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

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strain of P. roqueforti used, water-soluble N in Blue

cheese may be as high as 50% of the total N after

3 months of ripening.

0025 A summary of the sequence of proteolytic events

that occurs in cheese during ripening is shown below.

1. Casein

2. Large peptides

Medium peptides

Small peptides

3. Oligopeptides

Dipeptides

Tripeptides

Rennet, plasmin, and

other proteinases

Large + medium +

small peptides

Starter and

nonstarter

proteinases

Starter and

nonstarter

peptidases

Small oligopeptides

Tripeptides,

dipeptides

Amino acids

Breakdown of Amino Acids

0029 Amino acids can be converted into various products

during the ripening of cheese. Amino acids can be

decarboxylated to CO

and an amine; the resulting

amine undergoes oxidative deamination to give NH

and an aldehyde from which a primary alcohol or

acid is formed. An aldehyde can also be formed by

oxidative deamination of an amino acid. For

example, deamination of glycine and alanine pro-

duces methanol and ethanol, respectively; decarbox-

ylation of tyrosine and histidine results in tyramine

and histamine, respectively. Amino acids can be con-

verted to other amino acids by transamination.

Sulfur-containing amino acids such as methionine

can be converted to products such as methanethiol

(CH

SH), dimethysulfide, etc. Methanethiol and H

contribute to Cheddar cheese flavor. Trytophan can

be degraded to indole, pyruvic acid, and NH

. Tyro-

sine can be degraded to phenol.

Lipolysis

0030 The action of lipase on triglycerides produces fatty

acid(s), monoglycerides, and diglycerides. Lipolysis in

cheese is due to the activities of milk lipoprotein

lipase, exogenous lipases (from rennet pastes), or

lipases from microflora in cheese milk. In pasteurized

milk cheeses, the activity of milk lipoprotein lipase

is small, as under normal pasteurization conditions,

10–15% of the activity in raw milk is left. Some

starter and nonstarter bacteria contain lipases that

hydrolyze mono- and diglycerides but have a weak

lipolytic activity towards unhydrolyzed milk fat

(triglycerides). Therefore, the concentration of free

to C

) fatty acids (FFA) in bacteria-ripened

cheeses like Cheddar, Emmental-type, and Dutch-

type cheeses is low (0.1% in 3-month-old Cheddar,

increasing to < 0.2% after 12 months of ripening).

Cheddar cheese containing > 0.2% FFA usually has

a rancid flavor.

0031In some Italian cheese varieties (e.g., Romano, Par-

mesan and Provolone) lipolysis is more than threefold

greater than that in Cheddar as exogenous lipases are

added during cheese making. The level of lipolysis in

blue-veined cheeses (e.g., Blue, Roquefort, Gorgon-

zola, and Stilton) is high and is due to the activity of

one (the acid enzyme) of the two (acid or neutral)

types of lipases produced by P. roqueforti.

0032The sequential process of catabolism of fat during

cheese ripening is as follows:

0033Liberation of FFA, mono- and diglycerides from

milk fat by lipase.

0034Oxidation of FFA to b-keto acids (b-oxidation).

0035Decarboxylation of b-keto acids to produce

methyl ketones (e.g., acetone from butyric acid).

0036Reduction of methyl ketones to secondary alco-

hols (e.g., reduction of acetone to 2-propanol).

Other lipolytic reactions include formations of esters

by esterases (e.g., esters of alcohol, methional, and

phenol), formation of lactones from unsaturated fatty

acids, and the formation of oct-1-en-3-ol from esters

of linoleic acid or arachidonic acid. The short-chain

–C

) fatty acids, methyl ketones (mostly 2-hepta-

none, followed by 2-nonanone and 2-pentanone),

and secondary alcohols contribute to the characteris-

tic flavor and aroma of cheese.

See also: Amino Acids: Metabolism; Cheeses: Starter

Cultures Employed in Cheese-making; Dutch-type

Cheeses; Lactic Acid Bacteria

Further Reading

Andrews AT and Varley J (eds) (1994) Biochemistry of Milk

Products. Cambridge: Royal Society of Chemistry.

Farkye NY and Fox PF (1990) Objective indices of cheese

ripening. Trends in Food Science and Technology 1:

37–40.

Fox PF (ed.) (1993) Cheese: Chemistry, Physics and Micro-

biology, 2nd edn. London: Elsevier Applied Science.

Fox PF, Lucey JA and Cogan TM (1990) Glycolysis

and related reactions during cheese manufacture and

ripening. Critical Reviews in Food Science and Nutrition

29: 237–253.

Robinson RK (ed.) (1990) Dairy Microbiology, vol. 2,

2nd edn. London: Elsevier Applied Science.

