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

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milk (up to 12% fat). In the case of Speisequark, it is

usual to add the desired amount of cream to the low-

fat curd after separation of the whey. This is impos-

sible in the case of highly structured products such as

full-fat cottage cheese. Besides milk, considerable

amounts of buttermilk are used nowadays to produce

fresh cheeses. Owing to the fact that most fresh

cheeses have a soft consistency, reconstituted milk

from low-heat powder is also a rather good raw

material; however, some CaCl

should be added.

Some varieties of lactic cheese are prepared from

milk–whey mixtures.

0013 As already mentioned, heat treatment of the milk

varies between zero and high heating, according to

the individual products and the technology in use.

However, it should be remembered that fresh cheeses

do contain a low amount of their own flavor com-

pounds and they are very sensitive to off-flavors

from the milk used. Only raw milk of the best quality

yields fresh cheeses with the typical and delicate

flavor.

Acidification

0014 Some (Mediterranean) fresh cheeses are prepared by

direct acidification with lemon juice or vinegar, but

nowadays commerically available lactic acid may be

used, and even phosphoric acid has been mentioned

as an acidulant. However, most fresh cheeses are

produced by acidification of the milk with lactic

acid bacteria, i.e., by fermentation. In the northern

countries, mesophilic starters are used and in oriental

areas with warm climates, thermophilic microorgan-

isms, or even pure yogurt cultures, are used.

0015 Industrial production of fresh cheeses involves the

use of selected strains of Lactococcus lactis, and L.

lactis subsp. cremoris to develop lactic acid, and

sometimes Lc. lactis spp. lactis (L. lactis biovar.

diacetylactis)orLeuconostoc mesenteroides subsp.

cremoris to form flavor compounds. To avoid prote-

olysis, which causes loss in yield and initiates off-

flavors, Lc. lactis spp. lactis may be removed from

some selected starters.

0016 With thermophilic starters (optimum 43



C) it is

easier to limit acidification; Lactobacillus acidophilus

is a typical species in use. For example, cultures with

limited acidification not lower than pH 4.8–5.0 are

produced by Biogarde

containing Streptococcus

thermophilus, Lactococcus lactis, Lc. lactis biovar.

diacetylactis, Leuconostoc mesenteroides subsp. cre-

moris, Lactobacillus acidophilus and even Bifidobac-

terium bifidum. Labaneh and labneh, which are very

popular in the Middle East, are acidified with thermo-

philic yogurt starters. Industrially used starters should

not produce gas (CO

); this avoids problems in the

production line, especially in the separators. (See

Starter Cultures.)

0017Normally, 0.5–1% starter is added to the milk at

about 30



C. When pH 6.3 is reached (after about

1.5 h), rennet may be added (in this case, the milk is

stirred well to distribute the enzyme), and in about

16 h the desired acidity of pH 4.5–4.55 is reached.

During acid development, the milk should not

be stirred. Clearly, acid development is strongly

dependent on some important factors, which are

part of the typical and individual technology for the

different unripened cheeses.

Curd Formation and Treatment

0018Rennet, if any, is used in small amounts, e.g., 0.5–

1.0 ml (1:10 000) per 100 l of milk for quarg.

0019Pure acid casein curds are rather sensitive to heat, a

temperature around 43



C and a pH of 4.3 seem to be

optimal for whey drainage. If the temperature is only

a few degrees higher, the curd changes from dry to

smeary. After cutting, traditionally prepared lactic

curds are therefore normally filled into cheesecloths

and drained at room temperature, and afterwards at a

low temperature (4–5



C) for many hours.

0020In the case of renneted acid curds, heating to 50–



C for 1.5 h (cottage cheese) or even 60–64



C for

4–5 min (quarg) improves syneresis of the coagulum.

Owing to these effects, cottage cheese is prepared in a

granular form; the curd is washed three times with

water at decreasing temperature (30



C, 16



C, 4



to remove lactose and to stabilize the pH and shelf-

life.

0021Centrifugation of quarg curds is performed at

about 40–44



C; ultrafiltration is performed over the

same range of temperatures or even higher. Cooling of

quarg takes place in special tubular coolers, and the

product is transported through the line by positive

pumps. At the end of the line, a quarg mixer may be

installed to enrich the product with cream, salt, fruits,

stabilizers, etc. Fresh cheeses are normally packaged

in plastic containers, glass jars, etc., preferably under

aseptic conditions. Some types of fresh cheese with a

high content of dry matter are sold as small, round, or

wedge-shaped bodies packaged in foil.

0022This is certainly true for the high-fat cream cheeses.

They are produced from homogenized milk contain-

ing 10% or more fat (with 9% fat, the curd has the

same specific weight as whey, so that centrifugal sep-

aration is impossible!). The acidified milk is heated to



C before separation. The total solids content of

the hot drained curd is 44%, and after salting and

cooling, it becomes a viscous mass due to crystalliza-

tion of fat.

