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would be common contaminants from the environ-

ment. The soured milk was too precious to be dis-

posed, leading to an acquired taste for this product.

Handling of the clotted milk caused separation of

a serum (whey) and yielded the first acid coagulated

cheeses (See Cheeses: Soft and Special Varieties;

Quarg and Fromage Frais). The practice of storing

and transporting milk in animal skins, including

stomachs, also clotted the milk by enzymes such as

chymosin and pepsin that leached from the stomach

lining, which yielded a gel that differed in character-

istics from the acid-coagulated curd (See Cheeses:

Chemistry of Gel Formation). Jostling in the bag

caused separation of whey that yielded curd, the pre-

cursor of a wide range of enzyme (rennet)-clotted

cheeses.

0004 The release of the whey from the curd and the

hardening of the cheese probably prompted the

existing artisans to further dehydrate the curd by

techniques similar to the primitive practices used for

air-drying of meats. Curds produced by the action of

the stomach enzymes were more conducive to dehy-

dration, which greatly extended the storage and

transportation of these cheese types.

0005 The evolution of using sodium chloride and heat

to preserve various foods was applied to the acid-

and rennet-coagulated curds and created more diver-

sity in the characteristics of cheeses that were given

unique names. Modern cheese varieties such as

highly salted Feta and Domiati cheeses (See Cheeses:

White Brined Varieties) and the heat-plasticized Pro-

volone and Mozzarella cheeses are examples of this

evolution.

0006 Travel and trade introduced cheeses with other

valued goods to widespread regions and cultures.

Introduction of cheeses into different climatic condi-

tions altered the type of microorganisms and their

rate of growth in the cheese curd and, consequently,

the characteristics of the resulting cheeses. Lower

temperatures minimized the need for high sodium

chloride levels and use of higher heat treatments as

means of preservation. The requirement for low

moisture contents was also lessened. Artisans in

Central Europe undoubtedly recognized that cooler

temperatures in the spring and autumn yielded

cheeses of better quality. They also would have

known about cool caves in their localities and started

the practice of storing cheese in caves or in cooler

areas of their dwellings. Under these conditions that

imposed fairly consistent temperature and humidity,

various proportions of fungal and bacterial growth

occurred that imparted unique and desired character-

istics. Surface-ripened cheeses such as Camembert,

Roquefort, and Munster are current varieties that

evolved from such conditions (See Cheeses: Surface

Mold-Ripened Cheese Varieties). Artisans in the

mountainous areas of Europe, bordering on Mediter-

ranean regions, would have been familar with cheese

varieties that were subjected to a higher temperature

during manufacturing. Storing such cheeses or deriva-

tives of such cheeses at lower mountainous tempera-

tures and with an accidental or deliberate reduction

of the sodium chloride content would promote the

growth of eye-forming bacteria, resulting in present-

day Swiss-type cheeses (See Cheeses: Cheeses with

‘Eyes’).

0007The evolution of varietal cheese development has

been, and still is, a continuous process. Varieties

introduced within the past century have generally

been variants of recognized cheese varieties. None of

the existing major cheese varieties was the result of

deliberate responses to consumer demands and by

technologies developed specifically to achieve the

consumer-driven demand. All were the results of ac-

cidental geneses and subsequent derivations. Science

and technology have been vital in optimizing the

quality, uniformity, and ability to modify defined

characteristics either within the variety or to

produce derivatives of the original variety (See Chem-

istry of Gel Formation; Cheeses: Chemistry and

Microbiology of Maturation). Science and tech-

nology will become increasingly important in con-

trolling the functional characteristics of cheeses

in the future. Traditional cheese varieties will be

altered to attain unique flavors and physical proper-

ties that will differ substantially from the original

variety. These derived types are used as food ingredi-

ents to enhance and modify the food, to which the

cheeses are added, a trend that will increase in the

future.

Classification of Cheese

0008Cheese technologists and merchandizers of cheese

have attempted to categorize cheeses based upon vari-

ous criteria. Segregating cheeses by national origins

may be useful for marketing purposes, but this ap-

proach has few technological bases for categoriza-

tion, and the production of a given variety may be

globally dispersed. A good example is Cheddar cheese,

which originated in England, but now, more is pro-

duced in North America and in Oceania than the

country of origin. Similarly, production of Swiss

cheese and surface-ripened French cheeses occurs

throughout the world.

0009Scientists and technologists have generally categor-

ized cheeses based upon composition, manufacturing

methods, and systems for maturing or aging cheese.

One scheme differentiates varieties by the type of

microbial primary and secondary starters (See

1046 CHEESES/Types of Cheese

Cheeses: Starter Cultures Employed in Cheese-

making) used in manufacturing and maturation

of cheeses and by the moisture content or, more spe-

cifically, the ratio of moisture to protein in cheeses.

