Microbiology Basics (Part 1)
Dr. John Marcy
Professor and Poultry Processing Specialist
Center of Excellence for Poultry Science
University of Arkansas
To register for more webinars is this series, visit:
http://indigenousfoodandag.com/food-safety/
For more information, call: (479) 575-4434
Microbiology Basics (Part 1)
Dr. John Marcy
Professor and Poultry Processing Specialist
Center of Excellence for Poultry Science
University of Arkansas
INPUTS
¡ Food
¡ Water
¡ Temperature
¡ Light
¡ Air
Microbial Life
Biosecurity – from humans, livestock,
wildlife, or other farms
¡ Contamination could also occur from rodents
or flies in a facility
¡
¡
The president of Acme Markets, John Park, was ruled personally and
criminally liable for failing to maintain sanitary facilities.
¡
When FDA visits, they will spend time looking for places where
water/moisture will allow for bacterial growth.
¡
They will also be looking for any evidence of rodent or insect infestations.
¡
They will probably do microbial swabbing looking for signs of human
pathogens in your establishment.
¡
You may get a Form 483 which lists any observations that the
investigator believes may constitute a violation of the Food Drug and
Cosmetic Act.
¡
Form 483 puts the company on notice and the company should respond
in writing with a corrective action plan and then implement that plan.
Disinfectants kill the vegetative form of
microorganisms, but do not necessarily kill
spores
May be used in facilities where birds grow
Sanitizers and antimicrobials used in processing
plants reduce the risk of Salmonella
Vegetative bacteria
¡ Brucella spp.
¡ Campylobacter spp.
¡ Pathogenic E. coli
¡ Listeria monocytogenes
¡ Mycobacterium bovis
¡ Salmonella spp.
¡ Shigella spp.
¡ Staphylococcus aureus
¡ Streptococcus group A
¡ Vibrio spp.
¡ Yersinia enterocolitica
Sporeformers
¡ Bacillus cereus
¡ Clostridium botulinum
¡ Clostridium perfringens
Note: Sporeformers grow as
vegetative cells!
Spores and
vegetative cells
of B. cereus
Photo courtesy of K.M.J. Swanson
Preventing Bacteria from Growing
4,500,000
4,000,000
3,500,000
Natural Numbers on a Arithmetic Scale
3,000,000
10
hours
2,500,000
2,000,000
1,500,000
1,000,000
500,000
0
3 hours
Time
10,000,000
1,000,000
Natural Numbers on a Log Scale
100,000
10,000
1,000
100
10
1
3 hours
Time
10 hours
For microbiological systems
¡
¡
¡
Is 3 different than 6?
Is 30 different than 60?
Is 30,000 different than 60,000?
For microbiological systems
¡
¡
¡
Is 0.48 log10 different than 0.78 log10?
Is 1.48 log10 different than 1.78 log10?
Is 4.48 log10 different than 4.78 log10?
Boiling
Water
¡
Range of Growth (32-212+F)
¡
Pathogen Growth (41-130F)
Themophile – heat loving
Body
Temperature
Water
Freezes
Frozen
Food
Temperature Danger Zone
41 – 135 F (5-57 C)
Mesophile – moderate temp loving
Psychrotroph – cold tolerant
Psychrophile – cold loving
Freezing is not an effective way to make
foods safe
Some bacterial cells can be destroyed, some
"injured", some unharmed
Freezing used to destroy parasites
(-15C, 20 days for Trichinella spiralis)
All bacteria require water (growth &
reproduction)
Essential solvent, biochemical reactions
Definitions:
a) ratio of wvp food/wvp pure water P/Po
b)
c)
ERH/100
For an ideal solution:
moles solvent/(moles solvent + solute)
n2/(n1 + n2)
0.98 - 0.995 is ideal
range .90-1.0 (can grow as low as .85)
lower Aw causes a cells to
- lose intracellular components and water
Optimal pH for growth = 7.0 (6.0 – 8.0)
Range:
Pathogens - 4.6 -9.5 (4.6 - 7.0 in foods)
Spoilage - 1.5 - 9.5 (1.5 - 7.0 in foods)
Strong inorganic acids (HCL) differ greatly
from weak organic acids (acetic, lactic)
1
2
3
4
1: Obligate Aerobe
2: Facultative Anaerobe
3: Aerotolerant Anaerobe
4: Strict Anaerobe
5: Microaerophilic
5
“Hurdles Concept”
Predictive microbiology
The study of interactive
effects of factors effecting
microbial growth
uAdditive effects
uSynergistic effects
uAntagonistic effects
¡
The process for getting food to the consumer
will produce a product that is wholesome and
nutritious, but may not be free of bacteria that
cause spoilage & illness
¡
Challenge: To produce a product that has the
lowest possible risk of making someone sick
with enough shelf life for distribution and tastes
good.
¡
Someone else will likely test the integrity of your
product. Consumer testing is 100%
Microbiology Basics (Part 1)
Dr. John Marcy
Professor and Poultry Processing Specialist
Center of Excellence for Poultry Science
University of Arkansas
To register for more webinars is this series, visit:
http://indigenousfoodandag.com/food-safety/
For more information, call: (479) 575-4434