2. MICROBIAL SPOILAGE OF
MEAT AND POULTRY
PRODUCTS
Presented by:- Ketaki Patil
SRM university, Chennai

3. What is Spoilage???
• Spoilage is the process in which food
deteriorates to the point in which it is not
edible to humans or its quality of edibility
becomes reduced.

4. What is microbial
spoilage???
• Microbes can be responsible for the
spoilage of food. When they breaks down
the food, acids and other waste products
are created in the process. While the
microbes itself may or may not be harmful,
the waste products may be unpleasant to
taste or may even be harmful to one's
health

5. How it occurs???
• Normal slaughtering techniques
• External sources during bleeding,
handling, skinning, cutting and processing.
• Intestinal tract of animals, exterior of
animals ( hide, hooves and hairs)
• Knives, cloths, air, and hands and
clothing of workers.
• Depends on methods of slaughtering
methods such as mechanical,
chemical, electrical etc.

6. MEAT SPOILAGE
• Raw meat is subject to change by its own
enzymes and microbial action and its fat
may be oxidized chemically.
• Autolysis changes include some
proteolytic action on muscle and
connective tissue and slight hydrolysis of
fats.
• The defect caused by excessive autolysis
has been called “souring”

7. Invasion of tissue by micro
organism
• Upon the death of the animal, invasion of tissue
by contaminating micro organism takes place.
• Factors influence that invasion includes
following:-
• The load in the gut of the animal
• The physical condition of the animal immediately
before slaughter
• The method of killing and bleeding
• The rate of cooling

8. Growth of micro organism in
Meat
• Meat is an ideal culture for many microbes
because it is high in moisture, rich in
nitrogenous foods of various degree of
complexity , and plentifully supplied with
minerals and accessory growth factors.
• Also, it usually has some fermentable
carbohydrate( glycogen) & is at favorable
pH for most micro-organism.

9. Factors influence growth of
microorganism
• The kind & amount of contamination with
microorganism and the spread of these
microorganism in the meat.
• The physical properties of the meat
• Chemical properties of the meat
• Availability of oxygen
• Temperature

10. Types of Spoilage of Meats
• Spoilage under
1)Aerobic conditions
2)anaerobic conditions

11. Spoilage under Aerobic
conditions
• Under aerobic conditions bacteria may cause
the following-
• Surface slime – which may be caused by
species of Pseudomonas, Acinetobacter,
Moraxella, Alcaligenes, streptococcus,
Leuconostoc, Bacillus, and Micrococcus
• It is early indication of spoilage, often observed
before expiry date.

12. • Changes in color of meat pigment- The red color
of meat, called “bloom”, may be changed to
shades of green, brown, gray as result of the
production of oxidizing compound . e.g.
hydrogen peroxides, hydrogen sulfide.
• Lactobacillus and Leuconostoc are basically
responsible.
• Changes in fats:- The oxidation of unsaturated
fats may takes place chemically in air and may
be catalyzed by light and copper. e.g. oxidative
rancidity
• Pseudomonas and Achromobacter are
responsible for oxidative rancidity or by yeast.

13. • Phosphorescence – This rather uncommon
defect caused by phosphorescent or luminous
bacteria. E.g. Photobacterium spp. Grows on the
surface of meat.
• Various surface colours due to pigmented
bacteria:- red spot may be caused by Serratia
marcescens or other bacteria with red pigment.
Pseudomonas syncyanea can impart blue color
to the surface, Micrococcus or flavobacterium
imparts yellow color with yellow pigment and
Chromobacterium lividum and other bacteria
gives greenish blue or brownish black spot.

14. • Off odors and off taste:- “Taints” or undesirable
odors and tastes, that appear in a meat . “
souring” is the term applied to almost any defect
that gives the sour odor that may be due to
volatile acids. e.g. formic, butyric,propionic acids
• “Cold storage flavor” or taint its nothing but stale
flavor.
• Actinomycetes may be responsible for Musty or
earthy flavor

15. Aerobic growth of moulds
may causes
• Stickiness – surface becomes sticky
• Whiskers- when meat is stored at temperatures
near freezing, a limited amount of mycelial
growth may takes place without sporulation.
• Black spot- this usually caused by Cladosporium
herbarum
• White spot- Sporotricum carnis mostly causes
white spots.

16. • Green patches- this occurs due to species
Penicillum such as p.expansum
P.oxalicum
• Decomposition of fats- many molds have
lipase and hence cause hydrolysis of fats .

17. Spoilage under anaerobic
conditions
• Facultative and anaerobic bacteria can
able to grow within the meat under
anaerobic conditions and cause spoilage.
• Following changes occurs in such
conditions
• Souring
• Putrefacation
• Taint

18. • Souring – it imparts sour taste to meat due to
acids such as formic, propionic, acetic etc.
meat’s own enzymes are responsible for it .
• Putrefaction- true putrefaction is the anaerobic
decomposition of protein with the production of
foul smelling compound such as hydrogen
sulfide, indole, ammonia, amines due to species
Clostridium
• Taint - Taints” or undesirable odors and tastes,
that appear in a meat

19. Various spoilage features of
Meat
• Off odor-off flavours
• Discoloration
• Gas production

20. Off –odors & off flavours
• Off odors such as sweet and fruity, putrid,
sulphury and cheesy, are characterized in
aerobically stored meat.
• Species which are responsible
Psuedomonas sp. & Psuedomonas fragi
• Sulphur compounds may also contribute
off flavor

21. Discoloration
• The bacterial production of hydrogen
sulphide converts the muscle pigment to
green sulphmyoglobin.
• Hydrogen sulphide is produced from
cystein and is triggered by glucose
limitation L.sake forms hydrogen sulphide.

22. Gas production
• Clostridium spp. have been associated
with the production of large amount of gas
in vacuum packaged beef , accompanied
by foul off-odors. Gas production (co2) by
lactic acid bacteria without extensive off
odors may be associated with vacuum
packaged beef and pork.

23. organism Responsible for changes
Psuedomonas species Off odor and off flavor
Microbacterium thermosphactum Spoilage in processed meat
Achromobacter species Spoilage in processed meat
Lactobacter species Spoilage of vacuum packaged cuts or
ground meat
Moulds species like Cladosporium Spoilage of beef sides or quarters
during prolong storage at 0°c.

24. Cured meat type Spoilage organism
Sliced ham and bacon Souring due to Streptococcus faecium,
& Microbacterium thermosphactum
Pasteurized canned product Bacillus sps., clostridium
sps.,enterococci, streptococci and
heat resistance lactic acid bacteria
Refrigerated canned product Streptococcus sps.

25. Type of sausage Type of spoilage Organism responsible
Fresh uncooked sausage Putrefaction souring Achromobacter and
Psuedomonas &
Microbacterium
thermosphactum,
Cooked sausages Irregular green spots on
surface, green cores
Narrow green rings
within the product
Lactobacteriaceae,
Leuconostoc,
streptococci and
pediococci
Cooked sausages sliming Yeast , Microbacterium
thermosphactum

26. References
• Willam C. Frazier Food microbiology
• Principles Of Meat Technology by V.P
Singh
• Food microbiology by K. Vijaya Ramesh