Flashcards in Milk Hygiene (final material) Deck (29)
What is cow milk composed of?
What is Grade A milk defined as?
Defined and regulated by the Pasteurized Milk Ordinance
for liquid consumption and any milk in interstate commerce
*most cheese, butter, ice cream, and other dairy products are made from Grade A milk
T/F: Milk is bacteriologically sterile
Bacteria in the teat canal
Bacterial on the skin of the teat (staph/strep)
Post harvest contamination
What are other (non-bacterial contaminants) that can be found in milk?
Antibiotics and other drugs
What steps are taken on the farm, following the PMO, after milking?
Cooled to 45F within 2 hrs
Somatic cell count must be less than 750,000/ml
Bacterial count must be less than 100,00 ml
No drug residue
What are some causes of high bacterial counts within milk?
Milking dirty cows
Cleaning water temp and vol.
Cracked rubber parts
Biofilm in bulk tank
Inadequate cleaning of bulk tank
What bacteria present in milk would lead you to suspect fomite contamination from human hands?
Sanitation begins with the _________
1.Milking parlor and all the equipment inside should be easy to clean
2. Yard/pasture for cows should have no standing pools of water or feces
3. Appropriate bedding for cows
Sanitation also applies to _____ and _________
Cows and personnel
Before milking, what should be done to the teats?
They should be sanitized and dried
Under the PMO, how long may milk be stored in the bulk tanks on the farm?
Up to four days
*these are refrigerated
How is milk transported?
Insulated tanker trucks
The tanker load is tested for antibiotic residues before it is unloaded
T/F: Tanker trucks transporting milk may pick up from more than one farm
What occurs at the milk receiving station?
Milk is analyzed for bacteria, somatic cell counts, and composition (fat and other components)
What is the clarification process of milk?
Clarifier = remove sediment
Milk is pumped through a centrifugal device to remove large particulate matter (dirt, straw, blood, somatic cells, manure)
Does the clarifier remove bacteria from milk?
What is the function of the milk separator?
Separates milk with different amounts of fat
This is also based upon cetrifugation
What is the basic process of pasteurization of milk and why is it done?
Using heat (for certain periods of time) to kill common pathogens in milk, inactivate enzymes in milk, enhance shelf life
Pasteurization is currently based on the thermal death of what pathogen?
What is batch pasteurization? What temp is used and for what time?
An entire vat is heated and held at temperature for the appropriate length of time.
63C/145F for 30 min
What is the process of continuous flow pasteurization?
Milk flows through a heated tube, with a carefully monitored transit time and temperature
results in less of a "cooked" flavor than batch methods
Temps range from 72C/161F - 100C/212F for short periods of time (12sec - 1 sec - 0.5sec)
After pasteurization, what temp is milk cooled to and maintained at?
less than 45F
should contain less than 20,000 bacteria/ml and less than 10coliform bacteria/ml
phosphatase test must be negative
T/F: For cheese or cottage cheese, pasteurized milk has no bacterial limit; just coliform limit of less than 10/ml
Where do microbes found in cow milk come from?
Mastitis or systemic infections
Dirt/mud, feces, hair on exterior
What percentage of dairy cow may produce abnormal milk due to subclinical mastitis at any one time?
milk will be increased in blood proteins and leukocytes and there will be a decrease in production
What should the somatic cell count of healthy milk be?
less than 100,000/ml
automated machine counters are used for this data
What somatic cell count may you expect in a subclinical case of mastitis? And in a clinical case?
Subclinical = greater than 200,00
Clinical = SCC in the millions **30% loss in milk production per day
What is the legal maximum SCC in the bulk milk tank?
750.00 cells/ml - USA
(limits are lower in Europe and Canada)
*mean for US dairies = ~230,000 cells/ml
*lower in winter than in summer, in western US and large dairy herds