1106 CHEESES/Quarg and Fromage Frais

Miscellaneous Products

0023 Cottage cheese represents the most structured type of

lactic cheese. ‘Dry curd’ quality (< 0.5% fat) is pro-

duced from skimmed milk; cottage cheese (low-fat)

contains 0.5–2% fat, and cottage cheese itself usually

contains > 4% fat. It is normally produced by treating

the grains with a cream dressing. According to the

size of the grains, it is distinguished as Californian-

style, popcorn-style, and country-style, as well as

large- and small-curd style. Block-pressed cottage

cheese is called farmer’s cheese.

0024 Although cottage cheese is slightly salted (1%

NaCl), the shelf-life is often below 2 weeks, owing

to the rather high pH value and sometimes poor

bacteriological quality of the wash water. In Ger-

many, products with a fat in dry matter up to 20%

are made, and manufacturing technologies involving

ultrafiltration of the milk are also applied.

0025 Quarg (Quark, Topfen, Koarg, Kwarg, Twarog,

Tvorog, Taho, lactic cheese, fromage frais, etc.) is

available with different levels of fat, up to 45% in

the dry matter. With increasing fat content, the con-

sistency changes from crumbly-dry to smooth, but

this texture can be influenced by technology (e.g.,

dry-matter, casein, and whey protein content). A

foamed quarg is named Bresso. Whipped quarg with

not more than 15% dry matter is fromage frais battu

maigre. Baker’s cheese is characterized by a high dry-

matter content (22–26%). Schichtka

se, like Cam-

bridge and York, is prepared from layers of low-fat

and high-fat lactic curd. Danish smoked quarg is

named Rygeost.

0026 Typical lactic curd, fresh cheeses with a high fat in

dry-matter content are cream cheese (70% fat in dry

matter), Petit-Suisse (> 70% fat in dry matter) and

Demisee (40% fat in dry matter), Neufcha

tel (55%

fat in dry matter), Doppelrahmfrischka

se (< 85% fat

in dry matter) and double cream cheese (> 65% fat in

dry matter). Some of these products are stabilized

with hydrocolloids, and the milk is homogenized.

Products such as Philadelphia, Gervais, Boursin, and

Le Tartar (with herbs and spices) are internationally

distributed.

0027 A very-high-fat Italian fresh cheese is mascarpone

(Mascherpone). It is produced from full-fat cream,

heated to 90



C, and acidified with citric acid. Whey

drainage is performed at 8–10



C for 12–18 h. In the

new Sordi process, cream (40–60% fat) is pasteur-

ized, mixed with milk concentrate from ultrafiltra-

tion, and acidified with citric acid in heated vats.

After careful stirring, the product is packaged and

stored for about 12 h in the cold to crystallize

the fat. Mascarpone is very popular for sweet des-

serts.

0028Ricotta was prepared originally by the direct acid-

ification of heated cheese whey from ewes’ milk

(ricotta di pecora). Many varieties of ricotta are

now available, mainly from cows’ milk (ricotta di

vacca). The consistency varies between soft and dry

(ricotta secca). Salted varieties (ricotta salata), as well

as the smoked cheeses, are used in the kitchen,

whereas the unsalted product (ricotta tipo dolce),

like the baked ricotta (ricotta salata al forno), are

consumed directly as appetizers or desserts. Ricotta

is named requeso

n in Spain and requeijao in Portugal.

0029Queso blanco (queso del paı

s, queso fresco) is also

available in many varieties in Spanish-speaking coun-

tries, but is now also manufactured in the USA. It is

produced by a combined heat-acid process (82



Cand

pH 4.6–4.7). Citric acid is said to give the best results,

but acetic acid is the most popular acidulant. This

cheese can be fried without melting, and is used in the

preparation of snack foods; with spices and tomato

sauce or chilli sauce, it is consumed fresh. The

organoleptic qualities can be improved using yogurt

starters instead of mesophilic starters. The moisture

content is about 50–54%. (See Acids: Natural Acids

and Acidulants.)

0030Yogurt starters are used exclusively in the produc-

tion of labaneh and labneh. Labaneh is the pure acid

curd from skimmed milk, and it can be stored for a

long time in olive oil. Labneh is prepared from full-

cream milk by acidification and by rennet coagula-

tion. The dry-matter content is approximately 40%.

These products are the Middle East equivalents of

quarg.

0031Last, but not least, the Swiss Zieger (named Seirass

in Piemont, Ce

rat in Savoy) should be mentioned.

Originally prepared by heating acidified whey, they

are now also produced from mixtures of milk and

whey, or even from skimmed milk. The cheese is white

or somewhat yellow, spreadable, and crumbly-soft.