Wong NP, Jenness R, Keeney M and Marth EH (eds) (1988)

Fundamentals of Dairy Chemistry. New York: Van Nos-

trand Reinhold.

1066 CHEESES/Chemistry and Microbiology of Maturation

Manufacture of Extra-hard

Cheeses

V Bottazzi, Universita Cattolica del Sacro Cuore,

Piacenza, Italy

This article is reproduced from Encyclopaedia of Food Science,

Classification, Definition, and Examples

0001 The extra-hard (or very hard) cheeses are a group of

varieties characterized by a long ripening time, and by

the production in large pieces weighing from 18 kg

to more than 100 kg per whole cheese; they are

produced principally in Mediterranean Europe with

sheeps’ or cows,’ milk. Grana cheese produced in the

Po Valley can have the mark ‘Parmigiano Reggiano’

or ‘Gran Padano,’ depending on the areas of produc-

tion. The technology of production is thousands of

years old, and the hard cheeses are characterized by

having a low moisture content. (See Sheep: Milk.)

0002 Once they are ripe, their taste can be harsh and

strong or delicate and fragrant, their structure is com-

pact and friable, and they are used mainly for grating

as a condiment. They play an important role in the

Mediterranean diet.

0003 The following cheeses are included in the group of

extra-hard (or very hard) cheeses: Grana, Pecorino

Romano, Provolone Piccante and Caciocavallo, Sap-

sagno, and Spalen.

0004 Each grana (whole cheese) weighs 34–38 kg, and it

is produced only in northern Italy (Po Valley) using

partially skimmed cows’ milk. It is the best known

cheese among those used for grating as a condiment

and, in order to maintain all its fragrance, it should be

grated just before use. Annual production is 190 000

tonnes, which means using more than 35% of the

Italian whole-milk production.

0005 Pecorino Romano cheese is one of the most ancient

cheeses: a description of the cheese-making process

dating back to before Christ is available. It is pro-

duced in Sardinia and in the area around Rome, using

only sheeps’ milk coagulated by means of rennet paste

from lambs; whole cheeses range between 16 and

22 kg in weight, and its taste is typically strong.

0006 Provolone Piccante cheese and the Caciocavallo

cheese are typical stirred-curd cheeses, originating

in, and very widespread in, the Mediterranean area.

The large Provolone Piccante cheese is cylindrical and

can weigh up to 100 kg: it is produced with raw milk

and rennet paste from kids, and once ripe, its taste is

sharp, strong, and very pleasant.

0007 As far as the description of the manufacturing tech-

nology, both traditional and modern, of extra-hard

cheeses is concerned, we are going to describe only

that of the grana cheese, as it is the most well

known.

Traditional Methods of Manufacture

0008The traditional method is not very different from

methods used today, for it is a feature of hard cheeses

to apply technological rules that do not vary very

much with the passing of time.

0009Up to about 100 years ago, grana cheese was very

often manufactured in cheese factories designed

following particular rules aimed at obtaining well-

defined goals. Such a factory was a single, isolated

building with an octagonal base, and walls free

from windows. The height of the building was

about 3 m, and the roof was supported by a wooden

structure. Architecturally, such buildings are pleasant

in appearance.

0010Inside, all the cheese-making operations were

carried out using direct-fire heating of the milk, and

the typical structure allowed natural aeration.

0011According to tradition, raw milk obtained the

evening before manufacture was poured into shallow

vats with a large surface area, so as to facilitate sep-

aration of the cream; this process was necessary since

grana cheese is produced with partially skimmed

milk. The vats were made of either wood or tin-plated

copper of sufficient volume to hold half of the milk

necessary to produce a whole grana cheese, i.e., 250 l.

The creaming took place overnight, and in the morn-

ing, after the skimming operation, the milk was

mixed with fresh milk, and cheese manufacture in a

large copper vat commenced.

0012Until the end of the nineteenth century, no starter

cultures were added, and in order to reach the desired

acidity, the contaminating microflora acquired during

milking and in the cheesemaking operation was

exploited; the vat was then left for a prolonged

period, which allowed a remarkable bacterial flora

to develop. (See Starter Cultures.)

0013Rennet prepared from the stomach of sucking

calves was always used to coagulate the milk. After

breaking the coagulum, very small curd granules,

which had a very low moisture content, were

obtained. The granules were smaller in dimension

than rice grains, and the expulsion of whey was

through the high ‘cooking’ temperature (53–54



C).

0014Originally, the cheese vat had a capacity of 500 l (so

as to produce one cheese at a time), had a truncated

cone shape (inverted bell), was made of copper, and

had direct-fire heating.

