Meat microbiology is the study of the microorganisms that inhabit, create, or contaminate meat, including the study of microorganisms causing meat spoilage. We should Understand the basic microbiological activities, there growth regulator and control their affects in Meat products.

1. Basic Meat Microbiology
Sabbir Ahmed

2. Objectives
Understand the basic microbiological
activities, there growth regulator and control
their affects in Meat products

3. At A Glance
1. Introduction,
2. Naming of microbes
3. Food Toxicity
4. Identification of Microorganism
1. Gram positive and gram negative bacteria
2. Temperature tolerance
3. Oxygen tolerance
4. pH tolerance
5. Aw tolerance
5. Major microbes for meat spoilage

4. Introduction
Baddy 2% vs Buddy 98 %
Y = Young(Children)
O = Old
P = Pregnant
IS = Immunocompromised segment
Food microbiology is the study of the microorganisms that inhabit,
create, or contaminate food, including the study of microorganisms
causing food spoilage.

5. Naming of Microbes
• Genus name first letter upper case
• Species name all letter lower case
• Italic while typing
• Italic and underlined while hand writing
Full Name Sort Name
Escherichia coli E. coli
Staphylococcus aureus S. aureus
Bacillus cereus B. cereus
Clostridium botulinum Cl. Botulinum
Clostridium perfringens Cl. perfringens
Listeria monocytogenes L. monocytogenes
Salmonella typhi S. typhi
এসেসেশিয়া কশি
স্টেফাইিককাছ অশেয়াে
স্টেশছিাছ শছোছ
ক্লশিশিয়াম েটু িাইনাম
ক্লশিশিয়াম পােশিসেন্স
শিেসটশেয়া মনওছাইটসেসনছ
স্টছল্মসনিা টাইশপ

6. Food Toxicity
Food Toxicity
Food Infection
Endotoxins
Food Intoxication
Exotoxins
Cytotoxin, Enterotoxin,
Neurotoxin.
Exotoxin
• Produced through metabolic activities inside bacteria
• Exotoxins Are Soluble In Body Fluids
• Present Inside The Consumed Food
• Incubation time: 03-04 hours
• Proteins Synthesized toxin
• Gram Positive Bacteria
Endotoxin
• Gram Negative Bacteria
• Incubation time: 08-16 hours
• Toxin Produced By Lipid Fraction (Lipid A)
• Multiplication of Bacteria Within The Gastrointestinal System

7. How Endotoxin Produce
Lipopolysaccharide(LPS) represents the actual toxin.
Present in outer cell membrane
Release through lysis of cell
Increase number

8. Food Toxicity
Bacteria causing food-based infection or intoxication
Food Infection Food Intoxication
Campylobacter jejuni Bacillus cereus
Escherichia coli Clostridium botulinum
Listeria monocytogenes Staphylococcus aureus
Salmonella typhimurium
Yersinia enterocolitica
Shigella spp

9. Gram-positive & Gram-negative Bacteria
Identified by Gram Stain Test
(Physical properties of cell walls)
• Gram-negative bacteria are more resistant to antibodies because of
their impenetrable cell walls.
• 90-95% of Gram-negative bacteria are pathogenic

10. Gram-positive & Gram-negative Bacteria
Danish microbiologist
Hans Christian Gram
(1853–1938)
• Firstly, bacteria are colored with the aniline dye crystal violet.
• Secondly, washed with 95% concentrated ethanol
• Due to the presence of a thick layer of peptidoglycan in their cell
walls, Gram-positive bacteria retain the crystal blue– violet color
• Gram-negative bacteria are completely decolorized
Identified by Gram Stain Test
(Physical properties of cell walls)
• The counter-stain safranin, or fuchsin, is applied afterwards
• That will stain these gram-negative bacteria a pink color.
• The counterstain, however, is unseen on gram-positive bacteria
because of the darker crystal violet stain.
It is important to recognize that this class is defined morphologically (by the presence of a bacterial outer membrane)