This scheme would differentiate cheeses on the basis

of flavor and physical characteristics but would in-

clude only natural cheeses, which are generally de-

fined as those varieties derived from milk or milk

components. A similar approach suggested that

there were only 18 distinct types of natural cheeses

that could be categorized into eight families based on

firmness of the varieties and the method of matur-

ation (Table 1).

0010 Slightly more comprehensive classifications differ-

entiated varieties by composition, firmness, and mat-

uration/flavoring agents (Table 2)orby

manufacturing and maturation processes (Table 3).

The system used in Table 2 expands the differenti-

ation of natural cheeses, includes cheeses made from

whey and introduces a new category of cheeses that

attribute their dominant flavor to added spices

or ingredients. Cheese types are divided into two

major categories, natural and process cheeses, and

the natural cheeses are divided into those in which

the curd is formed either by acid or by enzymes in

Table 3. This classification introduces the category of

process cheeses, which are produced by heating and

melting natural cheeses with the aid of calcium-che-

lating emulsifying salts (See Cheeses: Processed

Cheese).

0011 The previous classification systems were inte-

grated into a comprehensive categorization shown

in Figure 1. Although process cheeses are not

included, a detailed differentiation of natural cheeses

based upon methods of clotting milk, maturation

agents, and composition gives a good overview of

the diversity of cheeses. There is also merit in the

initial division into four ‘superfamilies’ based upon

differences in curd formation. The method of coagu-

lating milk or milk components (curd formation)

yields distinctly different end products because of

the chemistry of the coagulum (See Cheeses: Chemis-

try of Gel Formation). Although there is heterogen-

eity within the families of cheeses formed by acid

coagulation, heat/acid coagulation, and concentra-

tion/crystallization, these differences are less than

those between families. The most diverse family con-

tains cheeses formed by rennet coagulation. Dividing

this family into classes based on the location and

major types of microorganisms that distinguish the

classes is useful from technological and marketing

standpoints. The most diverse category is the

surface-ripened cheeses that have a heterogeneous

surface flora that can include molds. However, these

cheeses are distinct from the surface mold-ripened

cheeses. The major cheese varieties, in terms of

breadth of type and of amounts produced, are

included in the internal bacterially ripened cheese

category. The extra-hard, hard, and semihard cheeses

vary in moisture contents (moisture:protein ratios)

but are similar in containing a mixture of bacteria

within the cheese to create the flavors and desired

maturity of the particular type (See Cheeses: Manu-

facture of Extra-hard Cheeses; Manufacture of Hard

and Semi-hard Varieties of Cheese). The extra-hard

types are generally distinguished by high numbers of

heat-tolerant lactic acid-producing bacteria that

evolved from the practice of heating the curd and

whey to high temperatures during manufacturing.

The severe heat treatments were not used in the

manufacturing of the hard and semihard types,

resulting in higher moisture contents; different types

of lactic-acid producing bacteria dominating the flora

of such cheeses during manufacturing and early stages

of maturation (See Cheeses: Starter Cultures

Employed in Cheese-making). These same effects of

heat treatments resulted in two classes of cheese with

eyes. Higher temperatures and lower concentrations

of salt promoted the heat-tolerant lactic bacteria plus

the eye-forming propionibacteria in Swiss-type

cheeses. Lower temperatures during manufacturing

and early maturation of Dutch-type cheeses created

the environment for the mesophilic lactic bacteria and

lactic bacteria that form eyes through metabolism of

citrate in the cheese. The flavor and physical proper-

ties of the types with eyes usually differ, but variants

of these types can be quite similar, as exemplified by

the recently developed Maasdam cheese and highly

aged Gouda cheese. The classification in Figure 1 also

segregates varieties that evolved from the early prac-

tices of preservation by using high levels of sodium

tbl0001 Table 1 Classification of cheeses based on firmness and

maturation processes

Very hard (grating)

Ripened by bacteria (e.g., Parmesan)

Hard

Ripened by bacteria that form eyes in cheese (e.g., Swiss)

Ripened by bacteria without eye formation (e.g., Cheddar)

Semisoft

Ripened principally by bacteria (e.g., Gouda)

Ripened by bacteria and surface microorganisms

(e.g., Limburger)

Ripened principally by blue mold in the interior of the cheese

(e.g., Roquefort)

Soft

Ripened (e.g., Brie)

Unripened (e.g., cottage)

Fox PF, Guinee TP, Cogan TM and McSweeney PL (2000) Fundamentals of

Cheese Science, pp. 1–18, 388–428. Gaithersburg, MD: Aspen.

