Ways to preserve food

1. Food preservation
Paper 11: Bioprocess Engineering & technology
(Session : 2020-21)
Guided by:
Mrs. Preeti Verma
Submitted by:
Pushpita Saha
(M.Sc. 3rd Sem(Biotechnology)

2. Introduction
Need for
preservation
Principle
Techniques
of
preservation
Applications
References
Contents

3. Introduction
Mankind developed food preservation
techniques from very ancient times such as
drying, heating, applying salt and sugar etc.
Later the work of Pasteur made possible to
understand and discover new areas and
techniques in food preservation.
Now a days more chemicals and antibiotic is
employed in food preservation in large scales.
It’s a process by which food is prevented from
getting spoiled for a long period.
Techniques in food preservation largely depends
upon the type of food and its spoilage.
https://upload.wikimedia.org/wikipedia/commons/0/06/Female_workers_in_a_Sauerkraut_factory_in_Germany_in_1918.jpg
Fig 1

4. https://media.springernature.com/original/springer-static/image/chp%3A10.1007%2F978-3-030-11530-2_3/MediaObjects/421695_1_En_3_Fig1_HTML.png
Fig 2

5. Need for food preservation
• FOOD CONTAMINATION
It’s the presence of harmful chemicals or toxins and microbes in food
that can cause illness, if consumed.
• FOOD SPOILAGE
Process by which food products become unsuitable to ingest by
consumer.
Causes- Physical, chemical and biological factors .

6. Principle
1.Preventionof
microbial
decomposition
3.Asepsis
2.Delayinself-
decomposition
offood
• Delay in microbial growth
• Removal of microbes
• Hindering microbial growth
• Killing of microbes
• Destruction of food
enzymes
• Delay in chemical
reactions
• It means keeping out
microbes as a
preservative factor
• Protective covering
delays the degradation of
food
• Food packaging

7. FOOD PRESERVATION TECHNIQUES

8. 1. Using High Temperature

9. 1. Using High Temperature
• One of the safest, reliable and most common
methods
• Heat treatment selected is based on:
1. Kind of organism to be killed
2. Effect of heat on food
3. Other preservative methods employed.
PRINCIPLE :
Heat destroys vegetative cells as well as viable spores
by inactivation of enzymes required for their
metabolism or by merely killing them.

10. https://s3-us-west-2.amazonaws.com/courses-images/wp-
content/uploads/sites/1950/2017/05/31183742/px-bacterial-growth-
en.svg_.png
https://lh3.googleusercontent.com/proxy/l5rgnIJCStrBJ2m5Jg2kieGZ5AjXtY6oAdmP2xsUyqjj1q
uiGL7rhsok4HfGpGPw_2fDlrhe_M4OqVKugYxM2TqotY2H6J2p5SklcK28-
FFM5QiovW1RD1WEJSTg4VUHW4pXCriMborrkQGH_MbIlvA
Microbial Growth Curve
Graph 1
Graph 2

11. Thermal death time (TDT)
2. Initial concentration
of spores/cells
More conc. of cells require more heat.
4. Composition of
medium where cells are
heated
• Moist heat more effective
• pH
• Sugars, Salts present
• Use of Hydrogen peroxide
1. Time
Time for killing microbes decreases as
increase in temperature.
3. Previous history of
cells or spore
Conditions where cells are grown
influence their heat resistance..
 TDT is the duration of a specific microorganism to die or get inactivated by thermal
processes
 It differs from one to another microbe.
 Chief factors governing TDT are:-

12. How to determine Thermal processes ?
01
02
03
01
02
03
TDT CURVE
Knowledge of heat rrsistant microbes in
food is very essential.
HEAT PENETRATION
Knowledge of size and type of container is
necessary as well as the type of food.
CALCULATION OF PROCESS
TIME
Calculated by a formula.

13. 1. TDT CURVE
 Requires complete knowledge of the bacteria or its spores
 The TDT curves are plotted in semilogarithmic paper called as Growth
no growth method
12D CONCEPT
Classical values of TDT with 6 X 10¹°
spores of Clostridium botulinum was
done by Esty and Meyer(1992) and
reduced them to 0.1 spore by
heating at 150F for 2.78 minutes.
Graph 3

14. 2. HEAT PENETRATION
Material
of
container
Size and
shape
of the
container
Food
Consisten
cy
Initial
Food
temperat
ure
Agitation
It depends upon the following factors:-

15. 3. CALCULATION OF PROCESS TIME
To calculate time in mins(t) to destroy a certain no. of cells / spores by heating at ‘T’
Temperature where,
z is degrees of Fahrenheit required reduce the TDT ten folds
F is the time to destroy a cell at specific medium in 121.1°C or 250F
Knowing values of z & F, the formula is:
Log t – log F
log 10
=
𝟐𝟓𝟎 − 𝐓
𝐳
t =
𝐅 𝐚𝐧𝐭𝐢𝐥𝐨𝐠 𝟐𝟓 𝐓
𝐳

