Chapter 2

Overview of Cheese Manufacture

Summary The objective of this chapter is to present a very brief description of the
principal operations of cheese production so that the operations described in the
following chapters can be seen in an overall context

Introduction

The production of all varieties of cheese involves a generally similar protocol

(Fig. 2.1), various steps of which are modified to give a product with the desired
characteristics. The principal general steps are
1. Selection, standardization and, in most cases, pasteurization of the milk.
2. Acidification, usually via the in situ production of lactic acid by selected
bacteria.
3. Coagulation of the milk by acidification or limited proteolysis.
4. Dehydration of the coagulum to yield cheese curd, by a range of techniques,
some of which are variety-specific.
5. Forming the curds into characteristic shapes.
6. For most varieties, ripening (maturation) of the curd during which the character-
istic flavour and texture of the cheese develop.
The objective of this chapter is to present a very brief description of the principal
operations so that the operations described in the following chapters can be seen in
an overall context.

Keywords Selection and treatment of cheesemilk • Annato • Coagulation • Salting

• Ripening • Processed cheese

© Springer New York 2017 11

P.F. Fox et al., Fundamentals of Cheese Science,
DOI 10.1007/978-1-4899-7681-9_2
12 2 Overview of Cheese Manufacture

Fig. 2.1 General protocol for cheese manufacture

2.2 Standardization of Milk Composition 13

2.1 Selection of Milk

The composition of cheese is strongly influenced by the composition of the cheese

milk, especially the content of fat, protein, calcium and pH. The constituents of
milk, which are described in Chap. 4, are influenced by several factors, including
species, breed, individuality, nutritional status, health and stage of lactation of the
producing animal. Owing to major compositional abnormalities, milk from cows in
the very early or late stages of lactation and those suffering from mastitis should be
excluded. Somatic cell (leucocyte) count is a useful index of quality. Some genetic
polymorphs of the milk proteins have a significant effect on cheese yield and quality
and there is increasing interest in breeding for certain polymorphs. The milk should
be free of chemical taints and free fatty acids, which cause off-flavours in the cheese,
and antibiotics which inhibit bacterial cultures.
The milk should be of good microbiological quality, as contaminating bacteria
will be concentrated in the cheese curd and may cause defects or public health prob-
lems. This subject will be discussed in Chap. 5.

2.2 Standardization of Milk Composition

Milk for cheese is subjected to a number of pre-treatments, with various

objectives.
Different cheese varieties have a characteristic fat-in-dry matter content, in
effect, a certain fat-to-protein ratio and this situation has legal status in the “Standards
of Identity” for many cheese varieties. While the moisture content of cheese, and
hence the level of fat plus protein, is determined mainly by the manufacturing pro-
tocol, the fat:protein ratio is determined mainly by the fat:casein ratio in the cheese
milk. Depending on the ratio required, it can be modified by:
• removing some fat by natural creaming, as in the manufacture of Parmigiano
Reggiano, or centrifugation
• adding skim milk
• adding cream
• adding micellar casein (prepared by ultrafiltration)
• adding milk powder, evaporated milk or ultrafiltration retentate. Such additions
also increase the total solids content of the milk and hence cheese yield and will
be discussed in Chap. 10.
Calcium plays a major role in the coagulation of milk by rennet and subsequent
processing of the coagulum and hence it is common practice to add CaCl2 (e.g.,
0.01 %) to cheese milk.
The pH of milk is a critical factor in cheesemaking. The pH is inadvertently
adjusted by the addition of 1.5–2 % starter culture which reduces the pH of the milk
immediately by about 0.1 unit. Starter concentrates (sometimes called direct-to-vat
starters), which are now used widely, have no immediate acidifying effect.
14 2 Overview of Cheese Manufacture

Previously, it was standard practice to add the starter to the cheese milk 30–60 min
before rennet addition. During this period, the starter microorganisms began to
grow and produce acid, a process referred to as “ripening”. Ripening served a num-
ber of functions:
• it allowed the starter bacteria to enter their exponential growth phase and hence
to be highly active during cheesemaking; this is not necessary with modern high-
quality starters.
• the lower pH was more favourable for rennet action and gel formation.
However, the practice increases the risk of bacteriophage infection of the starter
as phage become distributed throughout the liquid milk but is reduced after the milk
has coagulated (see Chap. 6). Although ripening is still practiced for some varieties,
it has been discontinued for most varieties.
The pH of milk on reception at the dairy is higher today than it was previously
owing to improved hygiene during milking and the more widespread use of refrig-
eration at the farm and factory. In the absence of acid production by contaminating
bacteria, the pH of milk increases slightly during storage due to the loss of CO2 to
the atmosphere. The natural pH of milk is ~6.6–6.7 but varies somewhat (e.g., it
increases in late lactation and during mastitic infection).
To offset these variations and to reduce the pH as an alternative to ripening, the
pre-acidification of milk by 0.1–0.2 pH units is recommended, either through the
use of the acidogen, gluconic acid-δ-lactone, or by limited growth of a lactic acid
starter, followed by pasteurization (referred to as pre-maturation).

