Milk Hygiene (final material)

Question 1

What is cow milk composed of?

Answer 1

Fats
proteins
Carbohydrates
minerals
vitamins
water (87%)

Question 2

What is Grade A milk defined as?

Answer 2

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

Question 3

T/F: Milk is bacteriologically sterile

Answer 3

FALSE

May contain: 
Mastitis organisms
Bacteria in the teat canal
Bacterial on the skin of the teat (staph/strep)
Post harvest contamination

Question 4

What are other (non-bacterial contaminants) that can be found in milk?

Answer 4

Antibiotics and other drugs
Pesticides
Colostrum
Off-flavors
other aldulterants

Question 5

What steps are taken on the farm, following the PMO, after milking?

Answer 5

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

Question 6

What are some causes of high bacterial counts within milk?

Answer 6

Milking dirty cows
Cleaning water temp and vol.
Cracked rubber parts
Dirty gaskets
Biofilm in bulk tank
Inadequate cleaning of bulk tank
Mastitis bacteria

Question 7

What bacteria present in milk would lead you to suspect fomite contamination from human hands?

Answer 7

Staph. auerus

Question 8

Sanitation begins with the _________

Answer 8

Premises

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

Question 9

Sanitation also applies to _____ and _________

Answer 9

Cows and personnel

Question 10

Before milking, what should be done to the teats?

Answer 10

They should be sanitized and dried

Question 11

Under the PMO, how long may milk be stored in the bulk tanks on the farm?

Answer 11

Up to four days

*these are refrigerated

Question 12

How is milk transported?

Answer 12

Insulated tanker trucks

The tanker load is tested for antibiotic residues before it is unloaded

Question 13

T/F: Tanker trucks transporting milk may pick up from more than one farm

Answer 13

TRUE

Question 14

What occurs at the milk receiving station?

Answer 14

Milk is analyzed for bacteria, somatic cell counts, and composition (fat and other components)

Question 15

What is the clarification process of milk?

Answer 15

Clarifier = remove sediment

Milk is pumped through a centrifugal device to remove large particulate matter (dirt, straw, blood, somatic cells, manure)

Question 16

Does the clarifier remove bacteria from milk?

Answer 16

NO

Question 17

What is the function of the milk separator?

Answer 17

Separates milk with different amounts of fat

This is also based upon cetrifugation

Question 18

What is the basic process of pasteurization of milk and why is it done?

Answer 18

Using heat (for certain periods of time) to kill common pathogens in milk, inactivate enzymes in milk, enhance shelf life

Question 19

Pasteurization is currently based on the thermal death of what pathogen?

Answer 19

Coxiella burnetii

Question 20

What is batch pasteurization? What temp is used and for what time?

Answer 20

An entire vat is heated and held at temperature for the appropriate length of time.

63C/145F for 30 min

Question 21

What is the process of continuous flow pasteurization?

Answer 21

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)

Question 22

After pasteurization, what temp is milk cooled to and maintained at?

Answer 22

less than 45F

should contain less than 20,000 bacteria/ml and less than 10coliform bacteria/ml

phosphatase test must be negative

Question 23

T/F: For cheese or cottage cheese, pasteurized milk has no bacterial limit; just coliform limit of less than 10/ml

Answer 23

TRUE

Question 24

Where do microbes found in cow milk come from?

Answer 24

Mastitis or systemic infections
Dirt/mud, feces, hair on exterior
Dusts, aerosols
Milking equipment
Personnel
Water

Question 25

What percentage of dairy cow may produce abnormal milk due to subclinical mastitis at any one time?

Answer 25

5-10%

milk will be increased in blood proteins and leukocytes and there will be a decrease in production

Question 26

What should the somatic cell count of healthy milk be?

Answer 26

less than 100,000/ml

automated machine counters are used for this data

Question 27

What somatic cell count may you expect in a subclinical case of mastitis? And in a clinical case?

Answer 27

Subclinical = greater than 200,00

Clinical = SCC in the millions **30% loss in milk production per day

Question 28

What is the legal maximum SCC in the bulk milk tank?

Answer 28

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

Question 29

What is the number one cow side mastitis test?

Answer 29

California mastitis test (CMT)

*other tests include - electrical conductivity, mammary associated amyloid A, Bacterial cultures