International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 5, Issue 4, April 2015)
Automated Pasteurizer Unit for On-Farm Pasteurization of
Milk.
Mahesh Chitnis1, Saiprasad Bhatawdekar2, A. A. Shinde3
1,2,3
AISSMS IOIT
Abstract— The main aim of this project is to design a
portable automated batch pasteurizer in order to process the
milk on or near the site, thus ensuring safe supply of milk for
human consumption. The system uses High Temperature,
Short Time (HTST) method for pasteurization of milk. The
process is controlled by a PLC and also it can be continuously
monitored over SCADA.
There is an apparent need of pasteurizing raw milk on
site to permit its safe use. There is also a need for portable,
simple and economical apparatus for processing milk at or
near the source for both human and animal consumption
[3].
Keywords— Batch Pasteurizer, Extended Shelf Life (ESL),
High Temperature Short Time (HTST), Pasteurization, Ultra
Heat Treatment (UHT) .
Pasteurization is a process invented by French
scientist Louis Pasteur during the nineteenth century.
Pasteur discovered that heating milk to a high temperature
and then swiftly cooling it, enables the milk to remain
fresher for a longer period of time. ESL is achieved by
eliminating pathogenic microbes and lowering microbial
numbers to prolong the quality of the beverage. Today the
process of pasteurization is used widely in the dairy
and food industries for microbial control and preservation
of the food we consume. . Pasteurization is responsible for
the Extended Shelf Life (ESL) of milk.
II. PASTEURIZATION
I. INTRODUCTION
India is the largest producer of milk as compared to
other countries; however modern techniques have not
found much application in the processing of milk. There is
a need of a portable apparatus which can be used to carry
out the pasteurization of milk in order to improve its shelf
life.
Milk is an excellent medium for microbial growth, and
when stored at ambient temperature bacteria and other
pathogens soon proliferate. The US Centers for Disease
Control (CDC) says improperly handled raw milk is
responsible for nearly three times more hospitalizations
than any other food-borne disease outbreak [1]. In India
pasteurization plants have been installed in industries and
government plants, but the bulk of milk is sold in raw
condition.
In an effort to reduce the risk of infection, dairy
producers can implement on-farm pasteurization of milk as
a control procedure before the use of milk. In the present
study, the efficacy of a commercial high-temperature,
short-time (HTST) on-farm pasteurizer unit to
destroy Mycobacterium
paratuberculosis,
Salmonella
enterica spp., and Mycoplasma spp. in raw milk was
evaluated. The results of these tests suggest that HTST
pasteurization is effective in generating a safer product [2].
Dairy farmers and other producers of foodstuffs such as
milk are often required to transport their produce to central
plants for pasteurization. In less advanced countries,
modern processing plants may be unavailable or
inaccessible.
III. EXISTING METHODS
There are various methods available for pasteurization of
milk.
A. Traditional methods
A traditional form of pasteurization of milk existed in
England before 1773, in which pasteurization of milk was
done by scalding straining of cream to increase the keeping
qualities of butter.
B. Modernized Methods
Pasteurization typically uses temperatures below boiling,
since at very high temperatures, casein micelles will
irreversibly aggregate, or "curdle". The two main types of
pasteurization used today are high-temperature, short-time
(HTST, also known as "flash") for an extended shelf life
(ESL). Ultra-high temperature processing (UHT, also
known as ultra-heat-treating) is also used for milk
treatment.
The available modernized methods can be tabulated as
follows;
304
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 5, Issue 4, April 2015)
TABLE I
Methods available for pasteurization of milk
Sr.
No.
1
Method of
pasteurization
HTST
(High
Temperature
Short Time)
Temperature
(in deg. C)
72
2
UHT
(Ultra-HeatTreatment)
138
2s
3
US FDA Legal
Alternative
63
30min
The above figure shows the P and I diagram of an
automated, portable batch pasteurizer.
Process Description: A fixed amount of milk is added
to the vessel. The milk container is surrounded by a water
bath into which an electrical heating coil is inserted. On
start up the electrical heating coil is energized and the
motor connected to the stirrer is activated by a signal from
the PLC. Stirring action ensures uniform heating. This
initiates the heating process.
The temperatures of water bath and milk are
continuously monitored by temperature sensors. RTD’s are
employed for the purpose of temperature measurement. As
shown in the figure, temperature of water bath is indicated
by TI1 and the temperature of milk is given by the TT1.
These signals are given to the PLC for further processing
and taking precise control action.
According to the specifications of the HTST method the
temperature of milk is maintained at 72ᴼC by varying the
electrical supply to the heating coil. The milk is retained in
the tank at this temperature for 15 seconds.
Once the milk has been retained in the pasteurizer, for
15 seconds, at 72ᴼC, the heater coil is turned OFF.
Respective control valves are sequentially opened and
closed, according the process requirements, through the
predefined instructions from the PLC. This drains the hot
water out of the water bath and begins the inflow of cold
water for cooling process. Solenoid valves are used for this
purpose.
Once the hot water has been flushed out cold water is
continuously circulated in the water bath. Raid cooling is
ensured. This will cool the milk to room temperature. Once
the milk cools down to a predefined value, the PLC will
give an output signal to close all the valves and stop the
stirring action. This marks the completion of pasteurization
process and end of on batch.
Time
15s
These are the methods which are currently being used in
the dairy industry. Out of these methods HTST method can
be effectively implemented for a portable and economic
pasteurizer which can be used for the processing of milk on
its site of production.
C. Proposed System:
Flash pasteurization, also called "high-temperature
short-time" (HTST) processing, is a method of heat
pasteurization of perishable beverages like fruit and
vegetable juices, beer, kosher wine, and mainly dairy
products such as milk. We have made an attempt of
designing a portable batch pasteurizer with PLC control
and continuous monitoring over SCADA.
D. Advantages of the proposed scheme:
This scheme provides convenient field pasteurization of
milk, thus improving the shelf life of the milk.
The proposed design can be used with available hot and
cold tap water and electrical current available in dairy
farms located in rural areas.
The pasteurizer unit can be quickly and effectively
cleaned between uses further reducing the risk of health
hazards.
The apparatus is easy to use and can be installed and
used by any ordinary dairyman across the country.
FIGURE I P and I diagram of batch pasteurizer.
305
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 5, Issue 4, April 2015)
[2]
E. Results:
A fixed amount of milk is pasteurized by heating it to
72ᴼC then holding this temperature for 15 seconds followed
by its rapid cooling to room temperature. The HTST
method of pasteurization is followed.
[3]
[4]
[5]
REFERENCES
[1]
http://en.wikipedia.org/wiki/Pasteurization
306
http://www.journalofdairyscience.org/article/S0022-0302(04)700387/abstract?cc=y
Richard Henry Dumm, Aug 2001, Dairy Tech INC , Winsor, CO
(US), Automated Batch Pasteurizer.
http://www.britannica.com/EBchecked/topic/446003/pasteurization
http://agropedia.iitk.ac.in/content/opportunities-and-challengesindian-dairy-industry