O
O
C OH
C
HC OH
HC OH
HO C H
HO C H H2O
O
HC OH
HC OH
HC OH
HC
CH2OH
CH2OH

Gluconic acid-d-lactone Gluconic acid

2.3 Heat Treatment of Milk

Traditionally, all cheese was made from raw milk, a practice which remained
widespread until the 1940s. Even today, significant amounts of cheese are made in
Europe from raw milk. The use of raw milk may be undesirable due to:
• Public health safety
• The presence of undesirable microorganisms which may cause defects or vari-
ability in flavour and/or texture.
2.4 Cheese Colour 15

When cheese was produced from fresh milk on farms or in small, local facto-
ries, the growth of contaminating microorganisms was very low but as cheese
factories became larger, storage of milk for longer periods became necessary and
hence the microbiological quality of the milk varied. For public health reasons, it
became increasingly popular from the beginning of the twentieth century to
pasteurize milk for liquid consumption. The pasteurization of cheese milk became
widespread about 1940, primarily for public health reasons, but also to provide
a milk supply of more uniform bacteriological quality and to improve its keeping
quality. Although a considerable amount of cheese is still produced from raw
milk, on both an artisanal and factory scale, especially in southern Europe
(including such famous varieties as Swiss Emmental, Gruyère de Comté,
Parmigiano Reggiano and Grano Padano), pasteurized milk is now generally
used, especially in large factories. The flavour of cheese made from raw milk is
different from and more intense than that from pasteurized because beneficial
indigenous LAB, which may contribute positively to cheese flavour, are killed by
pasteurization, To counteract the loss of such LAB, it is becoming increasingly
common to add a culture of selected LAB (lactobacilli) to cheese milk in addition
to the main acid-producing culture. Some indigenous enzymes, e.g., lipase, which
may contribute positively to cheese ripening, are also inactivated by pasteuriza-
tion. A sub-pasteurization temperature, eg., 68–70 °C may be used for cheese
milk and a temperature >72 °C × 15 s should not be used, owing to damage to the
cheesemaking properties of milk (see Chaps. 7 and 8). Aspects of pasteurization
are discussed in Chap. 5.
There are four alternatives to pasteurization for reducing the number of microor-
ganisms in milk:
• treatment with H2O2
• Activation of the lactoperoxidase-H2O2-thiocyanate system.
• Bactofugation
• Microfiltration
These processes are also discussed briefly in Chap. 5.

2.4 Cheese Colour

Colour is a very important attribute of foods and serves as an index of quality,

although in some cases, this is cosmetic. The principal indigenous pigments in
milk are carotenoids which are obtained from the animal’s diet, especially from
fresh grass and clover. The carotenoids are secondary pigments involved in
photosynthesis; the structure of β-carotene is shown in Fig. 2.2. Owing to the con-
jugated double bond system, carotenoids absorb ultraviolet and visible light,
giving them colours ranging from yellow to red. They are responsible for the
16 2 Overview of Cheese Manufacture