11. Major Gram bacteria in meat
Gram-positive genera Gram-negative genera
Bacillus Pseudomonas
Clostridium Escherichia
Staphylococcus Salmonella
Streptococcus Enterobacter
Lactobacillus Campylobacter
Listeria
Gram-negative bacteria only 100 can cause serious illness

12. Temperature tolerance
Classified into five group

13. Temperature tolerance
Growth temperatures for spoilage bacteria and pathogens
Minimum (°C) Optimum(°C) Maximum(°C)
Campylobacter jejuni 30 40 45
Clostridium perfringens 17 40 50
Escherichia coli, 7 37 45
Staphylococcus aureus 7 37 45
Salmonella 5 37 45
Clostridium botulinum 3.5 38 50
Lactobacillus, 0
Listeria monocytogenes 0

14. Oxygen tolerance
Oxygen
Tolerance
Aerobic
Obligate Microaerophile
Anaerobic
Obligate Facultative
Can use O2 if present
Can live without oxygen
CO2 stimulate growth
(E. coli, Salmonella spp.
Staph. aureus, L. monocytogenes)
O2 acts as a poison
(Cl. Botulinum)
Require oxygen to live and to grow
Poisoned by high concentrations of O2 (> 6%)
CO2 (10–12)% stimulated Growth

15. pH: Growth of Bacteria
• Living muscle approximately pH = 7.2.
• Post slaughtering pH 5.3-6.5 because of the conversion of glycogen into lactic acid
But pH values rise after rigor mortis owing to the metabolic activity of protease.

16. Microorganism pH
Clostridium botulinum > 4.6
Clostridium perfringens > 4.9
Lactobacillus spp. > 3.2
Salmonella spp. > 4.4
Staphylococcus aureus > 4.6
Listeria monocytogenes > 5.0
Escherichia coli O157:H7 > 4.0
pH - Growth of Bacteria

17. Water Activities
P is the vapor pressure of food at a certain temperature
P0 is the vapor pressure of pure water at the same temperature
Aw is the relative humidity (RH) of food divided by 100
(e.g. 98.5/100 results in Aw = 0.985).
The amount of free unbound water within the product in
relation to its total water All water is unbound and available
for bacteria as a source of food.
Aw = 0.00 -1.00

18. Water Activities
Genus or species Minimum Aw
Campylobacter jejuni, 0.97
Clostridium perfringens 0.97
Enterobacteriaceae (Salmonella ssp. and
Escherichia coli),Clostridium botulinum
0.95
Lactobacillus spp. 0.93
Listeria monocytogenes 0.92
Staphylococcus aureus 0.90
Most species of yeast 0.88
Most species of mould 0.80

19. Major Microbes for meat spoilage
• Salmonella.
• Escherichia coli
• Campylobacter jejuni
• Clostridium
• Listeria monocytogenes
• Staphylococus aureus
The main microbiological hazards associated
with raw poultry meat are contamination
with
• Salmonella
• Campylobacter

20. Genus Salmonella
• Gram-negative, rod shaped,
• Non-spore forming,
• Facultative anaerobic;
• Endotoxins producing bacteria
• Incubation time: 10–16 h
Growth Regulator
• Growth temperatures: 5 - 45°C.
• Destroyed by a temperature of 72 °C
• Aw above 0.95 pH above 5.5 in order to produce toxins,
• Aw at or above 0.92 and a pH above 4.4 for growth.
Family Enterobacteriaceae
• S. typhi
• S. typhimurium
• S. enteritidis
Daniel Elmer Salmon
(1850 – 1914)

21. Genus Salmonella - Sources
Cross contamination
Contaminated
raw materials
Inadequate
processing of
raw products

22. Genus Salmonella
Symptoms:
• Causing vomiting
• Abdominal cramps
• Septicemia
• Headache and diarrhoea

23. Control
Genus Salmonella
Satisfactory Level: Not detected in 25g

24. Genus Salmonella- Risk Assessment
Investigation and corrective actions:
• Breeder farms
• Hatcheries
• Feed production
• Transport
• Broiler farms
• Live haul equipment and transport
• Processing plant equipment
cleaning and maintenance

25. Genus Salmonella- Potentially hazards
Investigation and corrective actions for Potentially hazardous:
• Raw material fitness
• The adequacy of processing used (e.g. adequate cooking, pH, water activity)
• The adequacy of measures implemented to prevent the likelihood of cross
contamination
• The effectiveness of cleaning and sanitizing equipment
• The adequacy of time and temperature controls used.
• The adequacy of health and hygiene practices
• Confirmation of identity, where cases of foodborne illness suspected.