CHEESES/Types of Cheese 1047

chloride or high heat treatments of the curd (pasta-

filata varieties). The need for preservation has

lessened so that modern versions of the high salt

cheeses may contain salt concentrations sufficient to

satisfy tastes of consumers. The pasta-filata types,

especially Mozzarella cheese, have become global

favorites as ingredients in a variety of foods, espe-

cially pizza. It is unlikely that the originators of Moz-

zarella cheese envisioned that heat preservation

would yield a product that possessed the functional

stability and melt properties that fit the require-

ments as an ingredient in pizza. Acute perception of

tbl0002 Table 2 Classification of cheeses according to composition,

firmness, and maturation agents

Soft Cheese (50^80% moisture)

Unripened ^ low-fat

Cottage

Quark

Baker’s

Unripened ^ high-fat

Cream

Neufcha

tel

Unripened stretched curd or pasta filata cheese

Mozzarella

Scamorze

Ripened by external mold growth

Camembert

Brie

Ripened by bacterial fermentation

Kochkse

Handkse

Caciotta (ewe or goat)

Salt-cured or pickled

Feta – Greek

Domiati – Egyptian

Surface-ripened

Liederkranz

Semisoft Cheese (39^50% moisture)

Ripened by internal mold growth

Blue

Gorgonzola

Roquefort (sheep’s milk)

Surface-ripened by bacteria and yeast (surface smear)

Limburger

Brick

Trappist

Port du Salut, St. Paulin

Oka

Ripened primarily by internal bacterial fermentation but may also

have some surface growth

Mnster

Bel Paese

Tilsiter

Ripened by internal bacterial fermentation

Pasta Filata

Provolone

Low-moisture Mozzarella

Internally ripened by bacterial fermentation plus CO

production

resulting in holes or ‘eyes’

Gouda

Edam

Samsoe

Hard Cheese (maximum 39 ^ 40% moisture)

Internally ripened by bacterial fermentation

Cheddar

Colby

Caciocavallo

Internally ripened by bacterial fermentation plus CO

production

resulting in holes or ‘eyes’

Swiss (Emmental)

Gruyere

Internally ripened by mold growth

Stilton

Very hard cheese (maximum 34% moisture)

Asiago Old

Parmesan, Parmigiano, Grana

Romano

Sardo

Whey cheese

Heat and acid denaturation of whey protein

Ricotta (60% moisture)

Condensing of whey by heat and water evaporation

Gjetost (goat milk whey, 13% moisture)

Myost, Primost (13–18% moisture)

Spiced cheese

Caraway – caraway seeds

Noekkelost – cumin, cloves

Kuminost – cumin, caraway seeds

Pepper – peppers

Sapsago – hard grating, clover

From Olson NF (1995) Cheese. In: Rehm H-J and Reed G (eds)

Biotechnology, 2nd edn., vol. 9, pp. 355–384. VCH: Weinheim.

tbl0003Table 3 Classification of cheeses by manufacturing and

maturation processes

Natural cheeses

Cheese varieties in which milk is clotted by acid:

Cottage cheese

Baker’s cheese

Cream cheese

Neufcha

tel cheese

Cheese varieties in which milk is clotted by proteases:

Cheddar cheese

Colby and stirred curd (granular) cheese

Surface-ripened cheeses – Brick cheese, Limburger

cheese, Port du Salut, Bel Paese, Tilsit cheeses

Other semisoft cheeses – Edam, Gouda, Monterey,

Mnster cheeses

Cheeses with eyes – Swiss, Gruye

re, Samsoe

Italian type

Very hard (grating) – Parmesan, Romano

Other hard – Asiago, Fontina

Pasta Filata – Provolone, Mozzarella

Mold-ripened

Blue, Roquefort

Cheese with surface mold – Camembert, Brie,

Coulommiers

Process cheese

Processed Swiss, processed Cheddar, etc.

Cold-pack cheese

From Olson NF (1995) Cheese. In: Rehm H-J and Reed G (eds)

Biotechnology, 2nd edn., vol. 9, pp. 355–384. VCH: Weinheim.

1048 CHEESES/Types of Cheese

accidents in food preparation and subsequent science

and technology created this unexpected and wide-

spread usage.

Homogeneity and Diversity

0012 In spite of the great number of cheese types, there

are common elements in the manufacture of all var-

ieties of cheese. These are clotting of milk to yield a

curd, expulsion of serum/whey from the curd,

forming the grains of curd into a final shape, and

storage either for very limited periods for unaged

cheeses or for varying lengths of time to attain the

desired flavor and physical characteristics (See

Cheeses: Chemistry and Microbiology of Matur-

ation). The organization of these elements and the

flow of the cheesemaking process are illustrated in

Figure 2. The bases for diversity in cheeses are also

evident in Figure 2 starting with the type, compos-

ition, chemistry, and biology of the milk. Agents and

conditions at each of the steps in cheese manufactur-

ing impart specific effects that create further diversity

to create a cheese type with unique flavor, texture,

and functional properties. Additional discussion

of the microbiology, chemistry, and technologies of

important cheese types are given in the succeeding

articles.