Fig. 2.2 Structures of β-carotene and retinol

colour of many foods, e.g., carrots, squashes, peppers, maize; they are also present
in the leaves of plants in which their colour is masked by the green chlorophylls.
Some carotenoids have pro-vitamin A activity and may be converted to retinol
(vitamin A; Fig. 2.2) in the body.
Animals do not synthesize carotenoids but absorb them from plant materials
in their diet. In addition to serving as pro-vitamin A, some animals store carot-
enoids in their tissues, which then acquire a colour, e.g., salmon, cooked lobster
and egg yolk. Cattle transfer carotenoids to adipose tissue and milk but goats,
sheep and buffalo do not. Therefore, bovine milk and products made therefrom
are yellow to an extent dependent on the carotenoid content of the animal’s diet.
Products such as butter and cheese made from sheep, goat or buffalo milk are
very white in comparison with their counterparts made from bovine milk. This
yellowish colour may make products produced from cows’ milk less acceptable
than products produced from sheep’s, goats’ or buffalo milk in Mediterranean
countries where the latter are traditional. The carotenoids in bovine milk can be
bleached by treatment with H2O2 or benzoyl peroxide or masked by chlorophyll
or titanium oxide (TiO2), although such practices are not permitted in all
countries.
At the other end of the spectrum are individuals who prefer highly coloured
cheese, butter or egg yolk. Such intense colours may be obtained by adding carot-
enoids (synthetic or natural extracts) directly to the product or to the animal’s diet.
In the case of cheese and dairy products, annatto, extracted from the pericarp of the
seeds of the annatto plant (Bixa orellana), a native of Brazil, is used most widely.
Annatto contains two apocaroetnoid pigments, bixin and norbixin (Fig. 2.3). By
suitable modification, the annatto pigments can be made fat-soluble, for use in but-
ter or margarine, or water-soluble for use in cheese.
Initially, annatto may have been used in cheese manufacture to give the impres-
sion of a high fat content in partially skimmed cheese but some people believe that
coloured (“red”) cheese tastes better than its white counterpart of equivalent
quality.
2.5 Conversion of Milk to Cheese Curd 17

Fig. 2.3 Structures of cis-bixin and norbixin, the apocarotenoid pigments in annatto

2.5 Conversion of Milk to Cheese Curd

After the milk has been standardized, pasteurized or otherwise treated, it is trans-
ferred to vats (or kettles) which vary in shape (hemi-spherical, rectangular, vertical
or horizontal cylindrical), may be open or closed and may range in size from a few
hundred litres to 20,000–40,000 L [a selection of vats are shown in Fig 2.4]. Here,
it is converted to cheese curd, a process that involves three basic operations: acidifi-
cation, coagulation and dehydration.

2.5.1 Acidification

Acidification is usually achieved by the in situ production of lactic acid through the
fermentation of the milk sugar, lactose, by lactic acid bacteria. Initially, the indige-
nous milk microflora was relied upon to produce acid but since this microflora is
variable, the rate and extent of acidification are variable, resulting in cheese of vari-
able quality. Cultures of lactic acid bacteria for cheesemaking were introduced com-
mercially about 130 years ago and have been progressively improved and refined.
The science and technology of starters are described in Chap. 6. The acidification of
curd for some artisanal cheeses still relies on the indigenous microflora.
Direct acidification using acid (usually lactic or HCl) or acidogen (usually glu-
conic acid-δ-lactone) may be used as an alternative to biological acidification and is
used commercially to a significant extent in the manufacture of Cottage, Quarg,
Feta-type cheese from UF-concentrated milk and Mozzarella. Direct acidification is
18 2 Overview of Cheese Manufacture

6
2

Fig. 2.4 Examples of vats used for cheesemaking

more controllable than biological acidification and, unlike starters, is not suscepti-
ble to phage infection. However, in addition to acidification, the starter bacteria
serve very important functions in cheese ripening (see Chaps. 11 and 12) and hence
chemical acidification is used mainly for cheese varieties for which texture is more
important than flavour.
The rate of acidification is fairly characteristic of the variety and its duration
ranges from 5 to 6 h for Cheddar and Cottage to 10–12 h for Dutch and Swiss types.
The rate of acidification, which depends on the amount and type of starter used and
on the temperature profile of the curd, has a major effect on the texture of cheese,
mainly through its solubilizing effect on colloidal calcium phosphate; this subject is
discussed in Chap. 14.
2.5 Conversion of Milk to Cheese Curd 19

