food knowledge food Food_preservation.ppt

HELE

1. It means to increase the shelf life so that we can use it in
future .
It is the method to preserve spoilage
It is method of treating food to prevent or to delay spoilage

2. Prevent the growth of micro organism
Improve the shelf life of food
Making seasonal fruits and vegetables throughout the year
Add variety to the diet/ menu
Save time and energy
Add nutritive value to diet
Cost control

3. Food Preservation
Chemical
Low
temperature
High
temperature
Irradiation
Refrigeration Freezing
CanningPasteurisation Smoking Dehydration

4. Bacteriostatic-these are the technique which does not allow microbes to
grow in nosby creating adverse condition. e.g. changes in PH, removal
of moisture, use of natural preservative and use of chemical preservative
Bactericidal-these food preservation techniques cause damage to
microbes. There by killing or destroying them. They are use of high
temperatures, use of low temperature or Irradiation.

5. Microbes required moisture for there growth
If water is removed from food then spoilage causing microbes can’t
grow
Above this dehydrated food is easy to handle & stored as removal
of water causes considerable loss in wtas well as volume of food
E.gmilk powder, kasurimethi
Drying and dehydrating is done by
Sun drying-food is exposed to sun rays due to which moisture
evaporates.e.gpapad, fish, raw mangoes
Air drying-food is placed on conveyor and hot air blond over the food which
leads to loss of moisture
Oven drying-food is placed in hot chamber which leads to loss of moisture
Freeze drying-food is stored very low temperature. It is -20c this causes
loss of moisture

6. Class I preservative(natural preservative)
Common salt,Sugar, Dextrose, Glucose (syrup), Spices ,
Vinegar or acetic acid, Honey ,Edible vegetable oils
There are common theories to explain preservative action of salt
›It stops poisonous action
›It makes moisture unavailable for the microbes
›It prevents bacterial growth by dehydrating the cells
›It destroys bacterial living cell

7. Propionates-sodium & potassium propionate added to bread
dough to prevent growth of mould & extends shelf life of baked
product
Sorbates–pottasiumsalt of sorbicacid is added to acidic foods
to prevent growth of fungi or yeast in acidic products like apple
juice and also sorbicacid is used in wrapper of cheese to prevent
growth of mould
Benzoates-used to preserve sauces, fruit products and jams
Sodium chloride –salt when added to adequate concentration
helps to preserve food & control microbes
Citric / acidic/ lactic & phosphoric acid-these occurs naturally in
fermented food & have greatest preserving power

8. Storage food below 4C
Perishable food like raw meat, poultry, fish, stocks, soups,
gravies, dairy products, fruits and vegetables
Retards bacterial growth but can’t undo any damage already
done.

9. Deep Storage -temp below -6C to -25C or lower
Blast freezer –temp may be lower -35C
Temp being so low food turns into ice & maintained in that
state. This preserves colour and flavours of food better than
refrigeration
This is used to preserve large amount of food stuff for longer
period time

10. It is a process of heating food which is usually a liquid to a
specified temperature & times and then immediately cooling it
after it is removed from heat.
This process slows down spoilage caused by microbial growth in
food. Example, milk
1.Low temperature high time(LTHT)-62C for 30 mins
2.High temperature low time (HTLT) –72C for 15 mins
3.Ultra high temperature (UHT)-above 135C for 2 sec

11. The preservation of food in sealed container by sterilizing the
food with the help of heat is called canning.
Fruits, vegetables, meat, seafood, soups, baby-food, juices
are preserved by canning.
The characteristics of an ideal container for canned foods are
1.It should be strong enough to protect content during shipment(
transportation)
2.Light enough for easy handling
3.Readily openable
4.Incapable to air and water
5.Should not react with food
6.Capable of being heated for sterlizatio

12. It is a term referring to any process that eliminates
(removes) or kills all forms of microbial life including
transmissible germs found/present on the surface.
Sterilization can be achieved by applying heat,
chemicals, irradiation , high pressure and filtration or
combination wear off.

13. This is one of the beneficial applications of atomic energy and is
an important innovation in food preservation.
Exposure of food material to radiation has strong advantage over
conventional methods of preservation because it does not lead to
loss of flavors, odor, texture or quality.
The process involves the controlled application of energy from
radiation such as gamma rays, x-rays, accelerated electrons.
Irradiation is a direct, simple and efficient one-time process.
Application of doses of radiation can arrest the sprouting of
potatoes and onions.

14. It appears that compounds present in wood smoke have
antibacterial action that prevent the growth of organisms that
cause spoilage.
It was discovered by early humans that certain food such as
meat, fish, cheese, etc when exposed to smoke last longer
than those that are not.