percentage energy) (g per 100 g) (Percentage energy)

Energy (kcal) 210 100 173 100

Protein 3.9 8 3.9 10

Fat 11.7 50 8.0 41

Available carbohydrate 21.0 40 21.0 49

From Souci SW, Fachmann W and Kraut H (1989) Food Composition and NutritionTables, 4th edn., p. 947. Stuttgart: Wissenschaftliche Verlagsgesellschaft

GmbHXL.

‘Euroglace’ proposal.

3234 ICE CREAM/Dietary Importance

lysine and arginine. These are known to enhance the

absorption of calcium and to promote bone min-

eralization. Although rich in some micronutrients,

ice cream is, in common with other milk-based

products, comparatively deficient in iron and vita-

mins C, D, and E. (See Amino Acids: Properties and

Occurrence; Lactose.)

Comparison of Dairy and Nondairy

Ice Cream

0014 Ice Creams made from cream or butter (dairy ice

creams) and from vegetable fat (nondairy ice creams)

are essentially comparable in nutritional value. There

are differences, however, in the vitamin A content,

which is higher in dairy ice cream, and the vitamin E

content, which is higher in nondairy ice cream.

0015 There are also differences in the proportion of

saturated and unsaturated fats present. Ice cream

made from palm oil is lower in saturated fat than

dairy ice cream, whereas ice cream made with coco-

nut oil has a higher saturated fat content than a

butterfat product. (See Fatty Acids: Properties; Vege-

table Oils: Dietary Importance.)

Sugar Content

0016Sugars are major ingredients in ice cream manufac-

ture and have an important influence on the nutri-

tional status of the product. Carbohydrates

contribute 40–50% of the calories in ice creams. Su-

crose is most widely used, but most ice creams con-

tain at least three types of sweetener: sucrose, lactose

(from milk) and maltodextrins (from corn syrup). The

preferred level of sweetness varies form country to

country, with products containing the equivalent of

between 13 and 19% of sucrose, and a total of up to

25% carbohydrate by weight. (See Sucrose: Dietary

Importance.)

tbl0002 Table 2 Micronutrient composition of ice cream and milk

Micronutrients (per100 g) Dairy ice cream

Pasteurized whole milk

Adult US RDA

Percentage of US RDA

supplied by 100 g of

ice cream

Water-soluble vitamins

Vitamin C (mg) 1 1 60 1.7

Vitamin B

or thiamin (mg) 0.04 0.04 1.5 2.7

Vitamin B

or riboflavin (mg) 0.25 0.17 1.8 13.9

Vitamin B

or pyridoxine (mg) 0.08 0.06 2.0 4.0

Vitamin B

or cobalamin (mg) 0.4 0.4 2.0 20

Nicotinic acid (mg) 0.13 0.08 20 0.7

Pantothenate (mg) 0.44 0.35

Biotin (mg) 2.5 1.9

Folate (mg) 7 6 200 3.5

Fat-soluble vitamins

Vitamin A or retinol (mg) 115 52 1000 11.5

Carotene (mg) 195 21

Vitamin D (mg) 0.12 0.03 10 1.2

Vitamin E (mg) 0.21 0.09 10 2.1

Macrominerals

Calcium (mg) 130 115 1200 10.8

Phosphorus (mg) 110 92 1200 9.2

Magnesium (mg) 13 11 350 3.7

Sodium (mg) 69 55

Chloride (mg) 110 100

Potassium (mg) 160 140

Sulfur (mg) N 30

Microminerals

Iron (mg) 0.1 0.05 15 0.7

Zinc (mg) 0.3 0.4 15 2

Copper (mg) 0.02 Trace

Selenium (mg) N 1 70

Manganese (mg) Trace Trace

Iodine (mg) N 15 150

N, the nutrient is present in significant quantities, but there is no reliable information on the amount.

From Holland B, Unwin ID, and Buss DH (1989) Milk Products and Eggs. Fourth Supplement to McCance and Widdowson’s The Composition of Foods. London:

Royal Society of Chemistry and Ministry of Agriculture, Fisheries and Food.

From National Research Council (1989) Recommended DietaryAllowances, 10th edn. Washington, DC: National Academy Press.

ICE CREAM/Dietary Importance 3235

Nutritional and Health Issues

0017 The nutritional issues relevant to sugars in ice cream

are as follows:

0018 the need for functional lower-calorie sweeteners;

0019 the interest in products more suitable for diabetics;

0020 the search for noncariogenic products.