0015Salting, using brine, was started 2 or 3 days after

production and continued for 25–28 days in separate

brining rooms.

CHEESES/Manufacture of Extra-hard Cheeses 1067

0016 The ripened cheeses were carried out in stores at

the prevailing temperature, i.e., under the influence of

the seasons, temperatures varied from about 5 to



C, for at least 18 months. During this long period,

and especially during the first months, many manual

operations were necessary in order to avoid the

development of molds on the cheese surfaces, and to

obtain a smooth, even rind. Towards the end of

the ripening period, the cheese was covered with a

mixture of carbon black, umber, and grape seed oil,

so as to produce a black color and a characteristic

shiny, bright appearance.

Modern Systems of Production

0017 The current manufacturing technology of grana

cheese shows, in comparison with the traditional

technology, several differences.

0018 The current procedure uses raw milk, natural

creaming and a high cook temperature, but now-

adays, the technology also includes the addition of

a starter culture, ‘double cheese-making,’ a rapid

cheese-making time, ‘twins’ production, controlled

ripening as well as other changes, which will be

described later.

0019 The whey starter culture was introduced at the end

of the nineteenth century, and has a very complex

microflora composition. The prevailing bacteria are

Lactobacillus helveticus together with Lb. del-

brueckii ssp. lactis and ssp. bulgaricus and Lb. fer-

mentum; thermophilic streptococci are generally

absent. The culture is phage-resistant, has a high

acidifying capacity, is thermophilic, has a very good

viability, and is very easy to prepare. It is affected by

the microbial characteristics of the milk and the en-

vironment where manufacture takes place, and it is

the result of the action of several technological factors

typical of each environment; because of its character-

istics, it turns out to be an unrepeatable culture that

cannot be replaced by the association of different

strains in the laboratory. The activity of the natural

whey culture is very important: primarily to produce

an acid environment in the cheese (thereby inhibiting

gas-producing bacteria), to take part in the hydrolysis

of proteins, as well as to take part in the hydrolysis of

proteins, as well as to take part in taste and fragrance

formation. (See Lactic Acid Bacteria; Whey and

Whey Powders: Production and Uses.)

0020 The ‘double cheese-making’ process involves the

transformation of milk from two milkings, and brings

about the creaming of all the milk employed. From

a practical point of view, this is a very important

change, because by creaming at a temperature of

12–15



C, not only is the milk skimmed, but also

many bacteria are carried out with the cream; an

effect similar to that obtained through pasteurization.

0021This cold reduction in bacterial numbers leaves

the cheese-making properties of raw milk unchanged,

a point of primary importance in grana cheese

production.

0022This system is widespread in the whole product-

ion zone of grana Padano; the grana Parmigiano

Reggiano cheese-makers keep to the traditional

method of manufacture.

0023The ‘rapid cheesemaking time’ used today in grana

cheese production refers to the time between the

addition of rennet to the milk and the end of the

curd cooking. At the end of the nineteenth century,

the time was rather long – sometimes even 50–60 min

– but today, it is just 18–22 min.

0024The reasons for these changes include both the

different conditions of milk production, and the

introduction of thermophilic cultures of lactic acid

bacteria. From a practical point of view, it allows

better work organization and more regular cheese-

quality standards.

0025The ‘twins’ production started with the replace-

ment of the 500-l vats with 1000-l vats; the shape of

the copper vat is unchanged and is typical for this

kind of cheese; the maximum capacity is 1000 l of

milk. As a consequence, two whole cheeses can be

obtained each time, and these are called twins, since

they are the result of the division into two even parts

of the curd obtained from 1000 l of milk.

0026The number of grana cheese factories is still more

than 1100 today, but a progressive transformation

towards medium-to-large factories is taking place.

Several copper vats may be found in one factory, but

because the manufacture involves separate batches of

milk, each of 1000 l, there is neither real mechaniza-

tion nor automation (not even cheese pressing is

carried out mechanically). None the less, the whole

cheese-making process in the vat is carried out in a

short time, with a regular and precise sequence, even

in the case of large factories. Today, the coagulum is

broken first manually, but further breaking up and

stirring of the curds/whey to complete cooking are

carried out using simple mechanical means.

0027Ripening is carried out in stores with controlled

temperature (16–18



C), humidity (85%), and con-

tinuous air change without creating currents of air.

0028The cheese is ripened for 14–24 months (the grana

Padano needs a shorter time than Parmigiano

Reggiano), and during this period, the whole cheeses

are often turned upside down once a week during the

first months, and less frequently thereafter. Mainten-

ance of the cheeses (inverting and brushing) is carried

out mechanically by means of automatic systems.