Regardless of the rate of acidification, the ultimate pH of the curd for most hard
cheese varieties is in the range 5.0–5.3 but it is 4.6 for the soft, acid-coagulated
varieties, e.g., Cottage, Quarg and Cream, and some rennet-coagulated varieties,
e.g., Camembert and Brie.
The production of acid at the appropriate rate and time is a key step in the manu-
facture of good quality cheese. Acid production affects several aspects of cheese
manufacture, many of which will be discussed in more detail later:
• Coagulant activity during coagulation (Chap. 7).
• Denaturation and retention of the coagulant in the curd during manufacture and
hence the level of residual coagulant in the curd; this influences the rate of pro-
teolysis during ripening, and may affect cheese quality (Chaps. 8 and 12).
• Curd strength, which influences cheese yield (Chap. 10).
• Gel syneresis, which controls cheese moisture and hence regulates the growth of
bacteria and the activity of enzymes in the cheese; consequently, it strongly influ-
ences the rate and pattern of ripening and the quality of the finished cheese
(Chaps. 8, 12 and 15).
• The rate of acidification determines the extent of dissolution of colloidal cal-
cium phosphate which modifies the susceptibility of the caseins to proteolysis
during ripening and influences the rheological properties of the cheese, e.g.,
compare the texture of Emmental, Gouda, Cheddar and Cheshire cheese (see
Chap. 14).
• Acidification controls the growth of many non-starter bacteria in cheese, includ-
ing pathogenic, food-poisoning and gas-producing microorganisms; properly-
made cheese is a very safe product from the public health viewpoint (see
Chap. 19).
The level and time of salting have a major influence on pH changes in cheese.
The concentration of NaCl in cheese (commonly 0.7–4 %, equivalent to 2–10 %
salt in the moisture phase) is sufficient to halt the growth of starter bacteria. Some
varieties, mostly of British origin, are salted by mixing dry salt with the curd
toward the end of manufacture and hence the pH of curd for these varieties must be
close to the ultimate value (~ pH 5.1) at salting. However, most varieties are salted
by immersion in brine or by surface application of dry salt; salt diffusion in cheese
moisture is a relatively slow process and thus there is ample time for the pH to
decrease to ~5.0 before the salt concentration becomes inhibitory throughout the
interior of the cheese. The pH of the curd for most cheese varieties, e.g., Swiss,
Dutch, Tilsit, Blue, etc., is 6.2–6.5 at moulding and pressing but decreases to
~5–5.2 during or shortly after pressing and before salting. The significance of vari-
ous aspects of the concentration and distribution of NaCl in cheese are discussed
in Chap. 9.
In a few special cases, e.g., Domiati, a high level of NaCl (10–12 %) is added to
the cheesemilk, traditionally to control the growth of the indigenous microflora.
This concentration of NaCl has a major influence, not only on acid development, but
also on rennet coagulation, gel strength and curd syneresis.
20 2 Overview of Cheese Manufacture

2.5.2 Coagulation

The essential characteristic step in the manufacture of all cheese varieties involves
coagulation of the casein component of the milk protein system to form a gel which
entraps the fat, if present. Coagulation may be achieved by:
• Limited proteolysis by selected proteinases (rennets);
• Acidification to ~pH 4.6;
• Acidification to a pH value >4.6 (perhaps ~5.2) in combination with heating to
~90 °C.
The majority of cheese varieties, and ~75 % of total production, are produced by
rennet coagulation but some acid-coagulated varieties, e.g., Quarg, Cottage and
Cream, are of major importance. The coagulation of milk by rennets or acid are
discussed in Chaps. 7 and 16, respectively. Acid-heat-coagulated cheeses are of
relatively minor importance and are usually produced from whey or a blend of whey
and skim milk and probably evolved as a useful means for recovering the
nutritionally-valuable whey proteins. Their properties are very different from those
of rennet- or acid-coagulated cheeses and they are usually used as food ingredients.
Important varieties are Ricotta and related varieties (indigenous to Italy), Anari
(Cyprus) and Manouri (Greece) (see Chaps. 3 and 18).
A fourth, minor, group of cheeses is produced, not by coagulation, but by ther-
mal evaporation of water from a mixture of whey and skim milk, whole milk or
cream and crystallization of lactose. Varietal names include Mysost and Gjetost.
These cheeses, which are almost exclusive to Norway, bear little resemblance to
rennet- or acid-coagulated cheeses and probably should be classified as whey prod-
ucts rather than cheese, sensu stricto.

2.5.3 Post-Coagulation Operations

Rennet or acid-coagulated milk gels are quite stable if maintained under quiescent
conditions but if cut or broken, they synerese, expelling whey. Syneresis essentially
concentrates the fat and casein of milk by a factor of 6–12, depending on the variety.
In the dairy industry, concentration is normally achieved through thermal evapora-
tion of water and more recently by removing water through semi-permeable mem-
branes. The syneresis of rennet- or acid-coagulated milk gels is thus a rather unique
method for dehydration, dependent on special characteristics of the caseins.
The rate and extent of syneresis are influenced, inter alia, by milk composition, espe-
cially the concentrations of Ca2+ and casein, pH of the whey, cooking temperature, rate
of stirring of the curd-whey mixture and, of course, time (see Chap. 8). The composition
of the finished cheese is determined by the extent of syneresis and since this is under the
control of the cheesemaker, it is here that the differentiation of the individual cheese
varieties really begins, although the type and composition of the milk, the amount and
type of starter and the amount and type of rennet are also significant in this regard.
2.5 Conversion of Milk to Cheese Curd 21

A more or less unique protocol has been developed for the manufacture of each
cheese variety. These protocols differ mainly with respect to the syneresis process.
The protocols for the manufacture of the principal families of cheese are summa-
rized in Chap. 3.