16. Heat treatments employed in
food processing
Pasteurization Heating at
100°C
Heating above
100°C
Canning
https://solahart.com.au/media/5032/family-shot-
700-x-500.jpg
https://microbenotes.com/wp-
content/uploads/2019/02/Milk-Pasteurization-
Methods-Steps-Significance.jpg
https://arizonareport.com/wp-
content/uploads/2017/05/20170425_130600_
wm-e1494454980766.jpg
https://www.seriouseats.com/images/2012/02/201202
28-194981-mass-of-canning.jpg
Fig 4 Fig 6
Fig 5
Fig 3

17. a) Pasteurization
Heat treatment below 100°C by means of steam, hot water or dry heat &
electric current.
Used when
 More rigorous heat may destroy quality of food
 Aim is to only kill the pathogens
 Spoilage microbes are less heat resistant
 Preservatives also required
Some examples are:
1. Market milk heated at 62.8°C for 30 mins
2. Grape wine are pasteurized at 82-85°C for 1 min
3. Vinegar is pasteurized at 65.6-71.1°C for 20-30 mins
https://www.tekportal.net/wp-content/uploads/2018/12/pasteurization.png
Fig 7

18. Types of
pasteurization
High temperature
short time
(HTST)
Low temperature
long time
(LTLT)
161 F
for 15
seconds
145 F
for 45
minutes

19. ADVANTAGES
 Safe and reliable
Bulk non- pathogenic bacteria
are also killed
Increases shelf life of milk
DISADVANTAGES
 Can’t render dirty milk clean
 Reduces the cream line
 Chemical composition can be
altered
https://www.gea.com/en/binaries/Liquid-Processing-Equipment-
Compact-Milk-Pasteurizer-MWA-Milk-Cream_tcm11-23822.jpg
Fig 8

20. b) Heating at 100°C
c) Heating above 100°C
 Many acid foods such as sauerkraut acidic fruits are
processed at or below 100°C.
 Techniques like Baking, Simmering, Roasting, Frying,
etc. come under this criteria.
 Usually obtained by means of steam under
pressure sterilizers or Retorts.
 Temperature rises with increase of pressure.
https://www.tsa-inox.com/images/album_photo/diapo/100---copie0.jpg
Fig 9

21. d) Canning
• It is defined as preservation of food in sealed
containers implying heat treatment as principal
factor to prevent food spoilage.
• Tin cans/ Tin coated steel cans used.
• Nicolas Appert – Father of canning
• Tin canister was patented by Peter Durand
https://www.mealtime.org/wp-content/uploads/2020/08/canned-food-process.png
Fig 10

22. 2. Using Low Temperature

23. 2. Using low temperature
 Low temperature is used as it retards chemical reactions and action of
enzymes, also it can slow or stop microbial growth.
 Principle: As microbes have an optimum temperature of growth , reducing
that temperature may result in slow metabolism or prevent their growth.
 Two following types:-
a) Chilling or refrigeration
b) Freezing https://www.snipsmag.com/ext /resources/issues/2018/January/applications/Emerson-Industrial-Refrigeration.jpg?1514907525
Fig 11

24. Freezing
Foods are completely frozen and stored at -18°C
(Domestic freezers) and -29°C (commercial freezers)
Sharp or quick freezing are methods used for
different foods to ensure long term storage and
high quality.
Chilling/ Refrigeration
Encountered just above freezing point, normally at
5°C (domestic temp.)
Short term storage for milk, meat, eggs, fruits, etc.
May bring undesirable changes to food or its quality
https://www.chillzonerefrigeration.com/wp-content/uploads/2018/07/home_slide_commercial_2.jpg
Industrial freezer in Europe
https://www.frozenfoodeurope.com/wp-content/uploads/2015/12/web_100.jpg?x29101
Fig 12
Fig 13

25. 3.
Dehydration
or drying

26. 3. Using drying / dehydration
• Old method of preservation can be done by sunlight
• Principle: As microbes require water for growth and metabolism, reducing
water content below a crucial point, prevents growth of microbe.
Solar
drying
Other
methods
Accelerate
d Freeze
Drying
Mechanica
l drying
Freeze
drying
M
E
T
H
O
D
S

27. Solar
drying
https://www.iica.org.br/sites/default/files/ckeditor-images/secadoradomo-5_0.jpg
Mechanical
drying
https://previews.123rf.com/images/katoosha/katoosha1810/katoosha181000028/113822364-
process-of-mechanical-drying-of-sunflower-seeds.jpg
Freeze
drying
https://www.gea.com/en/binaries/Freeze-Dryers_RAY-plant1200x675__tcm11-16729.jpg
Tower
drying
https://www.solidswiki.com/images/c/c0/Tower_Dryers.jpg
Gun puffing
Fig 1
Fig 1
Fig 14
Fig 15
Fig 16
Fig 18
Fig 17

28. Disadvantages
Hygroscopic foods
easily absorb moisture
and food quality is
hampered.
Dried foods doesn’t
become pathogen free.
Drying can’t prevent
Gram negative spores
or mould spore
Advantages
Easy to reserve and
transfer
Low cost
Less space required