See also: Acids: Natural Acids and Acidulants; Casein

and Caseinates: Uses in the Food Industry; Emulsifiers:

Phosphates as Meat Emulsion Stabilizers; Lactic Acid

Bacteria; Membrane Techniques: Principles of

Ultrafiltration; Pasteurization: Principles; Starter

Cultures; Whey and Whey Powders: Protein

Concentrates and Fractions

Further Reading

Drewes K (1952) Die Herstellung und Beurteilung von

Sauermilchquark. Hildesheim: Mann-Verlag.

Eck A and Gilles JC (eds) Le Fromage: de la Science a

l’Assurance-Qualite

, 3rd edn. Paris: Lavoisier.

Lehmann HR, Dolle E and Bu

cker H (1984) Prozesslinien

zur Herstellung von Frischka¨se. Oelde: Westfalia Separ-

ator.

CHEESES/Quarg and Fromage Frais 1107

Spreer R (1998) Milk and Dairy Product Technology. New

York: Marcel Dekker.

Stieger W (1920) Anleitung zur Quarkbereitung und zur

Handka¨sefabrikation, 3rd edn. Berlin: Paul Parey.

Processed Cheese

A Gouda and A Abou EI-Nour, Suez Canal University,

Ismailia, Egypt

Introduction

0001 Cheese in general, including processed cheese, is rich

in different nutrients such as proteins, fats, minerals,

and vitamins. It is reported that utilization of proteins

of processed cheese is better than proteins of natural

cheese.

0002 Processed cheese, compared to natural cheese, is a

new product which originated at the beginning of the

twentieth century. Spoilage of cheese exported to

distant places was the motive behind the trials to

improve the shelf-life of cheese. Some of these trials

succeeded in prolonging the keeping quality of soft or

even semihard cheese by applying heat treatment, but

the situation was not the same for hard cheese, due to

shrinkage of the cheese protein by heat and separ-

ation of the water and fat phases. In 1912–13, the

Swiss workers, Walter Gerber and Fritz Settler, solved

these problems by heating hard cheese to which

sodium citrate was added. This treatment was the

real invention of processed cheese. Later, phosphate

salts were introduced as emulsifying salts, and the

development of the processed cheese industry con-

tinued and different patents were granted. In 1916

Kraft established the first commercial factory for pro-

cessed cheese in the USA. Production and consump-

tion of processed cheese increased steadily and, today,

large tonnages of natural cheeses are converted to

processed cheese. The production and consumption

of processed cheese products showed a constant in-

crease during the period from 1990 to 1994 (Table 1),

notably in the European Union, the USA, and Japan.

Production of processed cheese affects – directly or

indirectly – dairy production in general in the

following ways:

0003It encourages cheese production as a base for the

manufacture of processed cheese.

0004It makes it possible to use second-grade cheese or

cheese with mechanical or surface defects.

0005At peak times of cheese production, young cheese

could be precooked and stored until it is used for

processed cheese. In this way it is possible to

control ripening and save the cost of storing fresh

cheese for long periods in expensive stores.

0006Processed cheese products have many advantages

over natural cheese:

0007In most cases, processed cheese can be stored

without refrigeration.

0008Processed cheese can be produced in different

shapes, flavors, and physical properties, e.g., soft,

firm, spreadable, in variable and attractive pack-

ages, and it has a relatively long shelf-life.

0009It is free from pathogenic microorganisms.

tbl0001 Table 1 Production (A) and consumption (B) of processed cheese (1000 tonnes)

19 9 0 19 92 19 9 4

ABABAB

Belgium 42.8 14.6 54.9 16.1 51.2 17.8

Denmark 12.5 3.6 13.4 5.2 15.2 5.6

Germany 152.7 112.8 164.5 119.5 164.1 116.6

Spain 32.0 31.8 36.2 35.6 39.2 38.1

France 99.1 57.2 105.7 63.2 119.4 62.4

Ireland 8.6 9.6

Italy 20.3 20.3 20.2

Netherlands 33.1 11.6 32.1 10.8 31.2 9.1

Portugal 8.0 3.5

United Kingdom 20.4 44.7 19.8 47.9 19.7 51.5

European Union 424.5 309.5 460.0 369.3 474.0 376.6

USA 1070.1 1101.3 1147.7

Japan 74.0 76.0 85.0 87 91.0 94.0

Reproduced from Hetzner E and Richarts E (1996) The international market for processed cheese. Bulletin of the International Dairy Federation 316: 16–26,

with permission.

1108 CHEESES/Processed Cheese

Principles of Processed Cheese-Making

0010 Processed cheese is made by heating natural cheese of

different types, age, and maturity in the presence

of suitable emulsifying salts and with the help of

mechanical agitation. In making processed cheese,

the insoluble calcium para-casein gel of the natural

cheese, under the influences of heating and the action

of emulsifiers and agitation, is changed to a para-

casein sol – a homogeneous, flowing mass. This sol

is changed again to a gel by the influences of cooling

and polymerization forces resulting in processed

cheese. By understanding the role of different factors

related to processed cheese manufacture, it is possible

to control and select the characteristics of the end

product – soft, firm, sliceable, spreadable, etc.

