The document discusses food preservation techniques, which extend the shelf life and maintain the quality of food products. It covers various methods such as drying, canning, freezing, and pickling, as well as the principles of inhibiting microbial growth and chemical reactions. Additionally, it highlights the importance of food processing methods that enhance flavor, nutritional value, and prevent spoilage for commercial benefits.

1. Food Processing, Preservation
and Shelf-Life Study

3. Introduction
I want eat a mango in
winter season? Is it
possible? Why not ! it is possible

4. Food Preservation
Food Preservation is a process in which
Food and vegetables are prevented from getting
spoilt
The color, test, and nutritive values of food is also
preserved
Food products lasts for a long period of time:
Shelf life of food product is increased

5. Types of foods
Food Types
Perishable Semi Perishable Shelf Stable
Fruits Milk Cheese, Some
ready foods
Grains

6. Food types
Perishable
- Lasts for less time 2 days to 1week
- Example: Fruits, milk, vegetables,meat
Semi perishable
- Lasts for around 2 months and are processed
- Example: Ice-cream, cheese, bread,cake, pastries
Shelf Stable
- Has longer shelf Life more than 6 months
- Example: Food grains

7. Principles of Food
Preservation
1. Inhibit the growth and activity of Microorganisms
-Asepsis(to keep outmicroorganisms)
-Removal of microorganisms
-Stopping the growth and activity of microorganisms
(low temperatures, drying or chemicals)
-Destruction of MO(heating or radiation)

8. Principles of Food
Preservation(contd.)
2. Protecting against self decomposition of food
-Inhibit the activity of Endogenous Enzyme
(Phenolase)
-Delay or inhibit chemical reactions(Non-enzymatic
browning)
3. Protection from invasion and spoilage by insects and
rodents
4. Protection against losses by mechanical causes

9. Food Preservation
Methods
Preservation methods vary according to
--------the food items, and
--------quantity of the items to be preserved
Principles of Food preservation can be broadly
classified into twotypes:
1) Bactericidal methods
2) Bacteriostatic methods

10. Bactericidal
methods:
Most of the microorganisms are killed
Examples are-
o cooking,
o canning,
o pasteurization,
o sterilization,
o irradiation etc.

11. Bacteriostatic Methods:
Based on prevention of multiplication of
microorganisms
May be achieved by
----removal of water
----use of acids, oils or spices
----keeping thefoodstuff in low temperature
Methods based on this principles are
----Drying,
----freezing,
----pickling,
----salting, and
----smoking.

12. Techniques of Food Preservation
Physical
Chemical
Physical
--freezing and canning(rely on killing
the microorganisms or at least stopping
the their growth for long enough)
--drying, gamma irradiation, exposure to
ultraviolet or high intensity white light,
ultra high pressure and filtration

13. Chemical
Preservatives
Work either as:
 Direct microbial poisonsor,
 Reducing the pH to a level that prevents the growth of
MOs
#Chemicals used todayare:
1. Nitrates and Nitrites
----to preserve meats
2. Sulphites
----to prevent the browning of fruits and vegetables,
----to prevent fungalspoilage

14. Common food preservation
methods:
Bottling and canning
Pickling
Drying
Salting
Vacuum packing
Cooling and freezing
Waxing
Pasteurization
Boiling

15. Bottling and Canning
Bottling and canning are processes of
preserving food by heating and then
sealing it in an airtight container.
The food is boiled to kill microorganisms
and then sealed to prevent other
microorganisms from getting in.

16. Bottling Canning

17. PICKLING
Pickling food in vinegar or other acids, makes
it difficult for microorganisms to live.
Commonly pickled food include onions,
parkias, soya beans and chillies.
Sugar can also be used in pickling fruits such
as nutmegs, mangoes and cherries.

18. The concentrated sugar solution used draws
water from the fruit thus preventing the
growth of microorganisms.

19. Drying
Alot of food is preserved by drying under the
sun.
Drying removes most water from food. Most
bacteria die or become inactive when the
food is dried.

20. Anchovies and dried chillies are examples of dried
food

21. Alot of fruits such as raisins, guavas
and papayas can be eaten dried.

22. Salting
Salting is an age-old way of preserving
food. The salt draws out moisture and
prevents microorganisms from
growing. In this process, food such as
fresh fish are washed and coarse salt
is rubbed into it.

23. A lot of our local foods are
preserved by salting process.

24. Vacuum Packing
Vacuum packing keeps food by sucking
air out from its packaging.
Food is thus prevented from spoiling
because there is no air.

25. Vacuum packing is commonly used for storing
nuts, sliced fish, pickled and dried fruit.

26. Cooling and Freezing
Cooling and freezing are the most
common forms of food
preservation.

27. Cooling slows down the action of
microorganisms, thus it takes longer
to spoil. It allows fruit from different
parts of the world to appear on our
supermarket shelves.(0 to -40 C)
At freezing temperature,
microorganisms become inactive,
thus food cannot spoil when it is
frozen. (-18 0C)

28. Food like meat, fruit and vegetables are kept in
the refrigerator.

29. Waxing
Waxing of fruit and vegetables is also common. Apples,
oranges, eggplants and tomatoes are dipped into liqiud
wax to prevent growth of fungi and loss of moisture.
Waxed fruit need to be washed thoroughly or peeled before
eating.