1068 CHEESES/Manufacture of Extra-hard Cheeses

0029 The modern system for Grana cheese production

provides for milk cooling at 8



C for 12 h in sheds,

then mixing with warm milk from the subsequent

milking, thus allowing a single collection per day. If

necessary, and in particular in areas where there is a

high consumption of ensiled fodder, irregular fermen-

tations can be avoided through the partial elimination

of bacteria by centrifugation. The main steps in

Grana cheese production can be described briefly as

follows:

0030 Milk is poured into 1000-l vats, with dimensions

of 4.50 1.90 0.25 m, for creaming, so that the

milk reaches the copper, truncated cone-shaped

cheese vats with a fat content ranging, depending

on the region, from 2.00 to 2.30%.

0031 After transfer of the partially skimmed milk to the

1000-l copper vats, about 3% of natural whey

culture is added to give an acidity (in lactic acid)

in the mixture (milk þwhey culture) of 0.19–

0.20%; the milk is heated to 33



C and rennet

(titer 1 : 100 000) at a level of 2 g per 100 l.

0032 Coagulation occurs in 9–10 min, and the coagu-

lum is broken for 3 min to obtain curd granules

having the dimensions of rice grains.

0033 The curds/whey are heated to reach the cook

temperature of 54



Cin7–8min.

0034 The curd is allowed to settle and form a compact

layer at the bottom of the vat, and the curd is then

kept in the hot whey for about 45 min.

0035 The bed of curds is divided into two portions, each

of which is scooped from the mold using a coarse

cloth, and placed in the unfixed wooden molds;

at the start of the pressing operation, the cheeses

are pressed by loading each cheese with 20-kg

weights.

0036 During the first 10 h, the cheeses are turned three

or four times, with cloth changes; after 15–20 h,

the cloths are removed, and the wooden mold is

replaced by a metal mold.

0037 On the third day, the cheeses are brine-salted

(density 22



and temperature 16–17



C) for

24–28 days.

0038 At the end of the salting and once the whole

cheeses are dry, they are transferred to the ripening

store and kept at a temperature of 16–18



C and a

humidity of 85%.

Maturation and Storage

0039 Grana cheese, after ripening, has the following

average composition (%):

0040 protein: 33.20

0041 fat: 27.50

0042 ash: 4.80

0043moisture: 32.00

0044sodium chloride: 1.60

0045lactic acid: 1.30

0046Owing to the high content of protein and low fat

content, grana cheese can be defined as a ‘half-fat’

cheese having a high protein content.

0047During the first hours of pressing, an intense

fermentation process occurs in grana cheese, trans-

forming the lactose into lactic acid. After 6 h, the pH

is about 5.50 and after 16 h, 5.0; the lactic acid is

distributed as indicated in Table 1.

0048After 5 h of fermentation, the lactose has decreased

to about 1.6%, the accumulated galactose is slightly

higher than 1%, and the concentration of glucose is

about 0.30%.

0049During the long ripening period, even the casein

undergoes extensive proteolysis. b-Casein is hydro-

lyzed rapidly during the first part of the ripening

cycle, and its enzymatic degradation finishes within

the first 12 months of ripening. However, a

-casein is

degraded much more slowly. With reference to the

total amount of hydrolysis products, about 30% are

from b-casein, while those from a

casein form about

18%.

0050The release of amino acids increases progressively

until about the 15th month of ripening and then

becomes stable. When the cheese is ready to use, the

amino acids form, on average, 22% of the total crude

nitrogen value and 7% of the cheese; as a conse-

quence, grana cheese is one of the cheeses having a

high content of free amino acids. In cheeses of first-

class quality, serine increases progressively through-

out the ripening time and finally reaches about 1.5%

of free amino acids; glutamine reaches 1% in the

first 12 months and disappears once the ripening is

finished, and arginine, released during the ripening

period, is degraded into ornithine. The presence of g-

aminobutyric acid indicates that anomalous fermen-

tation processes have taken place. (See Amino Acids:

Properties and Occurrence.)

0051The hydrolysis of fat in grana cheese does not play

an important role, in spite of the long ripening period.

There is also a slight loss of vitamin A, a greater

remarkable loss of vitamin E, and a serious reduc-

tion of b-carotene from 640 to 100 mg per 100 g of

cheese. (See Carotenoids: Occurrence, Properties, and

tbl0001Table 1 Isomeric distribution of lactic acid with time in a grana

cheese (values are in g

1

)

0h 2h 4h

D() 0.90 D() 2.85 D() 3.99

L(þ) 1.80 L(þ) 4.47 L(þ) 6.35

DL 2.7 DL 7.32 DL 10.34

CHEESES/Manufacture of Extra-hard Cheeses 1069

Determination; Retinol: Properties and Determin-

ation; Tocopherols: Properties and Determination.)