Types of Processed Cheese

0011 Processed cheese can be grouped into three main

types.

Pasteurized Processed Cheese

0012 Pasteurized processed cheese is made from one or

more lots of cheese of the same or different varieties.

Water, NaCl, coloring, and flavoring materials may

be added. The moisture content of the processed

cheese may exceed by not more than 1% the

maximum permitted in the natural cheese from

which it is made, while the fat content may not be

less than that of the natural cheese. Processed cheese

bears the name of the natural cheese from which it is

made. The processing temperature varies from 80 to



C and the pH of the end product ranges from 5.4

to 5.6. Good processed cheese has a smooth, com-

pact, firm body, and can be cut into slices.

Pasteurized Processed Cheese Foods

0013 Processed cheese food resembles the above processed

cheese but contains more moisture and less fat.

Optional ingredients may be added, including dried

whey, dried skim milk, lactose, and organic acids. The

moisture content should not exceed 44% and the fat

content should be not less than 23%. The processing

temperature is normally 85–90



C and the pH of

the processed product is 5.6–5.8. Processed cheese

food has a softer body and milder flavor than pro-

cessed cheese. (See Lactose; Whey and Whey

Powders: Production and Uses.)

Pasteurized Processed Cheese Spread

0014 The constituents of pasteurized processed cheese

spread are similar to those used for making processed

cheese food, but it contains more moisture in order to

achieve a soft body and spreading properties. In many

standards, the moisture content should not exceed

60% and the fat should be not less than 20%. This

cheese is normally processed at a high temperature

(85–95



C) in traditional cookers, and has a pH be-

tween 5.7 and 5.9. Binding agents may be added in

amounts not exceeding 0.8% of the finished product

to improve water retention. Processed cheese spreads

are characterized by a mild flavor, and a smooth, soft

body that is easy to spread at room temperature.

Processed Cheese Analog

0015Recently, a new version of processed cheese has been

introduced under the name of imitation or analog

processed cheese: the natural cheese and fat are re-

placed by caseinates, vegetable proteins such as soya

bean protein, and a suitable vegetable oil. The pro-

cessing conditions, i.e., emulsifiers, heating tempera-

ture, and pH, are quite similar to that reported for

processed cheese spread. (See Casein and Caseinates:

Uses in the Food Industry; Soy (Soya) Beans: Process-

ing for the Food Industry; Vegetable Oils: Types and

Properties.)

0016Processed cheese analog may be produced either as

block or spread and should have good melting prop-

erties and good shredding or slicing behavior. A small

amount of free oil may be acceptable, particularly for

use in pizza making. Rennet casein is commonly used

in making processed cheese analog as it gives ideal

properties to the cheese, especially casein, which con-

tains 0.1–0.3% lactose and has a particle size of

about 30 mesh.

0017Analog processed cheeses have some advantages

compared to processed natural cheese:

0018Cheaper ingredients may be used.

0019A wide range of suitable proteins is available.

0020Ingredients can be stored for a long time without

spoilage.

0021The properties of the final product can be con-

trolled.

0022It is more stable and has greater flavor.

0023The limits for moisture and fat in processed cheese

are quite flexible and may vary from country to coun-

try according to specific standards implemented in

each country.

Raw Materials for Processing

0024The main materials used for the manufacture of pro-

cessed cheese include natural cheese, emulsifiers,

water, and other additives.

CHEESES/Processed Cheese 1109

Cheese

0025 Two main factors should be considered in

selecting the cheese for processing – type and degree

of maturity.

0026 Type of cheese In general, all rennet-curd cheeses,

i.e., soft, semihard and hard cheese, can be used for

making processed cheese, but it is common practice to

use only hard and semihard cheeses; soft cheeses are

only used for flavoring. The selected cheese should be

checked for dry matter, fat, pH, protein content, age,

and degree of maturity. In many countries, Cheddar

cheese is preferred as a main base for processed

cheese. A single type of natural cheese can be used

but it is more common to use more than one variety of

cheese with the aim of giving the desired body, tex-

ture, and flavor to the final product. It is worth men-

tioning that good-quality natural cheese is essential

for producing high-quality processed cheese. Second-

grade cheese or cheese with mechanical defects can be

used, but cheese with a putrid or rancid flavor must

not be used, even in small quantities, as the fault will

appear in the processed cheese.