2.5.4 Removal of Whey, Moulding and Pressing of the Curd

When the desired degree of syneresis has been achieved and in some cases, the
desired pH attained also, the curds are separated from the whey by a variety-specific
method, e.g., transferring the curds-whey into perforated moulds (common for soft
varieties, e.g., Camembert), allowing the curds to settle in the vat and sucking off the
supernatant whey (eg., Gouda and Emmental), scooping the curds from the vat using
heavy cloths and placing them in moulds (e.g., Parmigiano Reggiano), draining the
whey form the curds using perforated screens (e.g., Cheddar and Pizza cheese).
Many cheeses are made into traditional shapes and sizes, eg., small flat cylinders
(e.g., Brie and Camembert), taller cylinders, ranging in size from 5 to 40 kg (e.g.,
Cherddar and Parmesan), large low cylinders (e.g., Emmental), spheres (Edam). In
some cases the traditional shapes have been abandoned, e.g., Cheddar and Emmental
now frequently made as rectangular or square blocks.
In some cases, the size and shape of a cheese are cosmetic and traditional but the
size of a cheese has important consequences for the ripening of many varieties.
Surface-ripened varieties, e.g., Camembert, must be small since the surface
microflora plays a critical role in ripening but are effective over only a short dis-
tance. The opposite is required for varieties in which eyes develop due to the propi-
onic acid fermentation, e.g., Emmental, which must have a close texture and large
enough to retain sufficient CO2 for eye development, For an 80 kg Emmental cheese,
120 L of CO2 are produced during maturation, 60 L remain dissolved in the cheese
body, 40 L diffuse out of the cheese and 20 L are in the eyes.; too much CO2 will be
lost from a small or open cheese and eye formation will be poor or absent. A selec-
tion of cheese shapes is shown in Fig 2.5.
Curds for high-moisture cheeses form a congealed mass under their own weight
but the curds for medium- and especially for low-moisture cheese must be pressed
to form a well-matted body, e.g., Cheddar cheese is pressed at 2.7 kPa. As well as
consolidating the curd mass, pressing removes some whey, eg., for Cheddar cheese,
~1.3 % of the volume of milk used is in the press whey.

2.5.5 Special Operations

The curds or pressed cheese curd for certain varieties are subjected to specific treat-
ments to induce a characteristic texture or physico-chemical property or to induce
the growth of certain microorganisms. Examples of such varieties are Cheddar,
Pasta Filata, washed-curd varieties or Blue cheeses.
22 2 Overview of Cheese Manufacture

Fig. 2.5 Examples of the shape of cheese

2.6 Ripening 23

2.5.6 Salting

Salting is the last manufacturing operation. Salting promotes syneresis but it is not
a satisfactory method for controlling the moisture content of cheese curd which is
best achieved by ensuring that the degree of acidification, heating and stirring in the
cheese vat are appropriate to the particular variety. Salt has several functions in
cheese, which are described in Chap. 9. Although salting should be a very simple
operation, quite frequently it is not performed properly, with consequent adverse
effects on cheese quality.
A low level of Na is essential in the diet (the RDA in the USA and UK is 2.4 g)
but an excessive intake is undesirable. Although cheese contributes relatively little
NaCl, even with a high consumption of cheese (consumption of 20 kg of cheese,
containing 2 % NaCl, per annum, which is at the upper level of consumption, con-
tributes 400 g NaCl per annum, i.e., about 1.1 g NaCl or 0.7 g of sodium daily),
there is a commercial incentive to reduce the level of salt in cheese. Approaches are
discussed in Chap. 9.