0052 The mineral component, composed of macro- and

microelements, takes on a very precise character: cal-

cium, phosphorus, and magnesium are the elements

present at the highest levels: 1150, 680, and 430 mg

per 100 g respectively. The calcium:phosphorus ratio

is high (1.70), i.e., much higher than that found in

many other cheeses. (See Calcium: Properties and

Determination; Magnesium.)

0053The average content of sodium in grana cheese is

650 mg per 100 g. Among the microelements, the con-

tent of zinc is very high. (See Sodium: Properties and

Determination; Zinc: Properties and Determination.)

fig0001 Figure 1 Calcium phosphate microcrystals in 24-h grana cheese. (A) Microcrystal internal structure during the formation phase.

(B) Microcrystal internal structure at the end of the formation process.

1070 CHEESES/Manufacture of Extra-hard Cheeses

0054 The microbiological composition of grana cheese is

characterized by two separate steps. The first con-

cerns the very young cheese (first hours), and the

second covers the first months, and continues even

until the end of ripening.

0055 The lactic acid bacteria are numerous during the

first period, and the flora is that of the starter, mainly

composed of L. helveticus, usually reaching, after

12–14 h, 0.8–1 10

cells per gram, and L. fermen-

tum, which reaches a maximum in about 24–28 h

with 120–140 10

cells per gram. In this first

period, even L. delbrueckii ssp. bulgaricus and ssp.

lactis are active. The development of this homo- and

heterofermentative thermophilic lactic acid flora

plays a very important role in the commercial success

of the final product, since it:

0056 ensures a rapid acidification of the fresh cheese;

0057 regulates whey drainage;

0058 accumulates enzymes of the proteolytic system;

0059 causes the formation of small holes;

0060 produces volatile compounds;

0061 contributes to the formation of the cheese

structure.

0062 During the second period, a nonstarter lactic acid

flora develops, consisting of coccoid lactic acid

bacteria, e.g., Pediococcus acidilactici and rod-shaped

bacteria, e.g., L. casei ssp. casei, ssp. pseudoplan-

tarum and ssp. rhamnosus.

0063During the period of maximum development, i.e.,

25–40 days after production, this lactic acid flora

reaches 60–80 10

cells per gram, but, for the

remaining ripening period, the number decreases

progressively. Pediococci are the most resistant

forms and are still present in the cheese at the time

of consumption.

0064The metabolic activity of the mesophylic lactic

acid bacteria contributes to the ripening process,

and its contribution to casein hydrolysis is very

important.

0065Finally, there are the propionic bacteria, which are

useful for the development of the organoleptic char-

acteristics of the cheese, so long as their development

is limited to a few million cells per gram.

Formation of Micro- and Macrocrystals

0066The formation of individual or grouped crystals

occurs during ripening of the cheese (Figures 1–3).

In grana cheese, the first type of microcrystals appears

at the end of the lactic fermentation driven by a

thermophilic lactic microflora, during the first hours

of ripening. The crystals are spherical. The external

side is porous, showing an irregular surface, with a

diameter of 8–20 mm. The internal portion, as shown

in Figure 1A, is well defined, with a compact periphe-

rical ring and laminar structure converging in the

centre. Crystal formation is limited to the first 48 h

fig0002 Figure 2 Needle-shaped calcium lactate crystal aggregates in ripened grana cheese.

CHEESES/Manufacture of Extra-hard Cheeses 1071

fig0003 Figure 3 Internal structure of a tyrosine macrocrystal in ripened grana cheese.

fig0004 Figure 4 Sodium chloride microcrystals in ripened grana cheese.

1072 CHEESES/Manufacture of Extra-hard Cheeses

in grana cheese. During further cheese ripening, no

further increase in volume or number of crystals can

be seen. These crystals are composed of calcium

phosphate.

0067 Figure 2 shows a second type of crystal: needle-

shaped and generally grouped. At the end of ripening,

these can be observed in the cheese paste as white,

friable, sandy granules. These crystals are typical of

grana Padano cheese and are generally associated

with a high-quality product (if not too numerous)

and are composed of calcium lactate.

0068 At the end of ripening, a gray crystalline formation

becomes evident (0.3–0.5 mm in diameter). These

crystals are formed by tyrosine and impart a bitter

taste. Their internal part is shown in Figure 3.

Aggregates of NaCl rarely appear in cheese at the

end of the ripening process. Figure 4 shows these

aggregates observed under a scanning electronic

microscope.