0027 Degree of maturity In general, hard cheeses may be

grouped according to the degree of maturity:

0028 Fresh, green or young cheese – 1–2 weeks old.

0029 Medium ripened cheese – 2–4 months old.

0030 Ripened cheese – over 4 months old.

0031 Natural cheeses of different degrees of maturity

are selected for processing to obtain the required

composition, physical properties and flavor in the

processed cheese. Young cheese has a high level of

intact casein as most of the protein has not been

hydrolyzed to soluble components; the ratio between

insoluble casein nitrogen and the total nitrogen is

called relative casein. The higher the relative casein

(90–95% in young cheese), the more stable the result-

ant processed cheese will be. Processing young cheese

results in processed cheese with a long structure, and

the body tends to be smooth or firm depending on the

moisture content. It is difficult to use only young

cheese in processing, as it will result in a processed

cheese of ‘flat’ flavor.

0032 However, the long structure of young cheese can be

altered by the action of various factors during pro-

cessing. These factors are mainly related to the use of

suitable emulsifying salts together with prolonged

agitation during the thermal process. Changing the

long structure of young cheese to a short one with

good spreadability is known as creaming. During the

creaming process, the large casein particles, with a

low level of hydration in young cheese, are split into

small casein particles with increased surface area,

hydration, and good spreadability. However, exces-

sive hydrolysis of cheese casein when making pro-

cessed cheese will lead to an overcreaming defect in

the cheese texture. Thus, young cheese, with proper

processing, is convenient as the main base for making

processed cheese spreads containing a high level of

fat-in-dry-matter (60–70%); young cheese also con-

tains a high level of intact casein necessary for stabil-

ity. It is reported that stable processed cheese should

contain not less than 12% intact casein. In a recent

study in the authors’ laboratory processed cheese

spreads containing 60–65% fat in dry matter, 60%

moistures and pH 5.85 were made from cheese blends

containing 9.8–10.2 of intact casein. The resulting

spreads had a good body and texture and could be

packed in triangular portions without sticking in

the foil. The spread was stable (without fat or

water separation) through the storage period. As the

ripening cheese progresses, its relative casein content

decreases as a result of proteolysis; hence, fully

ripened cheese is normally added to the processed

cheese blend at a level of 10–20%, mainly to give

the desired flavor. It is too difficult to use fully ripened

cheese as the main base for processing, as its intact

casein is already degraded and is not able to form a

stable emulsion.

0033Also, use of too much of a very mature cheese, which

contains considerable amounts of low-solubility

amino acids as tyrosine, results in precipitation of

these free amino acids as white crystals within the

processed cheese structure.

0034Normally medium-ripened cheeses are blended

with young cheese in different ratios to make

processed cheese spread. If a high percentage of

medium-ripe cheese is used in a processed cheese

spread blend, there is no need for extensive processing

to achieve the necessary creaming properties as the

intact casein is, to some extent, already hydrolyzed.

Different ratios of young medium, and fully ripened

cheese have been reported for the manufacture of

processed cheese products. These ratios are not

fixed figures, and may vary according to the type,

characteristics, and composition of the natural

cheese; they may also vary if other dairy products,

such as milk or whey powder, are used in the blend.

Some typical blends are presented in Table 2.

0035The storage of cheese for ripening is rather expen-

sive; hence, many attempts have been made to render

young cheese, or even rennet curd, suitable for pro-

cessing a few days or weeks after manufacture. The

addition of lipolytic and/or proteolytic enzymes has

been investigated, cooking the curd in a lactic acid

solution. There has been success in using a hard

cheese with a low pH (4.8–5.0) a few days after

1110 CHEESES/Processed Cheese

manufacture as the main base for a good processed

cheese spread, aiming at the release of calcium from

the curd. This process has been employed on a com-

mercial scale. (See Enzymes: Uses in Food Processing.)

0036 Also, ultrafiltered retentates have been used as a

part of the blend for processed cheese. Many studies

reported that 60–80% of processed cheese blends

could be replaced by ultrafiltered retentate.

Emulsifying Salts

0037 Natural cheese is basically an oil-in-water emulsion,

stabilized by cheese protein. Heating and agitation, or

changing the pH, will affect the protein which may

lose all or part of its ability to effect stabilization;

defective texture, water and fat separation will

occur. In the presence of emulsifying salts, the separ-

ated water and fat are reincorporated into the cheese

mass, resulting in a homogeneous mixture. As the

emulsifiers (melting salts) work mainly on the cheese

protein (casein) they have a direct effect on the phys-

ical properties of processed cheese. The action of

emulsifiers is through the displacement of the calcium

of the insoluble para-caseinate by sodium ions,

resulting in a more soluble casein. The role of emulsi-

fying salts in processed cheese manufacture can be

summarized as follows:

0038 Removal of calcium from the protein system

0039 Dispersion of the protein

0040 Hydration and swelling of the protein

0041 Control and stabilization of the emulsion system

and the pH of the cheese

0042 Control of spoilage of the cheese

0043 (See Emulsifiers: Phosphates as Meat Emulsion

Stabilizers; Uses in Processed Foods.)