Cariogenicity has not been discussed here because of

a lack of information specific to ice cream. Previous

extensive reports on nutritional aspects of the diet

in the UK and USA have commented on the role of

sugars in general in promoting the incidence of

dental caries. However, to put these problems in per-

spective, it should be borne in mind that ice cream

contributes only 1– 4% of the total intake of sugars

in the diet. (See Dental Disease: Role of Diet;

Sweeteners: Intensive.)

Nutritional Claims

0021 A number of products with specific nutritional claims

have been developed, e.g., lower-calorie ice creams

and diabetic products. The basis of these nutritional

claims, and the compositional changes needed to

support them, are considered below.

Lower-calorie Ice creams

0022 Standard ice creams already have a fairly low-calorie

density because of the high percentage of air and

water in the product. Nevertheless, further calorie

reduction is possible by reducing the fat or sugar

content, or by replacing some of the sugars by sugar

alcohols, or other synthetic sweeteners such as sac-

charin or Nutrasweet (aspartame).

0023 Three sugar alcohols – lactitol, maltitol, and Pala-

tinit (isomalt) – are now in manufacture as lower-

calorie substitutes for sugars. Compared to sugars at

4 kcal g

1

, maltitol provides only 3 kcal g

1

, and lac-

titol and Palatinit (a mixture of mannitol and glucitol)

only 2 kcal g

1

.(See Sugar Alcohols.)

0024 Total replacement of sugars by zero-calorie syn-

thetic sweeteners such as saccharin is, however, only

practical if some other ingredient can substitute for

the other functional characteristics normally pro-

vided by the sugars. Polydextrose, a new food ingredi-

ent, exhibits some of the functional properties of

sugars without contributing any sweetness to the

product. It is a randomly bonded polymer of dex-

trose, resistant to attack by acid and digestive

enzymes. Consequently, it is only partially metabol-

ized, with a calorie contribution of only 1 compared

to 4 kcal g

1

for saccharides. Polydextrose has been

cleared for use in ice cream by, for example, the Food

and Drug Administration (FDA) in the USA and by

the UK authorities, although regulations in the UK

prohibit its use in foods specially prepared for babies

or young children. (See Saccharin.)

Diabetic Products

0025Sorbitol and fructose are the most common substi-

tutes for sugars in products designed for diabetics.

However, synthetic sweeteners and the more recently

developed sugar alcohols are available as alternatives

(see above).

Importance of Ice Cream

0026The recommendations for a healthy and balanced diet

made by many governmental bodies emphasize the

importance of eating a variety of different foods and

the enjoyment of food. Ice cream can be delicious and

a pleasure to eat, but it is also a nutritious food. It

contains all the macronutrients and many micro-

nutrients, and is a valuable source of energy.

0027In terms of energy, a 50-g serving of ice cream

yields approximately 100 kcal. This is about that of

the same weight of whole milk yogurt but two and a

half times less than that of chocolate. Volumetrically,

owing to the inclusion of air, the ice cream portion is

twice as large as that of the yogurt and chocolate. For

a child with a RDA of 2000 kcal, a 50-g portion of ice

cream would provide 5% of the RDA of energy.

0028In conclusion, ice cream is particularly valuable for

its content of high-quality protein and easily assimi-

lated calcium. It provides many nutrients and can

make a useful, as well as enjoyable, contribution to

the daily intake of energy in a healthy and balanced

diet.

See also: Amino Acids: Properties and Occurrence;

Carbohydrates: Requirements and Dietary Importance;

Dental Disease: Role of Diet; Fats: Requirements; Fatty

Acids: Properties; Lactose; Protein: Requirements;

Saccharin; Sucrose: Dietary Importance; Sugar

Alcohols; Sweeteners: Intensive; Vegetable Oils:

Dietary Importance

Further Reading

Arbuckle WS (1972) Ice Cream, 2nd edn. New York: AVI

Publishing.

Olsen RE, Broquist HP, Chichester CO et al. (1984) Present

Knowledge in Nutrition, 5th edn. Washington, DC: The

Nutrition Foundation.

UK Committee on Medical Aspects of Food Policy (1989)

Dietary Sugars and Human Disease. London: Her

Majesty’s Stationery Office.

US FDA (1986) The Evaluation of Health Aspects of Sugars

Contained in Carbohydrate Sweeteners. Washington,

DC: US Food and Drug Administration.