See also: Cheeses: Starter Cultures Employed in Cheese-

making; Chemistry of Gel Formation; Chemistry and

Microbiology of Maturation; Manufacture of Extra-hard

Cheeses; Manufacture of Hard and Semi-hard Varieties of

Cheese; Cheeses with ‘Eyes’; Soft and Special Varieties;

White Brined Varieties; Quarg and Fromage Frais;

Processed Cheese; Surface Mold-ripened Cheese

Varieties; Surface Mold-ripened Cheese Varieties

Emmental

Grayere

Maasdam

Acid coagulated

Cottage

Cream

Quarg

Queso Blanco

Cheese

Heat/acid coagulation

Ricotta

Concentration/crystallization

Mysost

Rennet-coagulated

Internal bacterially ripened

Mold-ripened

Surface-ripened

Brick

Havarti

Limburger

Munster

Port du Salut

Trappist

Taleggio

Tilsit

Internal mold

(usually P. roqueforti

)

Roqueforti

Danablu

Gorgonzola

Stilton

Surface mold

(usually P. camemberti)

Brie

Camemberti

Carre del Est

Extra-hard

Grana Padano

Parmesan

Asiago

Sbrinz

Hard

Semi-hard

Cheese with eyes

High salt varieties

Pasta-filata varieties

Mozzarella

Kashkaval

Provolone

Domiati

Feta

Eyes caused by

citrate metabolism

Dutch-type

Edam

Gouda

Swiss-type

(Lactate metabolism

by Propionibacterium ssp.)

Caerphilly

Mahon

Monterey Jack

Cheddar

Cheshire

Graviera

Ras

fig0001 Figure 1 Classification of cheese into superfamilies based on the method of coagulation of milk or milk components with further

subdivision based on the principal ripening agents and/or characteristic technology. From Fox PF, Guinee TP, Cogan TM and

McSweeney PL (2000) Fundamentals of Cheese Science, pp. 1–18, 388–428. Gaithersburg, MD: Aspen, with permission.

CHEESES/Types of Cheese 1049

Composition

Species

Breed

Stage of lactation

Plane of nutrition

Animal health

Composition

− Casein

− Fat

− Calcium

− pH

− Enzymes

Public health and safety

Natural creaming

Centrifuge

Milk powder

Acid production

Phase sensitivity

Ripening properties

Rate of lysis

Selection criteria

Raw milk

Thermization

Standardization

Pasteurization

Color

CaCl

GDL

Starter culture

Secondary/adjunct culture

Rennet

Type

Amount

− Cheese yield

− Curd composition

− Curd syneresis

− Curd composition

− Acidification

− Retention of coagulant

Cut

Coagulum

Curds/whey

− Cook

− Agitate

− Drain

Curd syneresis

Curd composition

Whey

Curds

− Acidification

− Dehydration

− Texturization?

− Salting?

− Molding

− Pressing?

Unripened/fresh cheese

− Salting

− Special secondary cultures

− Coating/packaging

− Composition

− Temperature

− Humidity

− Time

Ripening

Flavor

Moisture

NaCl

Fat

Mature cheese

Functional properties

Texture

− Proteolysis

− Lypolysis

− Glycolysis

− Secondary changes

Rennet

Milk enzymes

Starter enzymes

Secondary culture

Adventitious microflora

− Syneresis

− Curd composition

− Curd structure

− Retention of coagulant

− Solubilization of CCP

Gel strength

Subjective/objective assessment

− Cheese yield

− Curd composition

Cheese milk

On-farm

Transport

In factory

Hygiene

Temperature

Time

Somatic cell count

Microbiological quality

Acidification -

Cheese quality

fig0002 Figure 2 Flow diagram of cheese manufacturing to show the common elements for all types and the ingredients, factors, and

technologies that create the diversity of cheese types. From Fox PF, Guinee TP, Cogan TM and McSweeney PL (2000) Fundamentals of

Cheese Science, pp. 1–18, 388–428. Gaithersburg, MD: Aspen, with permission.

1050 CHEESES/Types of Cheese

Further Reading

Codex Committee on Milk and Milk Products (2000) Pro-

posed Draft Amendment to the Codex Standard for

Cheese. 4th Session of the Codex Committee on Milk

and Milk Products, Appendix IV. Wellington, New

Zealand, February 28 to March 3, 2000.

Fox PF (1999) Cheese: an overview. In: Cheese: Chemistry,

Physics and Microbiology, pp. 1–35. Gaithersburg, MD:

Aspen.

Fox PF, Guinee TP, Cogan TM, and McSweeney PL (2000)

Fundamentals of Cheese Science, pp. 1–18, 388–428.

Gaithersburg, MD: Aspen.

Olson NF (1995) Cheese. In: Rehm H-J and Reed G (eds.)

Biotechnology, 2nd edn. vol. 9, pp. 355–384. Weinheim:

VCH.

