L. Assistant Rawa abdul Redha Aziz
FOOD MICROBIOLOGY LAB 5
Microbiological Spoilage of Meat and Poultry
**Meat is considered as an excellent medium for microorganisms
since it cantains nitrogens, carbohyderates, minerals , and salt. Also, it
contains high water activity and low pH (~ 5).
**Normal microflora of meat are (Pseudomonas ,
Lactobacillus , Bacillus , Leuconostoc , Micrococcus).
**It is not be necessary that polluted meat change in color
and odder.
**Meat might has dangerous contaminants such as
Clostridium.
**The spoilage of meat is normally referred to metabolism of M.O.
**The bacterial content in polluted meat is 50-100×106 cell/
cm2 (gram)
Source of meat and poultry contamination
1-Soil, water, air and cutting equipments
2- food handlers
3- Transporting and Marketing
Types of meat spoilage:
1- Odor & slime
The first indicator of meat spoilage is off-odder and slime that mainly
caused by Pseudomonas.
2- Discoloration
Because of the microbial metabolism in meat, the color will be
changed as followed:
Collage of Science/ Kufa University
Fourth Level
L. Assistant Rawa abdul Redha Aziz
Pseudomonas
Serratia
FOOD MICROBIOLOGY LAB 5
Green spots
Red spots
Bacteria
Rhodotorula
Red-pinkish
Yeast
Cladosporium
Sporotrichum
Penicillium
Black spots
White spots
Green spots
Molds
3-Putrefaction & Rancidity
Putrefaction is caused by Proteolytic bacteria (e.g. Pseudomonas) under
anaerobicaly conditions.
H2S +NH3
Protein
Protease
Meat Fat
Fatty acids+ Glycerol
4-Meat Souring
When meat is stored under room temperature, Mesophiles bacteria (e.g.
Coliform and Lactobacillus) oxidize sugar to organic acids.
5- Gas production
The important gas produced from metabolism is H2S
Collage of Science/ Kufa University
Fourth Level
L. Assistant Rawa abdul Redha Aziz
FOOD MICROBIOLOGY LAB 5
Microbial spoilage
Depending on oxygen availability, meat spoilage by micro-organisms can
manifest itself as follows:
Oxygen
Present
Microbial
agent
Aerobic
bacteria
Symptoms





Present
Yeasts




Present
Molds




Absent
Anaerobic
bacteria



Surface slime
Discoloration
Gas production
Change in odor
Fat decomposition
Surface slime
Discoloration
Change in odor and taste
Fat decomposition
Sticky and "whiskery" surface
Discoloration
Change in odor
Fat decomposition
Putrefaction and foul odors
Gas production
Souring
Lab Procedures
Collage of Science/ Kufa University
Fourth Level
L. Assistant Rawa abdul Redha Aziz
Collage of Science/ Kufa University
FOOD MICROBIOLOGY LAB 5
Fourth Level