3236 ICE CREAM/Dietary Importance

Microbiology

A Kambamanoli-Dimou, Technological Education

Institute, Larissa, Greece

Introduction

0001 Ice cream is composed of a mixture of milk products,

sweetening materials, stabilizers, flavors, or egg prod-

ucts, which are referred to as ingredients. The wide

variety of ingredients that may be used to produce

different kinds of ice cream and their microbiological

standard and quality greatly affect the quality of the

ice cream. The specific production, processing and

postprocessing storage, and storage or distribution

conditions also considerally affect the quality of the

final product. So, the microbiological quality of ice

cream depends on many factors, the most important

of which are described here.

Raw Materials (Major Components and

Additives)

0002 Although the best ice cream can be made from cream,

concentrated or condensed milk, sugar, stabilizer, and

high-quality flavoring, ice cream manufacturers have

found it highly desirable to use a variety of ingredi-

ents available from numerous sources. Any of these

can contribute bacteria, molds, and yeasts to the final

product. Of course the ice cream mix is pasteurized

before freezing. This heat treatment gives an adequate

reduction in bacterial numbers as well as the destruc-

tion of pathogenic organisms. It cannot, however,

entirely correct the hygienic quality of poor ingredi-

ents. So, carefully selected ingredients are essential for

the manufacture of ice cream of the highest quality.

0003 Liquid milk, cream, skim milk, and concentrated

skim milk should have been subjected to efficient heat

treatment, and must be kept under refrigeration and

be used properly. Otherwise, they may contain appre-

ciable numbers of bacteria, including some which

are pathogenic (Mycobacterium spp., Streptococcus

spp.). Naturally, the main organisms present in these

dairy materials, which have been handled and stored

under sanitary conditions, are a few spore-forming

bacilli, micrococci, psychrotrophic, and thermoduric

microorganisms. They are not a major health hazard

but they may sometimes spoil the mix. Milk powders

may also contain large numbers of spore-forming

bacilli or may be contaminated by salmonellae.

Numerous outbreaks of food poisoning attributed to

salmonellae or staphylococci from milk powder pro-

vide evidence that these pathogens do on occasions

survive in the final product. A special hazard of

staphylococcal enterotoxin in ice cream may be pre-

sent if whey powder is used as a source of milk solids.

Careful control and storage of these powders under

dry and cool conditions are necessary. (See Cream:

Types of Cream; Milk: Liquid Milk for the Consumer.)

0004Several sugars are used as sweetening ingredients.

These products rarely undergo microbial spoilage if

properly prepared, processed, and stored. Certain

yeasts and molds could be the principal spoilage

flora, though some species of bacteria have also been

suggested as possible spoilage problems, including

Bacillus and Leuconostoc species. Also, sugar syrups

are used. Osmophilic yeasts may be able to grow in

these syrups, and molds may grow on the surface, so

tests for yeasts should be carried out in order to

minimize contamination of the ice cream from these

ingredients.

0005Butter and butter oil (anhydrous milk fat), used as a

source of milk fat, are made from pasteurized cream

so they should not contain pathogenic bacteria, and a

high microbiological quality is to be expected when

satisfactory hygienic conditions are applied during

their production and if they are properly handled.

Relatively small numbers of mesophilic bacteria, coli-

forms, and lipolytic organisms, particularly the Pseu-

domonas species responsible for butter spoilage, as

well as molds and yeasts, can be found. Butter com-

monly is kept refrigerated and during commercial

storage is kept at about 20



C, at which temperature

no microbial growth can occur. For these reasons

bacteria usually do not grow in butter, and when

they do, their growth is not extensive. The flavor of

good butter is so delicate, however, that small

amounts of growth may cause appreciable damage

to the flavor. When satisfactory hygienic conditions

are applied during the production of the above ingre-

dients and if they are properly handled (storage tem-

peratures of no more than 20



C for butter, and dry,

refrigerated conditions for butter oil), combined with

tests for the above-mentioned microorganisms, a high

microbiological quality will be insured. Fats other

than milk – commonly vegetable fats – may also be

used. The high temperature used during their process-

ing and their low moisture content give raw materials

containing very few microorganisms. Dry, refriger-

ated conditions should be used for their storage.

(See Butter: The Product and its Manufacture.)

0006Stabilizers do not constitute an important source of

bacteria, as they are usually produced by methods

involving high temperatures. So, if they have been

packaged under hygienic conditions they do not con-

tribute to microbiological contamination of the ice

cream mix. Attention must be paid to gelatin,

which, as an animal product, may be a hazard if

ICE CREAM/Microbiology 3237

produced under insanitary conditions, so it should be

obtained from a reputable supplier and kept under

cool, dry conditions. Emulsifiers should not present a

problem, except for eggs, which may be contamin-

ated by Salmonella spp., and pasteurization is re-

quired to avoid any hazard arising from their use.