30. Pasteurization
Pasteurization means heating food to a
certain temperature for some time
followed by rapid cooling. Heating at
such high enough temperature kills
most bacteria. However, it does not
affect the taste and nutritional value of
the food.

31. Fresh milk, yoghurt drink and juices are
pasteurized to make them last longer.

32. Boiling
As food is heated and cooked, the heat kills the
microorganisms,
Boiling kills most bacteria. However, those not affected by
heat will grow when the conditions are suitable.
Boiling kills bacteria

33. Smoking
Smoking is the process of drying food with
smoke for a long period of time. This
method is mainly used for fish, meat and
fruit such asbanana.
The drying effects of smoke and the chemicals
produced from the smoke help to preserve
the food.
Smoked banana smoked meat

34. Food Processing
From Farm ToTable
?
Whey protein, a by-product
of cheese manufacturing, is
used in energy bars and drinks!

35. Aims of Food Processing
1.To extend the shelf life to allow time for distribution,
sales and home storage.
2.To increase variety in the diet by providing a range of
attractive flavours, colours, aromas and textures in food
(collectively known as eating quality, sensory
characteristics or organoleptic quality); .
3.To provide the nutrients required for health (termed
nutritional quality of a food).
4. To generate income for the manufacturing company.

36. Food Processing
Examples of food processing methods include:
Chopping
Mixing
Homogenizing
Cooking
Pastuerizing
Blanching
Spray-drying
Frying
Baking
Packaging

37. Dehydration
Dehydration (or drying) is defined as ‘the application
of heat under controlled conditions to remove the
majority of the water normally present in a food by
evaporation’ (or in the case of freeze drying by
sublimation).
The main purpose of dehydration is to extend the shelf
life of foods by a reduction in water activity This
inhibits microbial growth and enzyme activity, but the
processing temperature is usually insufficient to cause
their inactivation.

38. Dehydration
Drying causes deterioration of both the eating quality and
the nutritional value of the food.
Examples of commercially important dried foods are
coffee, milk, raisins, and other fruits, pasta, flours
(including bakery mixes), beans, nuts, breakfast cereals,
tea and spices.
 There are a large number of factors that control the
rate at which foods dry, which can be grouped into the
following categories
processing conditions
nature of the food
drier design.

39. Blanching
A few processed vegetables, for example onions and green
peppers, do not require blanching to prevent enzyme
activity during storage, but the majority suffer considerable
loss in quality if blanching is omitted or if they are under-
blanched.
To achieve adequate enzyme inactivation, food is heated
rapidly to a pre-set temperature, held for a pre-set time and
then cooled rapidly to near ambient temperatures.
The factors which influence blanching time are:
• type of fruit or vegetable
• size of the pieces of food
• blanching temperature
• method of heating.

40. Pasteurisation
Pasteurization is a relatively mild heat treatment, in which
food is heated to below 100ºC. In low acid foods (pH>4.5,
for example milk) it is used to minimize possible health
hazards from pathogenic micro-organisms and to extend
the shelf life of foods for several days.
In acidic foods (pH <4.5, for example bottled fruit) it is
used to extend the shelf life for several months by
destruction of spoilage micro-organisms (yeasts or moulds)
and/or enzyme inactivation

41. Canning
A method of preserving food by killing all
microorganisms present in the food and then sealing
out air
The food, container, and lid are heated until sterile
As the food cools, the lid makes an airtight seal,
preventing contamination

42. Extrusion
Aprocess by which the form of a food is changed
Such as changing corn to corn chips
Not a preservation measure
In this process, the food is heated, ground, and pushed
through various kinds of screens to yield different
shapes

43. Irradiation
Ionising radiation takes theform of Gama-rays
from isotopes or, commercially to a lesser extent,
from X-rays and electrons. It is permitted in 38
countries to preserve foods by destruction of
micro-organisms or inhibition of biochemical
changes.

44. Chilling
Chilling is the unit operation in which the temperature
of a food is reduced to between 1ºC and 8ºC.

45. Packaging
Food is packaged for many purposes.
 Some reasons are:
containment for shipping, dispensing, unitizing in to
appropriate sizes, improving the usefulness,
protect from microbial contamination, physical dirt, insect
invasion, light exposure, flavor pickup, flavor loss,
moisture pickup, moisture loss and physical abuse
Food is packaged in metal cans, glass & plastic bottles,
paper &paper board, wide variety of plastic &metallic
films andcombinations of these
 Packaging is done by continuous automatic machines at a
speed of 1000 units permin
 The container forming is dependent on the type of the food