Starter Cultures Employed in

Cheese-making

G Stanley, Rhodia Food UK Ltd, Woodley, Stockport,

Background

0001 The bacteria used in cheesemaking are commonly

referred to as ‘lactic acid bacteria’ (LAB), having

lactic acid as their main end product of lactose and

other sugar fermentations. It is this acid that plays

a major role in the preservation of cheese. Cheese-

making LAB have a ‘Generally Regarded As Safe’

(GRAS) status and are roughly divided into meso-

philic and thermophilic types. Commercial cheese

cultures are used for the production of the majority

of the developed world’s cheeses and for the most part

are balanced blends of selected single strain cultures.

Such preparations are offered in either a direct vat

inoculation (DVI) or a bulk starter (BS) format.

Development of Starter Cultures

0002 LAB occur naturally in raw milk, and initially, cheese-

making relied on these indigenous bacteria to

promote acid production; however, this must have

resulted in very variable fermentations. Cheese-

makers soon developed the technique of inoculating

fresh milk with whey from the previous day’s cheese-

making – a crude form of starter inoculation, but a

technique that is still used in some cheesemaking

operations today. The first commercial cultures were

prepared as powdered starters by Chr. Hansen

Laboratories (Denmark) just before the end of the

nineteenth century. These were likely to have been

mixtures of strains of unknown composition, com-

mercial undefined starters, and for the first half of the

twentieth century, such commercial mixtures sup-

plied to creameries in liquid, frozen, or dried form

were the dominant starter types. The discovery of the

bacterial nature of starters owes much to the work of

Pasteur (mid 1800s), Lister, who isolated Bacterium

lactis (now called Lactococcus lactis) in 1873, and

Orla-Jensen, who published his thesis on the nature of

starter cultures in 1919. Whitehead (New Zealand),

in the 1930/40s, pioneered the concept of single

strains, while identifying bacteriophage (phage) as

an important causative agent in slow cheese fer-

mentations. This use of (blended) single strains, well

characterized for phage resistance, acid production,

and flavor delivery has now been widely adopted.

0003Concentrated starter cultures, developed in the

1960s and 1970s, were prepared in freeze-dried or

deep-frozen form, which required simple inoculation

into a bulk starter vessel (containing, traditionally,

milk, or reconstituted milk powder or a phage-

inhibitory whey-based phosphated medium). Im-

provements to this concentration process have led,

in the last 10–20 years, to the development and com-

mercial acceptance of DVI cultures that require no

subculture or activation prior to use. In the UK in

2000, more than 50% of all cheese was made using

DVI systems.

Microbiology of Starter Cultures

0004LAB can be divided broadly into mesophiles and

thermophiles, which have an optimum growth tem-

perature of approximately 32 or 45



C, respectively.

Mesophilic Starters

0005Lactococcus lactis (Lc. lactis) is the dominant acidify-

ing mesophile species used, with Leuconostoc mesen-

teroides ssp. cremoris, a weakly acidifying culture,

being used to impart flavor in certain (fresh) dairy

fermentation. Lc. lactis has two subspecies, namely

cremoris and lactis, and also a biovariant diacetylac-

tis, now referred to as Lc. lactis citrateþ, which is

able to catabolize citrate (found in milk at approxi-

mately 0.2%) to carbon dioxide and the flavor com-

pound, diacetyl – both of these are technologically

important products. Traditionally, strains of Lc. lactis

cremoris have been regarded as producing the best

flavors in cheese, whereas some strains of Lc. Lactis

ssp. lactis are noted for promoting certain off-flavors

(bitter, malty, fruity). However, better selection tech-

niques have identified many Lc. Lactis ssp. lactis

strains suitable for delivering good flavors and,

CHEESES/Starter Cultures Employed in Cheese-making 1051

because of their faster rates of lactic acid production

and better yields in concentrated culture preparation,

are now regularly used in commercial starters, usually

blended with Lc. lactis ssp. cremoris strains.

Thermophilic Starters

0006 The most important thermophilic LAB are Strepto-

coccus salivarius ssp. thermophilus (Sc. thermophi-

lus) and species of Lactobacillus (Lb): bulgaricus,

helveticus and lactis. They are used in those technolo-

gies where a temperature > 40



C is used, such as

yogurt, Mozzarella, Emmenthal, and Gruyere. Gen-

erally, these fermentations use blends of strains of Sc.

thermophilus and a Lactobacillus (particulary Lb.

bulgaricus), there being an associative growth rela-

tionship between them: Sc. thermophilus produces

formate that stimulates Lb. bulgaricus, and Lb. bul-

garicus produces amino acids that stimulate Sc. ther-

mophilus.

0007 Some differentiating characteristics of mesophilic

and thermophilic acidifying starter cultures are given

in Table 1.

Function of Starter Cultures

0008 Three main technological functions can be attributed

to LAB starter cultures, namely acidification, texture

enhancement, and flavor development. Acidification,

the metabolism of lactose to lactic acid, is the major

attribute of LAB; the method of this metabolism

differs in the various species.