Specification and Standards

0069 Grana cheese is a half-fat hard cheese, cooked and

slowly ripened, with a light straw color yellow and a

compact, granular and friable structure with flake-

shaped radial fractures and a fragrant and delicate

aroma. For its production, raw milk, half-skimmed

through natural creaming, is used. To the milk is

added a natural starter culture of thermophilic lactic

acid bacteria developed in whey, and the mixture is

coagulated by means of rennet from sucking calves.

The ripening lasts 18–24 months for Parmigiano

Reggiano and 13–15 months for grana Padano.

0070 The ripe product, ready to eat, has:

0071 a cylindrical form with convex (lateral) sides, and

slightly convex flat sides;

0072 dimensions varying between 35 and 45 cm in di-

ameter, and between 18 and 24 cm in height on the

lateral side;

0073 a whole-cheese weight between 32 and 34 kg;

0074 a hard, smooth, bright surface, with a natural

uniform color.

See also: Amino Acids: Properties and Occurrence;

Calcium: Properties and Determination; Carotenoids:

Occurrence, Properties, and Determination; Lactic Acid

Bacteria; Magnesium; Retinol: Properties and

Determination; Sheep: Milk; Sodium: Properties and

Determination; Starter Cultures; Tocopherols:

Properties and Determination; Whey and Whey

Powders: Production and Uses; Zinc: Properties and

Determination

Further Reading

Bosi F, Bottazzi V, Vescovlo M et al. (1990) Batteri lattici

per la produzione di formaggio grana. I parte: caratter-

izzazione tecnologica di ceppi di lattobacilli termofili.

Scienza e tecnica Lattiero Casearia 41: 105–136.

Bottazzi V (1979) Microbiologia del Fermenti Lattici.

Modena: Aitel.

Fortina MG, Parini C, Manachini PG et al. (1990)

Genotypic and phenotypic correlationships among

some strains of Lactobacillus helveticus. Biotechnology

Letters 12(10): 765–770.

Parisi O (1958) Il Formaggio Grana. Mucchi, Modena:

Stem.

Various authors (1979a) Il formaggio grana. Tomo 1.

Latteria Didattica P. Marconi, Thiene (VI).

Various authors (1979b) Il formaggio grana. Tomo 2.

Latteria Didattica P, Marconi, Thiene (VI).

Various authors (1988) Atti giornata di studio ‘Ricerca

triennale sulla composizione e su alcune peculiari carat-

teristiche del formaggio Parmigiano Reggiano’. Reggio

Emilia 28 marzo 1988. Consorzio del Formaggio Parmi-

giano Reggiano.

Manufacture of Hard and

Semi-hard Varieties of Cheese

P F Fox and P L H McSweeney, University College,

Cork, Ireland

Background

0001Approximately 500 varieties of cheese are recognized

by the International Dairy Federation; in addition,

numerous minor cheese varieties are manufactured

locally. For various reasons, a number of attempts

have been made to classify cheese varieties into mean-

ingful groups. Traditional classification schemes have

been based principally on moisture content, i.e.,

extra-hard, hard, semihard/semisoft, or soft. Al-

though used widely, this scheme suffers from serious

limitations, since it groups cheeses with widely differ-

ent characteristics, e.g., Cheddar and Emmental are

classified as hard cheeses, although they have quite

different textures and flavors, they are manufactured

by very different technologies, and their microbiology

and biochemistry are very different. This compos-

ition-based scheme is made more discriminating by

including information on the source of the milk, co-

agulant, principal ripening microorganisms, and cook

temperature. Based on the method of milk coagula-

tion, cheeses may be divided into four super-families:

CHEESES/Manufacture of Hard and Semi-hard Varieties of Cheese 1073

.0002 rennet-coagulated cheeses: most major cheese

varieties;

0003 acid-coagulated cheeses, e.g., Cottage, Quarg,

Cream;

0004 heat/acid-coagulated, e.g., Ricotta;

0005 concentration/crystallization, e.g., Mysost.

0006 Rennet-coagulated cheeses represent * 75% of

the total world production and include all ripened

varieties; owing to the great diversity of these cheeses,

further classification is desirable, e.g., based on the

characteristic ripening agent(s), e.g., internal bac-

teria, internal mold, surface mold or surface smear

(bacteria), or manufacturing technology. The most

diverse family of rennet-coagulated cheeses is that

containing the internal bacterially ripened varieties,

which include most hard and semihard cheeses. The

composition of these cheeses is not defined precisely,

and for the present purpose, cheese containing about

35–45% moisture will be included. Traditionally,

cheeses develop a rind through which moisture evap-

orates; hence, the composition of cheese changes as it

ages, and there is a moisture gradient from the surface

to the center. The moisture content of long-ripened

cheese may decrease by 5–10% during ripening. Ob-

viously, the differentiation between hard and semi-

hard is arbitrary.