0044 The major emulsifying salts which are used on a

large scale are the sodium salts of citrates, monopho-

sphates, diphosphates, and polyphosphates. Sodium

aluminum phosphate is also used. Some emulsifying

salts are listed in Table 3.

0045 It is common practice to use a mixture of emulsify-

ing salts rather than one salt to obtain the general

desired characteristics. The amount of emulsifiers

used in processed cheese is normally 2–3%, de-

pending on type, maturity, and amount of natural

cheese in the blend. It has been reported that some

emulsifying salts, especially phosphate, have a

bacteriostatic effect on some microorganisms and

accordingly improve the shelf-life of the processed

cheese.

Water

0046Water is very important for producing a stable emul-

sion. Emulsifying salts need water to dissolve and act

properly on the casein. Water is added to the blend to

give the required water content in the processed

cheese. In calculating the amount of water, it should

be borne in mind that heating by direct steam injec-

tion will add some condensed water to the blend.

Water may be added at the start of processing, as in

the case of block-processed cheese, or in portions, as

for processed cheese spread. The addition of only part

of the water at the start of processing increases

the concentration and action of the emulsifiers on

the casein.

Additives

0047Optional ingredients may be added to the processed

cheese blend for economic reasons, or to improve the

shelf-life and quality of processed cheese.

0048Dried skim milk and dried whey Dried skim milk or

whey can be used to replace part of the cheese solids

in the blend for processed cheese food or spread.

Skim-milk powder and whey powder promote the

creaming process and improve spreadability, but the

amount must not exceed 10% of the blend in order to

avoid a sweet-salty taste, especially when young

cheese is used and to prevent browning and crystal-

lization owing to excess lactose in the processed

cheese.

0049Fats Different fats may be added to the blend to

increase the fat-in-dry-matter content of the pro-

cessed cheese. High-fat cream, butter or butter oil

may be used as a source of fat. For processed cheese

tbl0002 Table 2 Suggested blends of natural cheeses for producing

processed cheeses

Processedcheese types Natural cheese (%)

Young Medium-ripened Fully ripened

Block 50–60 20–30 10–20

Processed cheese foods 30–40 50–60 10

Spread 50–60 30–40 10

tbl0003Table 3 Some emulsifying salts used in processed cheese

Type pH (1% solution)

Monosodium citrate 3.75

Trisodium citrate 8.55

Monosodium phosphate 4.5

Disodium phosphate 8.9–9.1

Trisodium phosphate 11.9

Disodium pyrophosphate 4–4.5

Trisodium pyrophosphate 6.7–7.5

Tetrasodium polyphosphate 10.2–10.4

Tetrasodium polyphosphate 9.0–9.5

Sodium hexametaphosphate 6.0–7.5

CHEESES/Processed Cheese 1111

spread of defined total solids, increasing the fat con-

tent causes a decrease in the solids-nonfat (SNF) in

the blend; hence, young cheese with a high intact

casein should be used as the main base to give a stable

emulsion; caseinates may also be used. The emulsify-

ing salts used in processed cheese have no direct effect

on the fat. (See Fats: Uses in the Food Industry.)

0050 Precooked cheese Precooked cheese may be used to

improve the stability of processed cheese. It is nor-

mally produced at peak times of cheese production

when the volume of cheese exceeds the capacity of the

ripening rooms, or when the cheese is not fit for

maturation. Precooked cheese made from young

cheese has a long structure and can be added to a

processed cheese blend containing overripened cheese

to improve its stability. Precooked cheese made from

mature cheese has a short structure and can be used to

promote the creaming property of a processed cheese

spread. The amount of precooked cheese added to a

blend varies according to the degree of maturity of the

cheese in the blend and the type of processed cheese to

be manufactured.

0051 Flavoring materials Flavoring materials may be

added to give a particular flavor to the processed

cheese, or to improve the flavor, especially when

young cheese is used. Among these materials, meat,

ham, wine, fruit, spices, and essences are commonly

used in processed cheese. Flavoring materials should

be of good microbiological quality, and this can be

attained by thermal treatment before addition to

the blend. The physical properties of the processed

cheese are not affected by the use of such additives.

(See Flavor (Flavour) Compounds: Structures and

Characteristics.)

0052 Binding agents Binding agents or stabilizers are

sometimes added to processed cheese spread to

absorb some of the water and improve the stability

of the cheese. The amount of stabilizers, if permitted,

should not exceed 0.8% of the processed cheese. Gum

arabic, locust bean gum, gelatin, pectin, carboxy-

methyl cellulose, and agar are examples of such

materials. (See Stabilizers: Types and Function; Ap-

plications.)

0053 Preservatives The addition of preservatives to pro-

cessed cheese is prohibited in many countries. How-

ever, preservatives such as benzoic and sorbic acids

are used to overcome the blowing of processed

cheese. In addition, biological substances, such as

nisin, are used as inhibitory agents to prevent the

growth of anaerobic spore-formers (Clostridium),

the main cause of blowing in processed cheese.

