Ch 4 Microbiological Sampling And Testing Flashcards
What type of bacteria can grow under refrigerated conditions?
Psychotropic
45F or less
What is a gram stain?
A test that helps to determine gram positive or gram negative organisms
Gram negative lose the violet color of the stain; Gram positive retain the color
What bacteria are considered Gram-negative?
Pseudomonas-the most common and most harmful for milk quality
What characteristic of gram negative psychrotropic bacteria makes them a hazard for both raw and Pasteurized milk?
- can grow under refrigerated conditions
- enzymes released by the bacteria can be heat stable and survive pasteurization
What are the 9 organisms of concern as outlined by the Compliance Policy for FDA?
- Salmonella
- Shiga toxin producing E Coli
- E Coli
- Campylobacter Jejuni
- Yersernia Enterocolitica
- Clostridium botulinum
- Enterotoxiginic Staphylococcus
- Bacillus Cereus
- Listeria Monocytogenes
What is the source of salmonella; where can it be found in the dairy chain?
Can be shed in the feces of animals; can be found in pastures or milking parlors
How many salmonella organisms can cause an illness?
15-20 organisms
What is an infected dose of shiga toxin EColi?
10-100 organisms
Which organism is not organically found in milk so when present, is a sign of cross contamination?
E. coli
What does the presence of E. coli in a milk sample indicate?
Contamination from animal or human feces
How many organisms of campylobacter jejuni is needed for illness?
400-500
What are the possible sources of campylobacter jejuni in milk?
Either from feces or an infection in the udder that is passed on to the milk
Which organism is considered to be a neurotoxin?
Clostridium botulinum
Is Clostridium botulinum killed by pasteurization?
No
Can survive pasteurization. Destroyed at 176F for 10 minutes
What is a source of enterotoxigenic staph in milk?
Mastitis
poor/unclean handling of milk or cheese throughout the cheese making process
What threshold for staphylococcus aureus indicates unsanitary conditions?
Greater than 10,000 cfu/g
What is cfu/g?
Measurement of viable bacterial cells in a sample
Colony-forming units per gram
What is the threshold for illness of Bacillus Cereus?
1 million cfu/g
Where can listeria be found?
Soil, water, animals (including cattle)
Can grow in cold environments, including refrigeration
What is the tolerance for L. Monocytogenes?
None-there is no tolerance for this organism in milk/cheese
What is SPC?
Standard Plate Count
What is a DMC?
Direct Microscopic Count
15 minute rapid microbial test. Both dead and living organisms are counted, so may have a higher total
What is the SPC limit for Grade A milk? Commingled or Grade B?
Grade A: 100,000 cfu/g
Grade B: 300,000 cfu/g
For optimum shelf life, what are the desirable SPC counts at a farm? At a milk processor level?
At farm: 10,000 cfu/ml
Processor: 50,000 cfu/ml
What can be indicators of high colifirm counts?
Poor hygiene
Poor animal housing
Muddy/rainy conditions
Improper cleaning and sanitizing
Is there a federal standard for Coliform counts in raw milk or raw milk products?
No!
Individual states may have regulations
What is the count of coliforms in pasteurized milk?
Less than 10 cfu/g
These are easily killed by pasteurization
What are coliforms?
Group of organisms used to indicate sanitary conditions
What is the incubation time for a SPC for psychrotropic bacteria?
10 days at 45F
What quicker test is used, along with a SPC, to test for psychrotropic bacteria in raw milk?
A PIC (preliminary Incubation Count); results ready in 24-36 hours at 45F
What does the presence of thermoduric bacteria indicate?
The thoroughness of cleaning/sanitizing of equipment or unsanitary production practices
What test is used to find thermoduric bacteria?
Laboratory pasteurization count
According to FSMA, what three protocols should be in place for food safety?
- GMPs (Good manufacturing practices)
- HACCP plan
- testing of product after 60 day aging window elapsed
What are the Big 4 organisms you should test for when using raw milk for cheese?
- salmonella
- listeria
- STEC E Coli (shiga toxin producing
- enterotoxigenic Staph
What is the purpose of an environmental monitoring program?
To detect the presence of listeria in the production facility
What are some specific areas of the production facility that should be tested regularly as part of the environmental monitoring program?
- brine tanks
- drying racks
- aging rooms
- air quality
What is an ATP test and when is it performed?
Adeonsine Triphosphate
Rapid swab test that indicates food residue, microorganisms (alive or dead) that may be on a surface.
Equipment Should be tested prior to the start of the day’s production
What are the 4 general zones in a production facility?
- Zone 1: food contact surfaces (FCS)
- Zone 2: non food contact surfaces (NFCS)
- Zone 3: area that directly surrounds zone 2
- Zone 4: areas outside of production areas
What are examples of a Zone 1 area?
- all pasteurization lines and equipment
- vat/ bulk equipment
- knives/ hoops/ utensils
- packaging
- ANYTHING THST COMES IN DIRECT CONTACT WITH FOOD
What are examples of a Zone 2 area?
PPE worn by employees
Pipes/hoses
Catwalks
Control panels
Draining tables
Anywhere that milk/or whey can contaminate
Anywhere warm or wet or humid
What are examples of a Zone 3 area?
Packaging areas that are NFCS
Dollies/carts
Trash cans
Hand sinks
Employee shoes
Forklifts/pallet jacks
What are examples of a Zone 4 area?
Areas that are outside of production rooms
Warehouses
Dock
Break rooms
Bathroom/locker room
In what zones are you able to test for listeria?
All!
According to the 2008 FDA guidance for control of listeria, how often should you test Zone 1:
Samples from all FCS at least once a week. If using a representative set, plan so that all areas are tested at least once a month.
Should collect from at least 5 sites
According to the 2008 FDA guidance for control of listeria, how often should you test Zone 2:
Collect samples at least once every two weeks. If using a representative set, plan so that all areas tested at least once a quarter.
If consistent negative results, make sure that the collection sites are rotated
According to the 2008 FDA guidance for control of listeria, how often should you test Zone 3 &4:
At discretion if the producer, but recommended monthly.
If found in areas 1 or 2, increase the sampling of these areas
Where should testing of zones be primarily focused as a form of prevention?
Zones 2-4. If it’s reached Zone 1, it’s too late!!!
What does a standard plate count show?
Only the numbers of bacteria not the specific bacteria in the sample
Other than the cheese itself, what else should be tested for contamination?
All ingredients (spices, flavorings, etc)
Packaging
Can obtain a COA (certificate of Analysis) from purveyors of ingredients and/or packaging
When testing for contamination, when should samples be taken?
When pathogen population should be at it’s highest
What is a determining factor in the frequency of finished product testing?
The nature of the product (soft cheese vs. aged cheese)
In 2015, which 3 food retailers made the Artisan Cheesemaker Level One Food Safety Audit and Supplier Checklist?
Whole Foods Market
Wegmans
Lund Food Holdings