26. GenusEscherichia
Theador Escherich
(1857-19911)
Indicators of the level of hygiene in a factory
Family Enterobacteriaceae
• E. coli. is Gram negative
• Facultative anaerobic
• Incubation: 1-10 days
• Enterotoxins destroyed over 100 °C for 35 mins
Growth Regulator
• Temperature range: 7-45 °C
• pH value for growth is 4.5-8.8
• Aw ≤ 0.95 to inhibit growth
Escherichia coli O157:H7

27. Genus Escherichia
Sources
• Undercooked ground beef, unpasteurized (raw) milk and juice,
• Soft cheeses made from raw milk,
• Raw fruits and vegetables
• Untreated water and swimming water
• Animals and their environment
Symptoms
• Bloody diarrhoea
• Abdominal cramps
• Vomiting
• Hemolytic uremic syndrome (HUS)

28. • Cleaning and sanitizing practices for premises and equipment
• Food handler hygiene
• Keep food ≤ 4°C
• Cook to temperature more than 72°C
• Primary production controls
• Keep kitchens and food-serving areas clean and sanitized
Control
Genus Escherichia
Corrective actions to be taken include review of process controls, including:
• For birds prior to entering the slaughter facility
• Following evisceration and prior to birds entering the washing process
• For the carcass decontamination process
• For chilling of poultry meat carcasses

29. Genus Campylobacter
Family Campylobacter
• Gram negative
• Thermophilic
• Facultative anaerobic / microaerophilic
• Incubation: 2-5 days
Growth Regulator
• Temperature range: 30-45 °C
• pH value for growth is 6.5–7.5.
• Aw 0.97 is required to growth
• Growth inhibited below pH of 4.9 and above pH 9.0
Curved bacteria• Campylobacter jejuni
• Campylobacter coli
• Campylobacter fetus

30. Genus Campylobacter
Sources
• Inadequate processing of raw products
• Undercooked meat
• Cross contamination of raw materials
• Raw meat, Unpasteurized milk
• Non chlorinated water/ contaminated ice, inadequately treated water
• Animals and their environment: particularly poultry
Symptoms
• Serious diarrhea with fever
• Abdominal cramps

31. Genus Campylobacter
An investigation should be undertaken to assess:
• The adequacy of processing used (e.g. Adequate cooking; pasteurization)
• The adequacy of measures implemented to prevent the likelihood of cross contamination
• The possibility of untreated water being used.
• Keep food ≤ 4°C
• Core temperature more than 80°C
• Control raw material
• Control water treatment plant
Control
Satisfactory Level: Not detected in 25g

32. Genus Clostridium
• Clostridium perfringens
• Clostridium botulinum
Family Bacillaceae
• Gram positive
• Non- proteolytic
• Obligate anaerobic
• Incubation: 8-14 hours
• Create H2S- off flavor
Growth Regulator
• Temperature range: 20-45 °C
• pH value for growth is 4.9-8.3
• Aw more than 0.95 required to growth
Botulinum comes from Latin word
“botulus” meaning sausage

33. Genus Clostridium
Sources
Symptoms
• Soil
• vegetable dishes
• Meat, Particularly rolled and large joints
• Abdominal pain, fever , vomiting
• Blurred speech, double vision, Paralysis of respiration,
1.0 micro gram of exotoxin can causes death

34. Genus Clostridium
• Packaging- Absent of oxygen and presence of nitrite
• Cool quickly after cooking ≤ 4°C
• Cook to temperature more than 121°C for 4 mins or 111°C for 30 mins
• Keep kitchens and food-serving areas clean and sanitized
• Wash properly before processing
Control
CFU/g <10 Satisfactory

