1. Madison Chemical Food Division
Microbiology
Terry Willis-Senior Advisor-Food Division

2. What is Microbiology? Micro=microscopic / Biology=study of life
So it is the study of microorganisms.
Microorganisms are single cell organisms and the smallest form of life that are present everywhere in our environment.
1 bacterial organism can multiply to over 2 million in 7 hours under the right environmental conditions.
In food processing, microorganisms play major roles
in processing, preservation, spoilage, and food-borne
illness.

3. 5 Basic Groups
Bacteria
Mold
Yeast
Viruses
Protozoans

4. Good Microorganisms
Some microorganisms are used in food processing to produce the final cultured product.
Buttermilk
Sour Cream
Cheese
Yogurt
Sauerkraut
Pickles
Soy Sauce
Sausage

5. Harmful Microorganisms
Harmful organisms can cause product spoilage or can be pathogens to humans.
Some Typical Spoilage Organisms:
Pseudomonas
Bacillus
Penicillium
Lactobacillus
Rhodotorula
Cladosporium

6. Harmful Microorganisms (Cont.)
Cause illness in humans
Mostly gastrointestinal
Mainly affects young, elderly and immunocompromised
Examples are:
Salmonella Campylobacter
Listeria Cyclospora
E. Coli Shigella

7. Factors Affecting Microbial Growth
Food
Temperature
Moisture pH
Oxygen
Time

8. Factor - Food Like all living organisms, bacteria need food to grow:
Insoluble Organics
Protein
Carbohydrates
Fats and Oils

9. Factor - Temperature Temperature controls the growth rate.
Bacteria have minimum, optimum and maximum temperatures for growth.
Freezing does not kill bacteria.
Heating can kill most cells but not all spores.

10. Factor – Temperature (Cont.)
Growth Ranges
Psychrotrophs 32°F – 85°F
Mesophiles 75°F – 115°F
Thermophiles 114°F – Higher
Thermoduric Able to survive pasteurization

11. Factor - Moisture All microorganisms require water.
Very low water availability (Such as peanut butter, cereal, dried fruit)
They die or become dormant.
Spoilage of a product mainly depends on available water content.

12. Factor - pH Common Foods
Disease causing bacteria will not grow below pH 4.6 (example: Listeria and Salmonella)
Not necessarily true of spoilage organisms
(example: Lactobacillus)
Acid
Neutral
Alkaline
Tomatoes
4.2
4.6
Raw Meat
5.8
Egg Yolk
6.4
Egg White
8.0

13. Factor - Oxygen 2 types bacteria classifications
Aerobic – bacteria that thrive in presence of oxygen
Anaerobic – bacteria that thrive where there is no oxygen
Canned goods
Vacuum packages
Modified Atmospheric Packages (MAP)
Products heated for long periods of time

14. Factor - Time
There are four life stages of bacteria and each moves through those stages at varying speed, depending upon the proper combination of food, temperature, moisture, pH and oxygen.
# Bacteria
Time
lag
log
stationary
death

15. Biofilm Bio=life / Film=layer - so it is a layer of life
These are communities of bacterial cells that adhere to surfaces and each other.
They secrete a glue-like material called polysaccharide that holds them together and protects them.
The bacteria will continue to multiply within this protective layer to a point that it cannot contain all the organisms and equipment/product contamination occurs.
Sporadic high swab counts can be an indicator of a biofilm problem.

16. Biofilm
Growth and constant contamination source.

17. Biofilm
Free-floating (planktonic) bacteria that are not attached to surfaces and protected are easier to remove and to eliminate with sanitizers.
Chemicals and sanitizers cannot penetrate the polysaccharide film to kill the bacteria.
Planktonic but will soon attach
Polysaccharide

18. Biofilm Practices that may enhance formation:
Short cuts in proper cleaning procedures
Proper cleaning and preventative measures must include a balance of the proper chemical, time, temperature, concentration and application (physical action).
Proper sanitizing as well as the proper type sanitizer are critical
Equipment design can greatly affect the formation of biofilms if there are areas that are difficult to clean or areas that tend to pool soil, water, etc.
Worn equipment as well as improperly repaired equipment. Things like rough welds, gaps in seams, cracked surfaces, rivets, etc.

19. Biofilm Practices that may enhance formation (cont.):
Areas that may not be cleaned daily such as walls, floors, drains, etc. can tend to provide quicker biofilm formation because bacteria and soil are not thoroughly removed thus the bacteria grow and start forming the polysaccharide film quickly.
Longer processing times have forced shorter cleaning times (often 4 hours or less), therefore less scrubbing can be done.
CIP systems are less prone to biofilm because the turbulence acts as a scrubbing mechanism. Areas that can be biofilm problems in CIP are dead spaces or low flow areas.
Extended processing times also extend times between cleanup (processing for 4-5 shifts allowing cleanup only every day and a half or even more).

20. Control Measures Raw Materials
Set micro standards for raw materials and check incoming product. Inspect suppliers occasionally.
Properly store ingredients
Coolers, freezers or dry storage
Quickly rotate ingredients
“First In, First Out”
Proper separation of ingredients
“Like with like”

21. Control Measures Processing Use proper parameters Heat inactivation
Time / temperature relationship
Storage temperature

22. Control Measures Employees Proper personal hygiene
Utilize Good Manufacturing Practices (GMPs)
Effective Sanitation Cleaning and Sanitizing
Proper Maintenance of Equipment
Repair cracks and improper welds
Replace worn or torn seals and gaskets