Hard Varieties

0007 Several subgroups of hard/semihard cheeses are dis-

cussed in other articles, i.e., Swiss-type, Dutch-type,

pasta filata, and ripened-in-brine varieties. This

article will focus on Cheddar-type cheese with brief

descriptions of British Territorial cheeses and several

other varieties which are generally similar to the

above.

Cheddar-type Cheese

0008 Hard cheeses have a moisture content of 35–40% and

are manufactured by a generally similar technology,

including renneting at * 30



C, cutting the coagulum

into small pieces, cooking to * 40



C, drainage of the

whey and pressing the curd. In some cases, e.g., Ched-

dar and other British varieties, the curds are textured

in the vat (‘cheddared’), and the blocks of curd are

milled and dry-salted when sufficient acidity has

developed. The salted curds are molded, pressed for

12–16 h, and matured for 3–12 months, or longer.

Hard cheeses include Cheddar, Cheshire, Derby,

Gloucester, and Leicester (British), Cantal (French),

Friesian and Leiden (Netherlands), Graviera and

Kefalotiri (Greece), Manchego, Idiazabal, Roncal,

and Serena (Spain), Sa

o Jorge (Azores, Portugal),

and Ras (Egypt).

0009Cheddar cheese, which originated around the vil-

lage of Cheddar, Somerset, England, is one of the

most important cheese varieties worldwide, re-

presenting * 30% of total cheese production; it is

produced on a large scale in the USA, the UK, Austra-

lia, New Zealand, Canada, and Ireland. Although

small amounts of Cheddar cheese are made from

raw milk, mainly at the farmhouse level, the vast

majority is produced from pasteurized cows’ milk

standardized to a casein:fat ratio of * 0.7:1, intended

to give a fat-in-dry matter (FDM) of at least 48%.

With the objective of reducing the intake of dietary

fat, reduced-fat Cheddar is produced commercially,

but because its flavor and especially its texture (which

is hard and crumbly) are inferior to those of full-fat

Cheddar, it has only a minor share, perhaps 5%, of

the market. However, research is continuing on ways

of improving the flavor and texture of reduced-fat

Cheddar and related varieties.

0010Some consumers prefer an intensely colored cheese,

and the orange pigment, annatto (E160b), is some-

times added to the milk for Cheddar and other British

cheeses. Annato is produced from the berries of the

tropical plant, Bixa orellana, and contains two

apocarotenoid pigments, bixin and norbixin.

0011A key feature of the manufacture of all cheeses is a

decrease in pH to * 5, usually through the produc-

tion of lactic acid in the curd. Traditionally, the lactic

acid was produced by the adventitious microflora,

especially lactic acid bacteria (LAB), but this was

very variable and unpredictable, and hence the rate

of acidification varied, with adverse effects on the

quality of the cheese. The practice of adding a culture

of selected LAB, referred to as a starter, was intro-

duced at the end of the nineteenth century, and it is

now standard practise to inoculate milk for Cheddar-

type cheese with a culture of mesophilic LAB, i.e.,

Lactococcus lactis ssp. cremoris and/or Lc. lactis

ssp. lactis. Initially, these cultures were undefined

and contained a mixture of strains. Defined-strain

starters were introduced in New Zealand in the

1930s, initially as a component of a phage-control

program, and are now used widely in large Cheddar

factories; their main attraction is that, if properly

managed, they give a very reproducible rate of

acid production and hence cheese quality, although

the flavor of the cheese may be rather mild, due to the

lack of microbial enzyme diversity. Today, the

thermophilic organism, Streptococcus thermophilus,

is fairly widely used as a component of starters for

Cheddar cheese, mainly to increase stability to phage,

to permit a higher cook temperature, and to intensify

and modify the flavor of the cheese.

0012Sufficient rennet is added to the milk at * 30



Cto

give a firm coagulum after about 35 min. Traditionally,

1074 CHEESES/Manufacture of Hard and Semi-hard Varieties of Cheese

rennet prepared by extracting the stomachs of young,

milk-fed calves with NaCl brine was used

for Cheddar, but owing to increased production of

cheese and a dwindling supply of young calves,

several rennet substitutes have been introduced over

the past 40 years, especially bovine and porcine

pepsins, acid proteinases from Rhizomucor meihei,

R. pusillus, and Cryphonectria parasitica and chymo-

sin from genetically engineered microorganisms. An

aqueous extract of the flowers of the cardoon thistle,

Cynara cardunculus L., which is used in Portugal for

the manufacture of Sera da Estre

la, is used in the

western parts of Spain for the manufacture of Serena,

a hard cheese.