35. Genus Listeria
Family Listeriaceae
L. monocytogenes
• Gram-positive, Non-spore-forming,
• Facultative anaerobic
• Rod-shaped bacterium
• Incubation time: 3-70 days
Growth Regulator
• Temperature range: 0-38 °C
• pH value for growth is 5.0-5.9
• Aw ≤ 0.92 and pH < 4.1 inhibit growth
• Temperature below –2°C inhibits growth

36. • Unpasteurized (raw) milk and dairy products
• Soft cheese made with unpasteurized milk
• Carried by many domestic and wild animals.
• Raw inadequately processed meat
• Harbor these bacteria include drains, floors, conveyors, chilled storage areas, and in
cracks and crevices of equipment
Symptom
• Fever, stiff neck, weakness, vomiting,
• Sometimes preceded by diarrhea
Sources
Genus Listeria

37. • Appropriate cleaning and sanitizing of premises and equipment before/after handling
and preparing uncooked foods.
• Rinse raw produce thoroughly under running tap water before eating.
• Keep cooked and uncooked meats separate
• Store the product below –2°C
• Internal temperature.( >72°C)I
• Bacteriocins- sacacin inhibit the growth
• Using listericidal processes
• Control Good Hygiene Practices (GHP)
Genus Listeria
Control
GHP

38. Genus Staphylococcus
Family: Micrococcaceae
• Gram-positive
• Facultative Anaerobic
• Spherical bacterium
• Produces enterotoxins.
• Incubation time is 2–6 h
Growth Regulator
• Temperature range: 7-45 °C
• pH value for growth is 7.2–7.6,
• Production of toxins stops at pH ≤5.2 or an Aw ≤ 0.90.
• S. aureus – humans
• S. arlattae – chickens, goats
• S. cohnii – chickens, humans
• S. leei – humans
• S. xylosus – humans

39. Genus Staphylococcus
Symptoms
• Nausea, vomiting, diarrhea, loss of appetite
• Severe abdominal cramps, mild fever.
Source
• Food handlers are regarded as the main source of food contamination with S
• Respiratory secretions
• Foods that are made with hand contact and require no additional cooking
(e.g. Salads, egg, potato, Bakery products, Sandwiches)
• Milk and dairy products,
• Meat, poultry, eggs, and related products.
• Human skin

40. • Hygiene of food handlers, Control GMP
• Keep hot foods ≥60°C and cold foods cold ≤4°C
• Avoid preparation of food with nose or eye infection, wounds or skin infections
• Preventing unnecessary contact with food
• Using gloves, tongs or other implements to handle food
• Avoiding sneezing, coughing or blowing over food or food contact surfaces.
• Avoid eating perishable food prepared more than two hours earlier
Genus Staphylococcus - Control

41. Resources for Further Study
• Codex (2007) Guidelines on the Application of General Principles of Food Hygiene to the Control of Listeria
monocytogenes in Foods CAC/GL 61-2007
• Food Standards Australia New Zealand 2018: Compendium of Microbiological Criteria for Food, September
2018, ISBN: 978-0-642-34594-3
• Regulation on Turkish food codex microbiological criteria, 29.12.2011-28157
• The International Food Safety Authorities Network (INFOSAN)
• Baylis C, Uyttendaele M, Joosten H, & Davies A (2011) The Enterobacteriaceae and their significance to the
food industry. International Life Sciences Institute (ILSI), Europe.
• Meat products handbook, Practical science and technology- Gerhard Feiner Baylis C, Uyttendaele M, Joosten H,
& Davies A (2011)
• The Enterobacteriaceae and their significance to the food industry. International Life Sciences Institute (ILSI),
Europe.
• FDA (2012) Bad bug book: Foodborne pathogenic microorganisms and natural toxins handbook, 2nd ed, US
Food and Drug Administration, Silver Spring, p. 75–79.

42. Thank You