29. 4. By food
additives

30. https://forever4life.rs/wp-content/uploads/2019/02/E-1170x659.jpg
Principle: These inhibit
microbial growth by
interfering with their cell
membranes or enzymatic
activity or other genetic
mechanisms.
 Food additive is a substance / mixture of substances other than basic
food stuff i.e. present in food to enhance its production, storage,
processing or packaging.
 And those added to prevent spoilage are called preservatives.
Fig 19

31. https://pesproppt.files.wordpress.com/2015/03/lec17-page-001.jpg

32. Categories of
food
preservatives
Benzoates
Sulfates
Ethylene &
propylene
oxide
Ethanol and
other
alcohols
Wood
smoke
Sorbates
Acetates
Nitrates &
Nitrites
Others like
Halogens,
hypo
chlorites
Propionates

33. • Nisin is a principal antibiotic permitted as
food preservative in cheese, clotted cream,
canned foods. Used to increase shelf life of
food items.
• Thiabendazole highly accepted after nisin.
Antibiotics

34. 5. By high osmotic
pressure.

35. > Common salt (NaCl) is one of the oldest
preservation methods used by man due
to osmotic pressure.
> PRINCIPLE: Under osmotic conditions,
water is removed from the microbial cell &
cell gets plasmolyzed , metabolism is
arrested then cells die.
> Salt conc. 25% practically inhibits all
microbes except halophiles.
> Cane sugar is also used in 60-70% conc.
Usually in jellies and jam

36. 6. By Radiation

37.  Irradiation is a novel technique when the other preservation
techniques are insufficient.
 PRINCIPLE: The entire spectrum is divided into low & high frequency
region ranging from UV to cosmic rays. The high frequency region
can destroy microbial cells due to its high energy.
 It includes
- Non-ionizing radiations( UV rays)
- Ionizing radiations
 Microwave Processing
Very popular at consumer level and it’s a technique to heat, cook food
also killing the microbes.

38. Irradiation
https://www.iaea.org/sites/default/files/styles/original_image_size/public/d61025photo.jpg?itok=AejWagsO
Fig 20

39. 7. Other Preservation Techniques
MAP(modified atmosphere packaging)
It is the enclosure of food items in gas barrier materials in which gaseous environment can be maintained.
Pulsed Electric fields(PEF)
It involves application of short electric pulses of high field strength to food samples placed between two electrodes causing
electroporation.
https://www.generon.com/wp-content/uploads/2018/11/how-does-modified-atmosphere-packaging-work.jpg

40. http://i3food.eu/wp-
content/uploads/ELEA_PEF_machine.jpg
http://i3food.eu/wp-content/uploads/PEF1.jpg
https://img.favpng.com/13/7/16/packaging-and-labeling-meat-packing-
industry-food-png-favpng-dSdBHmT9NGzSfdKXFQ5x1YGmx.jpg
https://genuineideas.com/Assets/imageassets/UZXtendaPak_CrossSection_RedMeat.png
PEF process illustration scheme
PEF installation at ELEA (Germany)
Fig 24
Fig 23
Fig 22
Fig 21

41. Applications

42. Waystopreserve
Cereals and grains
Use of heat
Use of Low temperatures
Use of chemical preservatives
Using irradiation

43.  Use of heat
 Use of low
temperature
 Drying
 Added preservatives

44. Waystopreserve
Meat & chicken
 Use of he a t
 Use of L ow
te mp e r a tur e s
 De hy d r ation
 Use of p r e se r va tive s
 Using ir r a d ia tion
https://i.pinimg.com/564x/97/73/37/977337427090c1f94714d6740a05281d.jpg

45. https://fiverr-
res.cloudinary.com/images/t_main1,q_auto,f_auto,q_auto,f_auto/gigs/114083772/original/e14c589
fa855fe1527d3d7138c696487c0f44ab1/shape-your-mind-with-milk-and-its-products.jpg
Ways to preserve
Milk and its
products
o Use of heat
o Low temperature
o Drying
o Use Preservatives
Fig 25

46. New trends and techniques in Food preservation
https://foodsafetytech.com/wp-content/uploads/2018/09/Worker-loading-HPP-meats.jpeg
https://cdn-a.william-reed.com/var/wrbm_gb_food_pharma/storage/images/3/4/8/1/3141843-1-eng-GB/Hiperbaric-
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H
H
P
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U
L
T
R
A
S
O
U
N
D
V
A
C
U
U
M
https://www.nationalproductreview.com/wp-content/uploads/2018/02/KDK911423M_Insitu.jpg
Fig 26 Fig 27
Fig 28 Fig 29

47. References
• Frazier W C, Westhoff D C. “Food
Microbiology(1998) , McGraw-Hill Inc., Fourth
Edition, 81-309
• Zeuthen P, Sorenson L B. Food Preservation
techniques(2003) Woodland publishing limited,
First edition, 71-401
• Patel A H. Industrial microbiology(2011) Lakshmi
Publications, Second edition, 218 – 235
• https://www.britannica.com/technology/meat-
processing/Preservation-and-storage
• http://i3food.eu/pulsed-electric-field-
preservation/