0013 When the coagulum is sufficiently firm, it is cut

into cubes of about 1 cm. A rennet-induced milk gel

is quite stable if left undisturbed, but if cut or broken,

the pieces of curd contract (synerese), expelling whey.

By controlling the rate and extent of syneresis, the

cheese-maker can control the composition of the

cheese curd and hence the rate and direction of

ripening and the quality and stability of the cheese.

Syneresis is promoted by increasing the temperature,

reducing the pH or agitating the curds/whey. In the

case of Cheddar and related cheeses, the curds/whey

mixture is cooked from 30 to 37–39



C over 30 min

and held at this temperature for about 1 h. At this

stage, the pH should be * 6.1, and the whey is

drained off; if the pH has not decreased sufficiently,

removal of the whey may be delayed. The curds for

Cheddar and related varieties are ‘cheddared,’ apro-

cess unique to, and characteristic of, these varieties.

The traditional cheddaring process involves forming

the drained curds into beds at both sides of the vat,

separated by a trough for whey drainage. After about

15 min, the beds of curd are cut into blocks, which are

inverted and piled at intervals. The cheddaring pro-

cess allows time for acidity to develop in the curd

(from c. pH 6.1 to 5.4) and subjects the curds to

gentle pressure, which assists in whey drainage and

causes the blocks of curd to flow and spread. During

cheddaring, the curd granules fuse, and the texture

becomes similar to that of cooked chicken-breast

meat at the end of cheddaring. This textural change

was considered to be the characteristic feature of

Cheddar cheese manufacture, but the principal func-

tion of cheddaring is to promote curd syneresis and to

allow development of sufficient acid as a result of

which colloidal calcium phosphate dissolves, leaches

out of the curd, and is lost in the whey. The calcium:-

casein ratio has a major effect on the textural proper-

ties of cheese, including stretchability, pliability, and

meltability; these features are particularly important

in Cheddar and pasta filata cheeses.

0014When the pH reaches c. 5.4, the curd blocks are

milled into chips and salted at a level of * 3%, to

give * 2% salt in the finished cheese. The salted

curds are ‘mellowed,’ during which the salt dissolves

in moisture on the surface of the chips. Mellowing

is critical for the proper control of the concen-

tration and distribution of salt in the cheese. The

curds are then molded, traditionally as 10–40 kg

cylinders (typically, 20 kg), and pressed overnight at

* 200 kN m

2

. Cheddar cheese curd is matured at

6–12



C for a period ranging from 3 to 24, or more,

months, depending on the maturity desired. Trad-

itionally, the wheels of Cheddar were dried slowly

to form a rind and then dipped in yellow or black

wax.

0015Although the traditional manufacturing process

described above, and summarized in Figure 1, is still

practiced in small factories and on a farmhouse scale,

most Cheddar cheese is now manufactured in large

(20–50 000 tonnes per annum), highly automated

factories (e.g., Figure 2). The principal features of

automated Cheddar production include the use of

large (30 000 l) enclosed vats in which cheese-making

commences at 30 min intervals to provide a semi-

continuous supply of curd. All operations in the vat

(addition and mixing of starter and rennet, cutting of

the gel, and cooking of the curds) are automated and

computer-controlled. After cooking, the curds/whey

mixture is pumped on to an inclined screen, on which

the curds and whey are separated. The drained curds

are moved pneumatically to a tower, c. 5 m high, or to

a belt system on which restricted flow and slight

pressing occurs. The pH of the curds should have

decreased to * 5.4 as they exit the tower or belt.

Since it is not possible in large automated factories

to hold the curds until the pH decreases to 5.4, con-

sistent production of acid is critical and is one of the

principal advantages of using defined-strain highly

selected starters.

0016Large blocks of curd are sliced off the body of curd

as it exits the tower or belt and are milled and salted

automatically on a belt system. The salted curds are

conveyed pneumatically to the top of a ‘block

former,’ a large tower in which the salted curds are

compressed by their own weight and subjected to a

slight vacuum. As the curds exit the block former,

after * 30 min, 20-kg blocks are cut off by a guillo-

tine, vacuum-packaged in plastic bags, placed in card-

board boxes, stacked on a pallet (usually 1 tonne per

pallet), and transferred to ripening rooms. In many

large factories, the boxed cheeses are cooled rapidly

in a forced-air cooling tunnel before palleting; the

objective is to retard the growth of nonstarter LAB,

which may cause defects in flavor and texture.

CHEESES/Manufacture of Hard and Semi-hard Varieties of Cheese 1075