(See Salmonella: Properties and Occurrence.)

0007 Fruits (fresh, canned, or frozen) and nuts, choc-

olate, and cocoa, flavoring materials such as vanilla,

colors and so forth are added to ice cream or are used

as coatings. All of them are potential sources of

hazard, particularly if they are added after the heat

treatment of the mix. Fresh fruits are used and yeasts

and molds, which predominate their microbial flora,

may be a problem. Fruit pulps and concentrates are

commercially available and manufactured at a high

standard of hygiene. Canned fruits, because of their

heat treatment, should be of satisfactory microbio-

logical standard. Several types of nuts may be used in

the ice cream or as a coating. They could be a hazard

because they may contain molds and, possibly, myco-

toxins. Coconuts can also contain salmonellae. For

these reasons, it is much better if all these materials

are used after heat treatment (roasted nuts, for

example, or pasteurized chocolate), especially if they

are added to the mix after its pasteurization. Also,

they should be stored under cool, dry conditions. The

examination of these materials should include a

visual inspection and the enumeration of mesophilic

bacteria, coliforms, yeasts, and molds.

0008 Colors, if manufactured carelessly, may cause

problems of microbial origin, especially when they

are added after pasteurization. This can be avoided

if they are obtained from a good supplier and stored

properly.

0009 In conclusion, a very wide variety of ingredients are

used in ice cream manufacture and variations in their

quality affect the microbial load of the final product.

The need to use high-quality raw materials, pur-

chased from a reputable supplier, carefully stored

under good conditions which will not allow the pro-

liferation of microorganisms, is evident. In addition,

it is suggested that appropriate microbiological tests

should be performed on raw materials, and the use of

strict stock rotation is essential.

Hygiene During Production

0010 The manufacture of ice cream is a relatively complex

operation which includes a series of steps, all of which

have some effect on the microbiological quality of the

final product. So, a high-quality ice cream demands

good ingredients along with sanitary conditions of

processing, freezing, hardening, and distribution. As

all these factors are important, they must be carefully

controlled in order to produce a safe product, safe-

guarding the consumer’s health.

0011All the ingredients, after they have been weighed or

measured, are blended together to make a liquid mix.

This mixture is then subjected to a heat treatment

process, which in most countries is specified by legal

requirements. This heat treatment renders the mix

substantially free of vegetative microorganisms,

killing all pathogens likely to be present. The ice

cream mix is always homogenized, often as a step in

the pasteurization process. The homogenizer is a

complex piece of equipment and must be carefully

cleaned and disinfected each time it is used, or the

mix may be seriously contaminated. It is therefore

suggested that homogenization of the ice cream mix

is carried out before it is finally heat-treated, where

possible. Then follow cooling and aging of the mix.

After the aging period, the mix is passed to the freezer

where it is subjected to considerable agitation and

reduction in temperature, as well as incorporation

of air. On leaving the freezer, the ice cream will nor-

mally be packaged (in family packs, individual retail

packs, or other forms), frozen hard in wind tunnels at

40



C or in hardening rooms, and then kept at a

temperature of about 30



C both until and during

distribution. Some ice cream is sold directly from a

dispensing freezer as ‘soft-serve’ ice cream in cones,

or in various types of made-up desserts in restaurants

and cafe

s, or from vehicles complete with their own

electricity generation equipment.

0012The overall operation is relatively complex and

each of the steps taken may have some influence on

the microbiological quality of the final product. The

processing methods or equipment may be responsible

for wide variations in bacterial counts.

0013Ice cream mixes should not be kept for more than

1 h at a high temperature (more than 7



C) before

being pasteurized, in order to avoid the proliferation

of organisms carried in the ingredients. During pas-

teurization, time as well as temperature should be

strictly observed in order to avoid on the one hand

excessive heat treatment, which may lead to undesir-

able flavor changes, and on the other hand, to insure

the destruction of pathogenic organisms and the ad-

equate reduction of total bacterial numbers. Cooling

of mixes to 0–2



C almost completely eliminates the

possibility that microorganisms can grow in the mix.

Cooling of mixes to such low temperatures is done

efficiently in direct-expansion-type swept-surface

heat exchangers. Such cold temperatures add several

days to the shelf-life of mixes sold to other firms for

freezing. The cooling must also be rapid and the mix

must be kept at that low temperature until it is frozen,

otherwise, any viable organisms may proliferate. This

can lead to a product with a high microbial count and

3238 ICE CREAM/Microbiology

possibly to a disease outbreak. The same danger

exists if the cooling system fails during the aging of

the mix. In this case, the mix must be discarded

because, although a repasteurization will kill the or-

ganisms, it will not destroy possible toxins already

present. Normally, the mix should be frozen within

24 h of heat treatment, as undue prolongation of

storage may lead to proliferation of psychrotrophic

organisms, with a serious risk of spoilage of the mix.