Nisin is a polypeptide produced by cultures of

some strains of Lactococcus lactis, and is produced

commercially in powder form. Although nisin is used

successfully in many processed-cheese factories, there

is some doubt concerning its efficiency against some

strains of Clostridium.(See Preservation of Food.)

Manufacture of Processed Cheese

0054The steps involved in the manufacture of processed

cheese can be summarized as follows.

Selection and Calculation of the Raw Materials

0055Two important factors must be considered in

selecting the cheese for the blend: (1) the characteris-

tics of the natural cheese, i.e., type, age, maturity, pH,

fat, total solids, and the physical properties; (2) the

desired properties for the processed cheese, i.e., firm-

ness and spreadability.

0056The amount of cheese and other ingredients in the

blend are calculated according to their fat and dry-

matter contents, so that the product conforms to the

legal standards of the specific type of processed

cheese.

Cleaning

0057Hard and semihard cheeses selected for processing

are subject to cleaning before use. Very hard rind,

waxes, or wrapping materials used to cover rindless

cheeses and surface defects must be removed manu-

ally or mechanically before processing.

Cutting, Mincing, and Milling

0058The selected blocks of cheese are cut manually, or

mechanically with special knives, into small slices

suitable for the mincing machines. The slices are

then minced or shredded through special mincing

machines into fine granules, which are ground

through roller mills to make them soft, smooth, and

free from small, hard particles. Mincing and milling

of the cheese enable the emulsifying salts to be in

contact with the cheese, and facilitate the absorption

of water and dispersion of the cheese protein.

Processing

0059Milled cheese and other ingredients of the blend are

placed in the processing kettle. Heating may be

carried out directly by steam injection, indirectly, or

by both methods to a temperature normally not less

than 75



C to insure complete pasteurization of the

processed cheese. Agitation during processing is im-

portant for the complete emulsification of the cheese

blend. Processing kettles are operated either batch-

wise or continuously. They are available in various

1112 CHEESES/Processed Cheese

shapes and capacities. A normal kettle consists of two

pans equipped with one movable cover which bears

an agitator, steam injection nozzles, vacuum tubes,

and gages for temperature and pressure. While pro-

cessing is carried out in one of the pans, the other one

is loaded with raw materials ready for processing.

0060 The temperature and duration of processing are

determined by the type of processed cheese and by

the condition of natural cheese in the blend. In gen-

eral, a period of 2–4 min is required to reach the

processing temperature, and the temperature is kept

constant for a further 5–10 min. Processed cheese

spread is processed at 80–85



C for 8–10 min while

block-processed cheese is processed at 85–95



for 8–15 min in a traditional kettle. The duration of

processing is related to the speed of agitation. Stephan

kettles are equipped with very fast agitators, so

that a period of 4–5 min is sufficient for processed

cheese spread. In modern continuous processed

cheese-making, the processing is carried out in hori-

zontal or vertical tubes in which the blend is heated

by direct steam to 135–145



C for a few seconds.

Homogenization

0061 Homogenization is an optional operation used for

processed cheese spreads, especially those with a

high fat content, and is conducted directly after pro-

cessing. It improves the consistency, stability, and

appearance of the processed cheese. Contamination

during homogenization should be avoided.

Packaging

0062 The hot, flowing mass of processed cheese is trans-

ported manually in stainless-steel buckets or by

special pumps to the filling machines. Keeping the

processed cheese quite hot in the filling machines

eases the sealing of the packaging materials. Pro-

cessed cheese is packed in thin aluminum foil coated

with a special lacquer, in plastic membranes, or in

tins; it is packed in different shapes in amounts vary-

ing from 13 g to 3 kg.

Storage

0063 Directly after packing, the processed cheese is still

quite warm (40–60



C), but it should be cooled to

room temperature in a time that varies according to

the type of processed cheese. As a rule, processed

cheese spread should be cooled quickly (30–60 min)

to prevent the creaming phenomenon; otherwise,

overcreaming will cause fat and water separation

and a defective texture. In cooling processed cheese

spread, a space should be left between the boxes

to facilitate the movement of cool air. For block-

processed cheese, a long time (10–15 h) is needed to

cool it down, but the slow cooling, especially in the

presence of lactose, may result in browning or

firming-up of the cheese, and may allow the growth

of spore-forming microorganisms. After the cheese

has been cooled, it should be kept in a cold store

(5–10



C). It is advisable to keep processed cheese

above 0



C – to prevent the freezing of the product –

and below 20



C; otherwise, surviving microorgan-

isms, especially Clostridium, may grow and cause

defects. (See Spoilage: Molds in Spoilage.)

Defects in Processed Cheese

0064The two main defects in processed cheese are micro-

biological defects and those of physicochemical

origin.

Microbiological Defects

0065Microbiological defects are mainly related to the

blowing of the processed cheese as a result of gas

formation by anaerobic spore-formers (Clostridium).

