Dairy Technology

1. Milk processing

Milk processing
Milk processing involves the basic processes of storage, separation, homogenization and pasteurization. These
processes also play a major role in
yogurt, butter and cheese making.
Precedence is therefore given to them
on the following pages as the standard
processes of dairy technology.
The process of yogurt production is described as typical for the preparation of
fermented products. The use of different bacterial cultures, for example, or
changing the sequence of the sub-processes produces semi-solid yogurt or
drinking yogurt.
Cheese products are also presented
typically for all common varieties of
cheese. Not every process is used
for every product. Quark and cream
cheese require pasteurization, for example, but these types do not undergo
ripening. Again, for other sorts of
cheese, such as pasta filata varieties,
the cheese curd is subjected to a cooking and stretching process to obtain an
elastic-textured cheese.

1.1. Homogenization

Homogenizing
Accurate pressure control and monitoring during homogenization guarantees
that this process is always performed
efficiently enough to achieve the desired
result. In cream production, for example,
homogenization sets the viscosity. Using
JUMO IMAGO 500 process and program
controller to control the pressure variable during this part of production is the
easiest solution. This makes it possible
to connect several homogenizers immediately.

1.2. Pasteurization/Heat treatment

Pasteurizing/
heat treatment
Monitoring temperature
with the JUMO LOGOSCREEN nt
The JUMO LOGOSCREEN nt is ideally
suited for recording the temperature
during pasteurization. The instrument
meets the guidelines laid down by the
Heating Committee with regard to measurement, control and safety equipment
for milk heating systems. (EU regulation EC Nos. 852/2004 and 853/2004).
Equally impressive is the high enclosure
protection provided by the JUMO LOGOSCREEN nt stainless steel case. 

2. Yogurt production process

Yogurt production
Yogurt production is used as an example
of production for all fermented products.
The yoghurt type defines the standardized fat content of the processed milk.
It does not matter whether you are making semi-solid yogurt, stirred yogurt,
drinking yogurt or another fermented
product such as sour cream, creme fraiche, kefir, buttermilk or sour milk, the
core process is the same.
The milk is adjusted to the required fat
content for the desired end product.
After homogenization and pasteurization the bacterial culture specific to the
particular product is added to the milk
and incubated.
Once products reach the optimum pH
value they are cooled, a fruit mixture is
added if required and then filling takes
place. This is usually under aseptic conditions to avoid recontamination.

2.1. Evaporation

Evaporation
Monitoring the increase in
dry matter by temperature
The fat content and dry matter of the
milk used in yogurt production are
standardized. Standardizing the dry
matter improves the yogurt gel. There
are various ways to perform this standardization. The most common way is
to increase the dry matter of the milk
by evaporation in a vacuum chamber.
This process is monitored by means of
the temperature at inflow. The degree
of evaporation is determined by the distance covered by the heated milk in
the evaporator. 

2.2. Fermentation

Fermentation
Monitoring of
fermentation/incubation
Once the relevant yogurt culture has
been added to the milk, incubation follows.
The end of the incubation phase is
often controlled by the pH value. As
soon as the pH value reaches 4.2 to 4.5,
the yogurt must be cooled from the incubation temperature to between 15°C
to 22°C so that acidification is stopped.
JUMO tecLine pH electrodes in a hygienic process fitting can safely monitor
this process. 

3. The Cheese production process

Cheese production
The simplified cheese production
process depicted here is used as an
example of all common cheese varieties (whether hard cheese, cheese
slices, soft cheese, cream cheese or
quark). Of course, the production processes do vary. With quark and cream
cheese, for example, there is no ripening.
Once the milk is delivered, if it cannot be
processed immediately, it is first thermized. Thermization slows down bacterial
growth, thus allowing for a longer processing time.
Depending on which cheese is being
made, before curdling, the milk is standardized, pasteurized and even sometimes, for special semi-soft cheese
slice varieties, partly homogenized.
In the cheese making machine curdling
is achieved by relevant bacterial cultures
or rennet. The cheese curd is then cut up
with a so-called cheese harp to make it
easier for the whey to escape. After the
whey has escaped the cheese curd is
shaped, pressed, salted and stored for
ripening.

3.1. Cheese vat

Cheese vat
pH value and temperature control
in the cheese vat
The pH value and temperature in the
cheese vat have to be controlled and
recorded. The two measurement variables are parameters for the later quality
of the cheese and determine the steps
of the process that are to follow. For example, the duration of the stirring period
depends on the required level of acidity.
The temperature/time diagram is determined by the method of heating and
the variety of cheese. The combination
of a hygienic temperature probe and the
JUMO dTRON compact controller allows
fast temperature recording and optimized control. This also makes it possible
to save energy, as unnecessarily long
switching and heating periods are avoided.

3.2. Salting and Ripening

Salting
Measuring salt concentration in the salt
bath via conductivity with the JUMO CTI750. There are several reasons for salting the cheese loaf, the most important
being to achieve the right product consistency. During this process sodium
from the salt is deposited in the cheese,
which consistently changes the concentration of salt in the brine. The process
must be monitored. This can be done
with the JUMO CTI-750 inductive conductivity transmitter. The temperature is
measured at the same time, as the duration of the cheese loaf in the brine also
depends on this process variable

Ripening/ storage
Monitoring temperature and moisture
during ripening is important.
Different storage conditions are required
for different cheese varieties.
The important measurement variables
during ripening are temperature, relative
humidity and time.
To ensure optimum and reproducible
ripening those measurement variables
must be continually monitored and recorded.