0009 Lactococci actively transport the lactose across the

cell wall membrane as lactose-phosphate, which is

hydrolyzed to glucose and galactose-6-phosphate;

the glucose molecule is then metabolised to l(þ) lac-

tate by the glycolytic pathway, and the galactose is

metabolized via the tagatose-6-phosphate pathway.

The thermophilic LAB also use the glycolytic path-

way, but they differ from lactococci in several

respects, namely the lactose uptake mechanism, and

that St. thermophilus and Lb. bulgaricus are not able

to metabolize galactose, whereas Lb. helveticus me-

tabolizes it via the Leloir pathway. The isomeric form

of lactate produced also varies between the different

species (see Table 1). It should be noted that for

starters, the fermentation of lactose is their energy-

producing mechanism, and lactate is merely a waste

product. The LAB starters are referred to as ‘homo-

fermentative cultures,’ i.e. they produce one main end

product (lactate); in contrast, Leuconostocs can fer-

ment lactose to lactate, ethanol, and carbon dioxide

via the phosphoketolase pathway, and are regarded as

heterofermentative bacteria.

0010 The process of acidification enhances the expulsion

of whey from the curd during the cheesemaking

process and promotes the development of the texture

of the cheese. The final pH obtained in the cheese will

dictate to a large extent the texture of the curd: in very

acid curds, e.g., Stilton, Cheshire (pH 4.6–4.8), the

texture is described as short, noncohesive and crum-

bly due to the low level of calcium and the small size

of the casein aggregates, whereas high pH cheeses

(e.g., Edam/Gouda, pH 5.3–5.5) have a springy or

plastic texture with a high level of calcium and larger

casein aggregates.

0011Some LAB are able to polymerize galactose and

glucose to give polysaccharide molecules, these can

be important in modifying the texture of fermented

dairy products – they are particularly useful in yogurts,

and in low and reduced fat products, as they can

improve texture and act as a fat replacer. Strains of

Sc. thermophilus have been particularly useful in this

respect. Eye formation is important in certain cheese

(e.g., Dutch varieties), and occurs as a result of

carbon dioxide produced by the fermentation of

citrate by citrateþ Lc. lactis ssp. diacetylactis and

Leuconostoc strains in the starter.

0012LAB are important in flavor development due to

both the end products of fermentation (particularly

diacetyl from citrate fermentation) and the slow pro-

teolysis of the milk proteins to peptides and amino

acids by the protinases and peptidases of the LAB that

are released into the curd matrix as the cells die and

autolyze during the cheese maturation.

0013A fourth function often attributed to LAB is that of

the health benefits, which are further discussed under

the probiotic section of secondary cheese cultures.

Selection, Production, and Use of LAB

0014With the increasing use of LAB cultures in a concen-

trated form, emphasis has been placed on the selec-

tion process for isolating strains, the functions of

which match the cheesemaking requirements. Raw

milk, traditional mixed starters, and dairy products,

in general, are a valuable source of natural LAB;

selection tests that are conducted on strain isolates

from these sources include:

0015flavor promotion, absence of off-flavors;

0016acidification rates at different temperatures;

0017phage insensitivity;

0018compatability with other strains (absence of

bacteriocin/inhibitor production);

0019temperature sensitivity;

0020salt sensitivity;

0021proteolytic activity;

0022special attributes, e.g., polysaccharide produc-

tion;

0023cell yield in industrial fermentation;

1052 CHEESES/Starter Cultures Employed in Cheese-making

tbl0001 Table 1 Some differentiating characteristics of starter lactic acid bacteria

Type Species Shape Growth at Lactate

isomer

Citrate

metabolism

Galactose

metabolism

Ammonia

from arginine

Percentage lactic acid

produced in milk

Percentage

salt inhibition

Important

metabolicproducts



C40

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C45

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Mesophilic Lactococcus lactis ssp. lactis Cocci þþ

L (þ) þþ 0.8 4.0–6.5 Lactate

Lactococcus lactis ssp. lactis (citþ) Cocci þþ

L (þ) þþþ 0.8 4.0–6.5 Lactate, diacetyl, CO

Lactococcus lactis ssp. cremoris Cocci þL (þ) þ 0.8 2.0–4.0 Lactate

Leuconostoc mesenteroides

ssp. cremoris

Cocci þ

D () þþ 0.2 2.0–4.0 Lactate, diacetyl, CO

Thermophilic Streptococcus thermophilus Cocci þþL (þ)  1.2 <2.0 Lactate, acetaldehyde

Lactobacillus bulgaricus Rods þþ

D ()  1.8 <2.0 Lactate, acetaldehyde

Lactobacillus helveticus Rods þþ

DL þ 2.0 <2.0 Lactate

Lactococcus lactis Rods þþ

D () þ/ 1.8 2.0–4.0 Lactate

10.0024 stability during cell concentration;

11.