2.5.7 Application of Ultrafiltration in Cheesemaking

Since cheese manufacture is essentially a dehydration process, it was obvious that

ultrafiltration would have applications in cheese manufacture, not only for standard-
izing cheese milk with respect to fat to casein, but also for the preparation of a
concentrate with the composition of the finished cheese, commonly referred to as
“pre-cheese”. Standardization of cheese milk by adding UF concentrate (retentate)
is now common but the manufacture of pre-cheese has to date been successful com-
mercially for only certain cheese varieties, most notably UF Feta and Quarg. It
seems very likely that ultrafiltration will become much more widespread in cheese
manufacture, perhaps for the production of new varieties rather than modifying the
process protocol for existing varieties.

2.6 Ripening

Fresh cheeses constitute a major proportion of the cheese consumed in some coun-
tries. Most of these cheeses are produced by acid coagulation and are described in
Chap. 16. Although rennet-coagulated cheese varieties may be consumed at the end
of manufacture and a little is (e.g., Burgos cheese), most rennet-coagulated cheeses
are ripened (cured, matured) for a period ranging from ~3 weeks to >2 years; gener-
ally, the duration of ripening is inversely related to the moisture content of the
cheese. Many varieties may be consumed at any of several stages of maturity,
depending on the flavour preferences of consumers and economic factors.
24 2 Overview of Cheese Manufacture

Although curds for different cheese varieties are recognizably different at the end
of manufacture (mainly as a result of compositional and textural differences arising
from differences in milk composition and processing factors), the unique character-
istics of the individual cheeses develop during ripening as a result of a complex set
of biochemical reactions. The changes that occur during ripening, and hence the
flavour, aroma and texture of the mature cheese, are largely predetermined by the
manufacturing process, i.e., by composition, especially moisture, NaCl and pH,
level of residual coagulant activity, the type of starter and in many cases by a sec-
ondary inoculum added to, or gaining access to, the milk or curd.
The biochemical changes that occur during ripening are caused by one or more
of the following agents:
• coagulant
• indigenous milk enzymes, especially proteinase and lipase, which are particu-
larly important in cheese made from raw milk
• starter bacteria and their enzymes
• secondary microorganisms and their enzymes
• non-starter lactic acid bacteria
The secondary microflora may arise from the indigenous microflora of milk that
survive pasteurization or gain entry to the milk after pasteurization, e.g., some
mesophilic Lactobacillus spp. especially Lb casei and Lb paracasei, and perhaps
Pediococcus and Micrococcus. They may also be added as a secondary starter, e.g.,
citrate-positive Lactococcus or Leuconostoc spp. in Dutch-type cheese,
Propionibacterium in Swiss cheese, Penicillium roqueforti in Blue varieties, P. cam-
emberti in Camembert or Brie, or Brevibacterium linens in surface smear-ripened
varieties, e.g., Tilsit and Limburger. In many cases, the characteristics of the fin-
ished cheese are dominated by the metabolic activity of these secondary
microorganisms.
The primary biochemical changes involve catabolism of residual lactose and per-
haps citrate, lipolysis and proteolysis but these are followed and overlapped by a
host of secondary catabolic changes to the compounds produced in these primary
pathways, including deamination, decarboxylation and desulphurylation of amino
acids, β-oxidation of fatty acids, catabolism of lactic acid and even some synthetic
reactions, e.g., esterification.
Although it is not yet possible to fully describe the biochemistry of cheese ripen-
ing, very considerable progress has been made on elucidating the primary reactions
and these will be discussed in Chap. 12.

2.7 Processed Cheese Products

Depending on culinary traditions, a variable proportion of mature cheese is con-

sumed as such, often referred to as “table cheese”. A considerable amount of natural
cheese is used as an ingredient in other foods, e.g., Parmesan or Grana on pasta
2.8 Whey and Whey Products 25

products, Mozzarella on pizza, Quarg in cheesecake, Ricotta in ravioli. A third

major outlet for cheese is in the production of a broad range of processed cheese
products which in turn have a range of applications, especially as spreads, sandwich
fillers or food ingredients. These products are discussed in Chaps. 17 and 18.

2.8 Whey and Whey Products

Only about 50 % of the solids in milk are incorporated into cheese; the remainder
(90 % of the lactose, ~ 20 % of the protein and ~10 % of the fat) are present in the
whey. Until recently, whey was regarded as an essentially useless by-product, to be
disposed of as cheaply as possible. However, in the interest of reducing environ-
mental pollution, but also because it is now possible to produce valuable food prod-
ucts from whey, whey processing has become a major facet of the total cheese
industry. The principal aspects of whey processing are discussed in Chap. 22.