0014 The incorporation of air into the ice cream mix

during the freezing process may cause airborne con-

tamination, so air must be admitted through filters to

prevent the ingress of organisms. For some products,

the ice cream is blended with water ice on leaving the

freezer, and may be frozen on a stick or in a cone

(single portions) and covered with a chocolate or

flavored couverture, together with broken biscuits

or nuts. Addition of ingredients to the pasteurized

mix constitutes a critical control point in ice cream

manufacture, because no further lethal process is

given to the product. Therefore, it is important that

all operations at this point be done in a sanitary

manner and that ingredients be free of pathogenic

microorganisms. The most likely pathogens to be

encountered at this point are Listeria monocytogenes

and Salmonella.

0015 The packaging materials may occasionally cause

trouble, but there should be no problem if they have

been handled and stored under hygienic conditions.

0016 In addition to careful operation of the equipment,

proper cleaning and sanitizing of the plant and equip-

ment are of great importance; therefore, special care

is demanded. All plant equipment that comes into

contact with ice cream or ice cream ingredients must

be carefully cleaned and sanitized immediately after

use; this is usually done at the end of each day’s

operation and before it is used again or it may even

be necessary to clean the plant thoroughly before

further processing during the same day. Not only is

the processing equipment important, but ancillary

equipment, in particular at the final sales point,

must be kept in a satisfactory hygienic condition.

Poor cleaning and sanitizing of the plant and equip-

ment may lead to pockets of ice cream residues where

intense proliferation occurs, which results in reconta-

mination of the pasteurized mix with a large number

of bacteria. For the ordinary soft-serve or dispensing

freezer, manufacturers usually lay down strict cleaning

routines which must be followed carefully. Isolation

of L. monocytogenes from an ice cream plant shows

that dangerous microorganisms are able to survive in

the food-processing environment and improved and

precisely targeted cleaning and disinfection practices

are of great importance in the eradication of those

microorganisms.

0017Clean surroundings are essential if equipment is to

be kept in a hygienic condition. All rooms, especially

toilets and locker rooms, must be kept as clean and

sanitary as the area immediately surrounding the

packaging equipment. Surrounding activities (e.g.,

sewerage plants, rubbish tips) often represent poten-

tial sources of contamination, and birds, rodents, and

insects are very important vectors of such contamin-

ation. In addition to preventing access of pests to the

process area, it is important that the factory yard is

kept free of food waste, rubbish, and spilled material

that might attract birds, rodents, and insects. All such

material should be kept in lidded containers and re-

moved on a daily basis. Pet animals, such as dogs and

cats, similarly have no place in a food production

factory.

0018Operations must be segregated to minimize the

chances of pathogenic microorganisms being carried

from raw materials to finished products. Persons

handling raw milk or cream must not be allowed

access to rooms where pasteurized products are ex-

posed unless those persons have first changed their

clothes completely and have disinfected themselves.

Room air pressures should be maintained at succes-

sively higher levels, from the mix room to the pro-

cessing room, to the freezing operation, and to the

packaging operation. Thus, the flow of air will be

away from the most critical area, i.e., the packaging

room. The supply of hot and cold water must be

unrestricted and facilities for disposal of both liquid

and solid wastes must be adequate. All water that is

used in food formulation, or will be used on (or could

gain access to) food contact surfaces should be of

potable quality and be stored in enclosed tanks and

distributed in piping that is completely segregated

from other pipe systems. Potable water may be de-

rived from public mains supplies or other sources

such as boreholes which must be protected against

contamination by surface water or underground con-

tamination from drains, seeping from farm or indus-

trial tips, and similar potentially hazardous areas.

Whatever its origin, the water should be routinely

examined microbiologically at point of entry to the

site and at the point of use, particularly if there is

on-site storage.

0019The hygienic standards of the workforce are crucial

to the ice cream manufacturer. No worker who has not

been adequately taught the necessities of personal hy-

giene and approved practices should be allowed to

perform tasks in the plant. Every employee must dress

in a clean uniform, wear a hair restraint, wash and

sanitize hands, disinfect footwear on entry to the pro-

cess area, and refrain from touching any product con-

tact surface without properly sanitizing the hands, or

gloves if worn. Proper sanitary practices are essential to

ICE CREAM/Microbiology 3239