0025 stability in freeze-dried or frozen format;

12.

0026 acid-producing activity as in DVI cultures.

Genetic techniques developed for bacteria have

allowed the further modification of selected cultures

to improve their functionality for cheesemaking

purposes. Initial studies in this area concentrated on

improving the phage resistance of cultures, with the

knowledge that certain plasmids in LAB coded for

functions relating to the phage infection process.

Other areas that have been targeted for such develop-

ment include food safety (ability of LAB to inhibit

pathogen growth), and flavor (transfer of the genes of

protein/peptide degrading enzymes, transfer of the

citrate fermentation genes coded on plasmids). Al-

though much research has been conducted on the

genetics of LAB, its transference into commercial

applications has received a setback, particularly in

Europe, with the strength of the antigenetic modifica-

tion lobby.

0027 Once a strain has been selected as a suitable com-

mercial culture, it will be stored as seed cultures in a

culture bank (freeze-dried or deep-frozen) in multiple

copies in an easy to use form ready for future com-

mercial productions. The seed cultures are activated

and grown in a small volume of a selected sterile

nutritive medium, then inoculated into an industrial

fermenter and grown under strict time, temperature,

and pH conditions. The use of pH control (usually at

pH 6.2–6.5 for mesophilic and pH 6.0–5.5 for

thermophilic LAB) to neutralize the lactic acid pro-

duced allows the culture to attain a level of 10e10

bacteria per milliliter. Following concentration by

either centrifugation or membrane techniques, the

final cell numbers achieved are between 10e11 and

10e12. The cultures are then standardized for their

acid-producing activity or cell numbers and frozen (in

pellet form for DVI cultures) or freeze-dried; often,

cryoprotective agents (e.g., sugars such as sucrose and

lactose) are added at this stage to enhance culture

stability. Finally, the cultures are blended in predeter-

mined ratios and packaged in sachets or cartons and

enter commercial stock once they have passed the

appropriate bacteriological/activity quality control

tests. Culture blends usually contain between two

and six strains and are prepared on the basis of activ-

ity, flavor promotion, and phage relationships of the

individual components. Mesophilic LAB are used for

the majority of cheese fermentations (Dutch, Ched-

dar, French mold-ripened, cottage, soft cheeses), with

thermophilic cultures being used mainly for Italian

(Parmasan, Mozzarella, and Pizza) cheeses, Swiss

cheese varieties, and yogurt. However, there is an in-

creasing trend to blend mesophilic and thermophilic

LAB for certain technologies such as Cheddar and

Brie cheeses. The inclusion of Sc. thermophilus in

mesophilic cultures, together with an increase in the

vat milk temperature, produces a ‘stabilized’ Brie that

has a more uniform texture and longer shelf-life than

traditional products. In Cheddar DVI cultures, the

inclusion of Sc. thermophilus enhances culture activ-

ity, reduces bitter notes, and increases phage durabil-

ity; DVI cultures containing Sc. thermophilus now

account for at least 30% of UK Cheddar. Lb. helveti-

cus strains are also being used commercially for

Cheddar to enhance and modify flavor profiles, and

these strains are being offered either as adjunct

cultures or preblended with the DVI culture.

0028The preparation of bulk starter in the cheese plant

involves inoculating the bulk starter culture (usually

freeze-dried, in a sachet, or deep-frozen, in a ring-pull

can – in the latter case, partial thawing of the culture

is required prior to inoculation) into the precleaned

and sterilized bulk starter vessel. The growth medium

normally used is either skim milk/reconstituted skim

milk powder (10–12%) or a blended powder (6%),

containing a protein source (whey/milk powder), a

sugar source (whey powder/lactose), a bacterial

growth stimulant (yeast extract), and a buffering/

phage inhibitory agent (phosphate salts). The inocu-

lated culture is grown for a predetermined time at a

constant temperature (e.g., 18 h at 22–24



C for

mesophilic cultures, and 5–6h at 40–42



C for

thermophilic cultures). During incubation, the pH

evolution may be monitored, and also pH control

may be used, whereby alkali (ammonia) is automatic-

ally dosed into the vessel to maintain the pH at the

optimum level for the culture (approximately pH

6.2–6.5 for mesophilic cultures and pH 6.0–5.5 for

thermophilic cultures). Once the required end point

has been reached (as determined by the pH/acidity

level, or quantity/rate of alkali addition), the bulk

starter is ready for use, ideally after rapid cooling.

Secondary Cheese Cultures

0029In addition to the mesophilic and thermophilic

starters described above, other microbial cultures

are used in cheese to produce the flavors, textures,

and appearance typical for that cheese type.

