Presentation about Meat preservation .pdf

Presentation about meat preservation

1. Meat preservation

2. Purpose of food preservation
1)retard spoilage.
2)Prevent changes in flavor, texture, odor and appearance.
3)Prevent changes in nutritive value.
Food spoilage
Occur by the action of microorganisms(bacteria, yeast, molds)
Due to autolytic changes including enzymatic actions
chemical actions
physical actions
Keeping the food safe and edible for consumers

3. Main principle of food preservation methods
➢Create unfavorable conditions to the growth or survival of spoilage organisms.
➢Destruction of such spoilage organisms.
unfavorable conditions to the growth of microorganisms
1)Extreme heat
2)Extrema cold
3)Deprivation of water
4)Deprivation of oxygen
5)Excess of saltiness
6)Increase acidity
Meat is nearly neutral
pH, high moisture, rich
in nutrients

4. Classification of preservation methods
A.Methods for prevention of microbial decomposition
(bactericidalmethods) Canning, Irradiation
B. Methods for hindering the growth and activity of microorganisms.
(bacteriostaticmethods) Chilling
Freezing
Smoking
Drying
Curing, salting
Methods depend on prevention or delay self
decomposition of food by destruction or
inactivation of autolytic enzymes (blanching)
or delay chemical relation (add antioxidant)

5. Growth curve of microbial cultures

6. Thelag phaseis an adaptation period, where the bacteria are adjusting to their
new conditions during which there is no growth of microorganisms (no
multiplications)
Theexponential or log phaseof growth is marked by predictable doublings of
the population, where 1 cell become 2 cells, becomes 4, becomes 8 etc. Conditions
that are optimal for the cells will result in very rapid growth ( rapid multiplication)
The stationary or constant phase during which the number of bacteria remain
constant.
Decline or death phase during which the number of microorganisms decrease.
Importance of lag phase for meat preservation:
lengthen as much as possible is special importance
in food preservation

7. Preservation of meat by using high temperature
1)Canning
is a method of preservation of food in which the food contents is processed and
sealed in airtight containers ( metal, glass or thermostable plastic)
Canning depend on heat process
A septic canning is a new method which depend on use of high temp. for short
periodas the food is sterilized at 120
o
C for 5 to 6 min. depend on type of food then
packed in a sterilized can and closed with a sterilized lid.
In modern canning operation there must be sufficient heat to reduce population
of Cl. botulinumspores.
Canning process divided into 2 categories according to heat process
a)Thermal sterilization or commercial sterilization (at 120
o
C for 5 to 6 min)
b)Pasteurization ( heated enough to kill part of spoilage M.Os.)

8. Foods that are canned
1)low acid food: meat, fish, poultry and dairy fall into a pH ranged from 5.0-6.8
2)Acid food: Fruits ( orange, apple pear& tomatoes) pH ranged from 3.5-4.5
3)High acid food : pickled and fermented products as grapes, lemon, berries and
pineapples pH ranged from 2.5-3.5

9. Canning operation
1)Filling 1) automatic machine
2) Manual filling
Should be fill correct weight to avoid problems during filling step
over filled cans Under filling
delay time between filling and processing step
under processing,
distortion of can’s
seam
air pockets
allow m.os. To grow with loss of quality

11. 2) Exhausting: remove air from can before sealing
Exhausting of cans is necessary to prevent expansion of the content during
processing to
Produce concave can ends
so could be detect any
internal pressure
Flipper, springer, blower
Lower of oxygen in the
cans
Prevent discoloration
of food surface
Reduce chemical
reaction between food
and container
prevent hydrogen
swell

12. Exhausting occur by to methods
1)Heat or thermal steam Exhausting.
The can is passed through a steam-heated chamber before sealing the ends are loosely
attached to permit escape of air and it well be sealed after exhaustion.
2) Mechanical vacuum Exhausting.
The can is filled with cooled food,
is closed in vacuum-closing machine.
The can is exposed to high vacuum during sealing.

13. 3)Processing: septic canning using tm
o
120
o
C/ 5-6 min.
It is heating not sterilization this mean organisms may still alive, the temp.depends on
type of food andtype and number of bacteria which may be present.
processed by steam pressure.
During processing heat penetrates the center of cans by
1)Conductionas in solid meat (slow process)
2)Convection as in loosely packed food or liquid (fast process)
to kill yeast, mold and bacteria. for the destruction of bacterial spores
For acid food (pH below 4.5as fruits)
need temp. at 93
o
C
In non acid food (pH above 4.5)
such as meat need 115
o
C

14. Give chance for bacterial
spoilage.
Under processing:
Make alteration in color,
texture and flavor
Over heating:

15. 4) Cooling: Cans are cooled to 38
o
C.
Cooling after processing is necessary
❖for prevention of the action of over heating
❖reduces the internal pressure of cans which has been formed during processing.
It is done by one way of these:
1. Cans placed under cold water showers.
2.Immersed in a cold water tank.
3.Pressure cooled in water spray retort.
The water used:
✓standard acceptable for public drinking water(free residual chlorine 0.5 ppm or more)
✓River water should be filtrated as chlorine has little effect in presence of organic
matter
✓no coliform in water.

