Pasteurization is the process of heat processing a liquid or a food to kill pathogenic bacteria to make the food safe to eat. The use of pasteurization to kill pathogenic bacteria has helped reduce the transmission of diseases, such as typhoid fever, tuberculosis, scarlet fever, polio, and dysentery.
2. DEFINITION
Pasteurization is a type of
sterilization which is used to kill all
the pathogenic micro-organisms
present in the food product.
3. HISTORY OF PASTEURIZATION
• It was invented by French scientist Louis Pasteur during
the nineteenth century. In 1864 Pasteur discovered
that heating beer and wine was enough to kill most of
the bacteria that caused spoilage, preventing these
beverages from turning sour. The process achieves this
by eliminating pathogenic microbes and lowering
microbial numbers to prolong the quality of the
beverage. Today, pasteurization is used widely in
the dairy industry and other food processing industries
to achieve food preservation and food safety.
4. METHOD OF PASTEURIZATION
HTST (High Temperature Short Time )
LTLT(Low Temperature long time)
UHT(Ultra High Temperature)
5. LTST
The batch method uses a vat pasteurizer which
consists of a jacketed vat surrounded by either
circulating water, steam or heating coils of water or
steam. In the batch method, fluid milk is placed in a vat
pasteurizer, which consists of a vat surrounded by
either circulating water, steam or heating coils of water
or steam. To cool the milk, either the milk is allowed to
cool in the vat or the milk is removed from the vat..
The batch or low-temp-long-time or holder
pasteurization (LTLT) process is the traditional method
of pasteurizing milk
In the vat the milk is heated to 62.8 C and held for
30 minutes followed by rapid cooling.
6. HTST
In the continuous flow for high temperature, short time is
flash-heating milk is forced between metal plates or through
pipes heated on the outside by hot water. While flowing under
pressure, the milk is held at 72°C for at least 15 seconds.
Before being chilled back to 4°C or cooler, it flows through a
heat exchanger to pre-warm cold milk just entering the system.
(HTST) pasteurized milk typically has a refrigerated shelf of
two to three weeks (HTST) cause less damage to the nutrient
composition and sensory characteristics of foods than do the
low-temperature, long-time treatments.
This is better than the old way at preserving the nutrients and
quality of foods
HTST plate pasteurizer from 72°C (162°F) to 95°C (203°F)
For 15 seconds..
7. UHT
• Ultra-high temperature processing (UHT)
sterilizes food by heating it above 135 °C
(275 °F) – the temperature required to
kill spores in milk – for 1 to 2 seconds.UHT is
most commonly used in milk production, but
the process is also used for fruit juices, cream,
soy milk, yogurt, wine, soups, honey, and
stews.UHT milk was first developed in the
1960s and became generally available for
consumption in the 1970s.
8. OTHER PROCESSES USED TO
PASTEURIZED FOODS
• Ultra pasteurization - This involves the heating of milk and
cream to at least 280° F (138° C) for at least 2 seconds, but
because of less stringent packaging, they must be
refrigerated. The shelf life of milk is extended 60 to 90
days.
• Steam Pasteurization- This system used a chamber that
exposes the beef to pressurized steam for approximately 6
to 8 seconds. The steam raises the surface temperature of
the carcasses to 190° to 200° F (88° to 93°C).
• Irradiation Pasteurization - Foods, such as poultry, red meat,
spices, and fruits and vegetables, are subjected to small
amounts of gamma rays. This process effectively controls
vegetative bacteria and parasitic foodborne pathogens and
increases the storage time of foods.
9. Different types of foods pasteurization
• Dried Eggs - If eggs are sold dried, the egg white with the
glucose removed is normally heat-treated in the container
by holding it for 7 days in a hot room at a minimum
temperature of 130°F (54°C).
• Whole Eggs Pasteurized in the Shell - Traditionally, eggs
sold to customers in the shell have not been pasteurized.
Egg whites coagulate at 140°F (60°C). Therefore, heating
an egg above 140°F would cook the egg.
• Milk - Pasteurization improves the quality of milk and milk
products and gives them a longer shelf life by destroying
undesirable enzymes and spoilage bacteria. For example,
the liquid is heated to 145°F (63°C) for at least 30 minutes
or at least 161°F (72°C) for 15 seconds.
11. Pasteurization of Fruit Juice
• Pasteurization is a process by which foods are heated to a specific
temperature for a specific amount of time to kill (or deactivate) a
target number of potentially harmful bacteria. Many different
products sold in the supermarket may be pasteurized, including
milk, fruit juices, almonds, cider, and beer.
• The United States Food and Drug Administration (FDA), through its
Center for Food Safety and Applied Nutrition (CFSAN), sets detailed
guidelines for the pasteurization of fruit juices. For example, for
apple juices with a pH level of 4.0 or lower, the FDA recommends
heating processes that "achieve a 5-log reduction for oocysts of
Cryptosporidium parvum ." These heating processes vary in length
of time from 0.3 to 6.0 seconds, with heating temperatures
between 160-180°F.
12. PASTEURIZATION OF EGG
Pasteurized eggs are eggs that have
been pasteurized in order to reduce the risk of
food-borne illness in dishes that are not
cooked or are only lightly cooked. They may
be sold as liquid egg products
or pasteurized in the shell.
13. PASTEURIZATION OF CURD
• The cheeses that were characterized by the
scalding of curd in hot whey were
manufactured from raw or pasteurized milk
and the curds were scalded in hot whey at 60,
70, 80 or 90 °C. Differences in the levels of pH
4.6-soluble nitrogen between cheeses were
significant (P < 0.05) after 30 days of ripening
14. CONSUMER ACCEPTANCE
• Although pasteurization has been practiced for a
long time, some consumers contend that they
should have the right to buy and sell
unpasteurized milk if they want to.
• Some consumers also point out that government-
enforced pasteurization law has been used as a
tool for large business to shut out competition
from smaller producers. See the case of the FDA's
shut down of Good flow Juice in 2008
15. PRODUCTS THAT ARE COMMONLY
PASTEURIZED
• BEER
• EGG
• WINE
• MEAT
• VINEGAR
• JUICE
• WATER
• DIARY PRODUCT
• SYRUP