Molds

0030For Coulommier and Camembert type cheese, the

white mold, Penicillium camemberti, is used to give

a white felt on the surface of the cheese. Strains have

been isolated that exhibit different mycelial growth

characteristics, and in general, four types have been

identified:

1054 CHEESES/Starter Cultures Employed in Cheese-making

1.0031 Neufcha

tel form (rapid growth that produces a

thick mat of yellow–white mycelia);

0032 short, flat mycelial form (rapid growth and tight

flat thallus);

0033 long, tall mycelial form (slow growth, loose high

thallus);

0034 fluffy woolly mycelial form (white thallus that

turns gray on aging, originally called Penicillium

album);

The mold is added to the cheese as a spore suspension

either in the vat or sprayed on at the end of cheese-

making (or both).

0035 Geotrichum candidum is another surface mold,

which produces a very short, fine mycelium. It is

generally used together with P. camemberti and exerts

a synergistic effect on its growth. Some strains of

G. candidum produce a yeast-like appearance on

the surface of the cheese, often referred to as ‘toad-

skin.’

0036 Penicillium roqueforti is the mold culture used for

blue-veined cheeses, such as Roquefort, Stilton, Gor-

gonzola, and Danish Blue. Unlike P. camemberti,it

generally grows inside the cheese, but like P. camem-

berti, it requires oxygen to grow; therefore, after

cheesemaking, the cheese must be pierced to allow

sufficient oxygen to penetrate for spore germination

and for the carbon dioxide to be expelled.

Yeasts

0037 These form an important part of the microflora of

many surface ripened cheeses, such as blue cheeses,

soft mold-ripened cheeses, and washed-rind cheeses,

e.g., St. Nectaire, St. Paulin, Cantal. Kluyveromyces

lactis, Saccharomyces cerevisiae, Candida utilis,

Debaryomyces hansenii, and Rodosporidium infir-

mominiatum are the most common yeasts used.

They colonize the surface of the cheese at an early

age, are able to grow in 4% NaCl, and have a strong

neutralizing activity by virtue of their ability to me-

tabolize lactate. They are both proteolytic and lipo-

lytic and produce a range of volatile and peptide/

amino acid flavor components.

Bacteria

0038 Groups of bacteria that are important in the second-

ary flora of cheese are Micrococcus, Lactobacillus,

Corynebacterium, and Propionibacterium.

0039 Brevibacterium linens (Corynebacteria) is respon-

sible for the red–orange color and characteristic

aroma (originating from the catabolism of sulfur-

containing amino acids) of surface-smear and

washed-rind cheeses, such as Munster, Maroilles,

Pont L’Eveque and St. Paulin.

0040Micrococci cultures are facultative anaerobes and

are used to promote texture and flavor in both hard,

semihard and mold-ripened cheeses.

0041Mesophilic Lactobacillus species are used in

washed-rind cheeses and in some hard and semi-

hard cheeses; they are of value because of their

aminopeptidase activity, which promotes flavor and

can reduce bitterness during cheese maturation.

0042The microbiology of the surface smear and washed

rind cheeses is complex; combinations of Corynebac-

teria, Micrococci, molds, and yeasts are present. The

Corynebacteria grow once the pH has increased

due to the degradation of lactate by the yeasts and

molds.

0043Propionibacteria, principally the species Proprioni-

bacterium freudenreichii and Shermanii, are used

in Swiss cheese technology (Emmenthal, Gruyere,

Appenzell). They convert the lactate produced by

the Sc. thermophilus and Lb. helveticus starters to

the flavor components, propionic and acetic acids,

and carbon dioxide, which is responsible for eye

formation.

0044Probiotic bacteria form an addition group that are

used for their potential health-giving properties. The

main cultures used are certain Lactobacillus species

(particularly Lb. acidophilus) and Bifidobacterium

species, and are generally considered to be natural

inhabitants of the gut. They are usually added with

starter LAB, particularly the thermophilic LAB, since

they do not themselves normally produce sufficient

lactic acid for standard fermentations. They are used

mainly in the production of fresh fermented dairy

products (e.g., yogurts). Health benefits associated

with them include improved digestion, stimulation

of the immune system, reduction of tumor incidence,

and reduction of serum cholesterol. However, it has

proved difficult to obtain medical evidence in this

respect that is acceptable to health authorities.

Factors that Affect Culture Growth

0045The growth of LAB in milk can be affected by many

parameters. For example, variations in milk compos-

ition, either seasonal or cattle feed-influenced, can

have a stimulatory or inhibitory effect on LAB. Ex-

cessive entrainment of oxygen in the milk, as a result

of agitation, can cause inhibition due to the bacterial

conversion of oxygen into the inhibitory substance

hydrogen peroxide. LAB generally do not have the

enzyme catalase to degrade this. Milk may contain

antibiotic residues following the administration of

antibiotics for cow mastitis; however, strict quality-

control measures have significantly reduced this prob-

lem of recent times. Residues of cleaning and sterilizing

chemicals may be present in the cheesemaking vats

CHEESES/Starter Cultures Employed in Cheese-making 1055