Handbook of Food Science and Technology 3

Mass balance, cheese yield and recovery rate
When processing milk into cheese, it is possible to calculate the mass 
balance for a constituent X (protein, fat, etc.) using the following equation: 
{
M
M
C
C
W
W
M
C
W
w X
w X
w X
w
w
w
=
+
=
+
[1.5] 

---

46 Handbook of Food Science and Technology 3 
where w
M
, w
C
and w
W,
and X
M
, X
C
and X
W, 
respectively, are weight (kg) of 
milk, cheese, whey, and concentrations of the constituent X in milk, cheese 
and whey (g kg
-1
). Cheese yield Y
C
(dimensionless) is expressed in kg of 
cheese per 100 kg of milk used. 
c
C
m
w
Y
100
w
=
[1.6] 
By combining [1.5] and [1.6], we get 
M
W
C
C
W
X
X
Y
100
X
X
−
=
−
[1.7] 
For example, if 50 kg of milk with 32 g kg
-1
of protein give 6.7 kg of 
cheese and 43 kg of whey with 185 g kg
-1
and 8.5 g kg
-1
of protein 
respectively, the cheese yield R
F
is equal to 13.3%. To standardize the cheese 
yield calculation, technologists often calculate the yield of a reference cheese; 
this corrected yield (Y
CC
) is: 
M
W
C
W
CC
C
ref
W
ref
W
X
X
X
X
Y
100 Y
100
X
X
X
X
−
−
=
=
−
−
[1.8] 
where X
ref
is the concentration of constituent X in a reference cheese, 
representative of a given technology.
For a given manufacturing process, it is also possible to calculate the 
recovery rate R
X
of a constituent X in cheese based on the following equation: 
C
C
X
M
M
w X
R
100
w X
=
[1.9] 
In the previous example (50 kg of milk with 32 g kg
-1
of protein gives
6.7 kg of cheese with 185 g kg
-1
of protein), the recovery rate of protein R
prot
is 
therefore 77.5%.
Drainage and acidification kinetics: categories of cheese 
The physicochemical properties of cheese during demolding (fat-free dry 
matter – FFDM, fat content, pH, moisture in non-fat substance – MNFS,

---

From Milk to Dairy Products 47 
calcium on a from basis – Ca/FFDM), which determine the ripening process 
by influencing microbial growth and biochemical and enzymatic reaction 
kinetics, depend on the intensity and relative position of the drainage and 
acidification stages (Figure 1.21).
MNFS (dimensionless), which expresses the availability of water in the 
curd, is calculated as follows: 
C
c
100 DM
MNFS
100
100 F
−
=
−
[1.10] 
where DM
C
and F
C
are the dry matter and fat content of cheese,
respectively.
There are four main categories of cheese: 
– 
Acid curd
, such as fresh cheeses: This is high-moisture cheese; in this 
case acidification of the milk substrate precedes drainage. Whey is drawn off 
at acid pH (4.5–5), under conditions where more than 80% of calcium and 
phosphates are solubilized in the whey. This leads to a significant 
demineralization of the cheese, which accentuates its friability and 
crumbliness. 
– 
Rennet curd
, such as semi-hard and hard cheeses (cooked pressed 
cheese): Processing involves intense drainage after rennet coagulation. 
Drainage therefore precedes acidification that occurs in a lactose-depleted 
medium; the buffering capacity is largely due to the concentration of proteins 
and minerals (FFDM up to 30–35%). As a result, the pH of the cheese at the 
end of the acidification stage is generally between 5.2 and 5.4, and its calcium 
content is higher than other types of cheeses (2.9 
<
Ca/FFDM 
<
3.1%). These 
characteristics give an elastic and cohesive texture; the low level of MNFS 
results in a shelf life of several months.
– 
Mixed curd with a predominantly acid nature
,
 
such as traditional and 
industrial soft cheeses: These are high-moisture cheeses (MNFS around 75%), 
relatively acidic before ripening (pH 4.6–4.8) and depleted of minerals. The 
shelf life of these products is no more than a few week.
– 
Mixed curd with a predominantly rennet nature
,
 
such as semi-soft 
cheeses and medium-hard cheeses (stabilized soft cheese, uncooked or semi-
cooked pressed cheese): There is a greater level of drainage compared with

---

48 Handbook of Food Science and Technology 3 
the previous category, which may involve a lactose-removal stage. The pH at 
the end of the acidification stage ranges from 4.8 to 5.2 and the cheese has a 
moderate mineral content. The shelf life is a number of weeks depending on 
the MNFS (60 – 72%).