16. 5) Can washing:
To remove dirtand greasefrom outside the can they washed in a bath with soap
or fatty alcohols as lauryl, stearyl, and oleyl alcohols.
Then rinsed with water.
6)Outside lacquering:
is a resin coating of cans which protect the can, preventing metal corrosion
specially in high humidity.
Lacquer or enamel is a color varnish containing vegetable or synthetic resin.
It is applied to outside the tin to prevent external corrosion and protect tin from
chemical reaction with out affect food color also prevent dissolution of tin into
products
➢Phenolic lacquer
➢Epoxy lacquer

17. Spoilage of canned food
Keeping quality of canned foods depend on:
1-Complete exclusion of air
2-Thermal processing
3-Sealing of cans
❑Spoiled cans show obvious abnormalities
❑Normal shape of cans: two ends are concave
Distortion
Blowing
Convex
ends
Slightly
constricted
side

18. ❑Spoiled cans show
1. A flipper:
A can of normal appearance in which one end flips out. When the can is
struck against a solid object, but the end snaps back to the normal when very light
pressure is applied.
2.A springer:
A can in which one end is bulged but can be forced back into normal
position, whereupon the opposite end bulges.
All blown cans pass successively through the flipper and springier stages,
which must be regarded as suspicious of early spoilage of the contents.
3.Swell or blower:
A can with its end bulged by positive internal pressure due to gas generated
by microbial or chemical activity, it emits a resonant sound.

20. A-Microbial spoilage
Microbial spoilage of cans occur due to:
1-under processing.
2-leakage of cans.
Aerobic spore forming bacteria may be
present in sound cans remain dormant
under anaerobic condition but if supplied
air through faulty sealing it will be produce
decomposition of can’s content.

21. ➢Flat souring
Susceptible foods
✓Foods contain sugar or starch
✓Meat products as sausagecontain cereals
Causative microorganisms
Thermophilic organisms
B. Coagulans
B. Stearothermophilus
B. Circulans heat resistance
Characterized by
attack carbohydrates with production of acid only

22. ➢Sulfide spoilage
❑Susceptible foods
✓Low acid foods as meat-fish-peas -corn
❑Causative microorganisms
Cl. Nigrificanceproduce H2S detected by odor of cans
detected on iron sulfite agar at 55C give black colonies
❑Characterized by
✓Spore forming
✓Less heat resistance so its present in canned food indicate under processing

23. ➢Thermophilic anaerobic spoilage
❑Susceptible foods
✓Low and medium acid foods
❑Causative microorganisms
Cl. Thermosaccharolyticum produce H2, CO2 no H2S
detected by sour odor and swell of cans
❑Characterized by
✓Spore forming
✓Sugar splitting
✓Obligatory thermophilic M.O.
✓Form acid and gas

24. ➢Spoilage by non spore forming bacteria
❑Occur due to
✓Under processing ( mild heat treatment)
✓leakage of cans after processing
❑Causative microorganisms
Enterococci, Lactobacilli produce CO2
Streptococcus thermophilus
cause swell of cans
❑Non gas forming bacteria
✓proteus
✓Achromobacter
✓Flavobacterium

25. A-Chemical spoilage
Chemical spoilage of cans includes:
1.Hydrogen swell
2.Sulphiding
3.Rust or damage

26. Hydrogen swell
Chemical spoilage of cans
Associated with formation of hydrogen gas in the cans following
❖Internal corrosive imperfection
❖Scratches on the inner tin coating
So exposed of steel
➢If food contents are acid pH3.5-4.5 as fruits
➢or present of sulfurand phosphoruscompounds as canned fish
➢Long timeof storage
➢Poor exhaust
Favorable condition of hydrogen swell

27. Sullphiding
Chemical spoilage of cans
➢Occur in canned food rich in sulfur content meat products, liver, kidney and tongue
➢High processing tm. lead to break down sulfur contain protein
lead to liberation of H2S
H2S will combined with inner coating of tin
H2S + tin tinsulphid
H2S will combined with inner coating of tin
H2S + steel iron sulphid
steel biting
Not involved food (inner wall only of cans)
light pink color to purple
Not harmful to human
➢Causing discoloration of food surface
➢Black color of inner wall and surface of
content
➢Harmful to human

28. Sulphidingavoided by
➢Using phenolic lacquer
➢Sulfur resistance lacquer
Rust or damage
➢External surface with slight rust and no biting of iron may be consumed
➢If steel biting should be condemned
➢Rust may be lead to minute perforation of tin layer(pin holding)
➢Permit entrance of air lead to spoilage of cans content