Spongy texture and bad odor are indicators of a heavy

contamination with Clostridium.

0066In addition, molds may grow on the surface of

poorly sealed packs of processed cheese. However,

proper processing and the addition of permitted anti-

microbial materials should minimize or eliminate

these defects.

Defects of Physicochemical Origin

0067Too firm a block results from one or more of the

following:

0068low moisture content

0069high casein content

0070use of the wrong emulsifiers

0071strong overcreaming

0072low pH

Too soft a block may occur as a result of:

0073high moisture content

0074unsuitable or insufficient emulsifiers

0075too high pH

0076excessive processing

0077addition of milk or whey powder

0078use of too much mature cheese

Inhomogeneous cheese could be the result of:

0079insufficient milling, especially of cheese with a hard

rind

0080improper processing time, temperature, or agita-

tion

0081unsuitable or insufficient emulsifiers

0082use of raw materials of too low pH, particularly an

acid-precipitated cheese or curd

CHEESES/Processed Cheese 1113

Gum-like spread could be caused by:

0083 use of too much young cheese

0084 insufficient processing to achieve proper creaming

0085 absence of creamed, precooked cheese

0086 addition of all the water at one time

‘Sticky spread’ is the term used when the processed

cheese adheres to the aluminum foil. This defect may

be attributable to:

0087 excess water content or all the water added at once

0088 the blend contains too much young cheese

0089 proper creaming is not achieved

0090 no well-creamed, precooked cheese has been

added

0091 the level of intact casein in the blend is insufficient

Reasons for brittle spread are:

0092 overcreaming during processing

0093 addition of too much overcreamed, precooked

cheese

0094 decrease of pH after processing or during storage

0095 Gas formation As result of a chemical reaction be-

tween the aluminum foil and the cheese, the resultant

hydrogen can cause gas ‘holes’ on the cheese surface

without odor formation. This defect can be attributed

to the absence of, or use of poor-quality, lacquering

materials or to the use of an emulsifying salt which is

too acidic or too alkaline.

0096 Browning (Maillard reaction) The normal color of

processed cheese is between white and pale yellow.

Browning may occur directly after processing, or

during storage as a result of a reaction between

amino compounds and reducing sugars. This defect

may be caused by:

0097 Use of too high a processing temperature for a long

time, especially in the presence of lactose.

0098 Storage of the processed cheese at a high tempera-

ture, particularly when the pH is high.

This defect is more common in processed cheese

spread than in block-type cheese. (See Browning:

Nonenzymatic.)

0099 Crystallization Crystallization is a defect which can

be seen inside or on the surface of the cheese; a ‘sandy’

texture may result. The reasons for this defect may be:

0100 precipitation of calcium monophosphate, diphos-

phate, polyphosphate or citrate, particularly when

excess emulsifier has been used

0101 undissolved particles of emulsifier, owing to poor

storage of the emulsifier or improper processing

0102use of precooked cheese with a sandy texture

0103precipitation of lactose crystals as a result of too

much dried milk or whey in the blend

0104use of very mature cheese may result in white pre-

cipitates of some amino acids, such as tyrosine

0105Water separation Water separation can take the

form of small droplets inside the cheese, or wetting

of the cheese surface. It is caused by the following

factors:

0106too low pH of the processed cheese

0107changes in the cheese structure (overcreaming)

0108unsuitable storage conditions, e.g., the cheese is

subjected to mechanical pressure

0109Fat separation Fat separation could be the result of

the following:

0110use of too much mature cheese

0111insufficient or excess emulsifiers

0112too low a pH of the processed cheese

0113storage of the cheese for a long time at a high

temperature

Flavor Defects

0114Examples of the more common flavor defects are:

0115sharp flavors, owing to use of too much mature

cheese

0116flat flavor, owing to use of too much young cheese

0117salty taste, owing to use of salty cheese or excess

emulsifiers

0118putrid taste, owing to use of putrid cheese or the

growth of Clostridium

0119rancid taste, owing to use of rancid cheese and/or

butter, or cheese ripened by molds

0120chemical taste, owing to use of impure emulsifiers,

addition of certain preservatives or stabilizers, or

use of too salty cheese

See also: Browning: Nonenzymatic; Casein and

Caseinates: Uses in the Food Industry; Cheeses: Types

of Cheese; Emulsifiers: Phosphates as Meat Emulsion

Stabilizers; Uses in Processed Foods; Enzymes: Uses in

Food Processing; Fats: Uses in the Food Industry; Flavor

(Flavour) Compounds: Structures and Characteristics;

Lactose; Preservation of Food; Spoilage: Molds in

Spoilage; Stabilizers: Types and Function; Applications;

Vegetable Oils: Types and Properties; Whey and Whey

Powders: Production and Uses

1114 CHEESES/Processed Cheese