Milk Quality Standards

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Milk Quality Standards
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Milk and Milk Quality

• Excellent media for bacteria
• One of the safest foods
• Most tested food product
• Easy to sample
• Easy to measure quality
• Pasteurization
• Good at killing bugs but shouldnt rely on it to
  make contaminated milk better

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Keys to Milk Quality

• Healthy cows
• Mastitis nutrition management
• Clean environment
• Clean and functioning milking equipment
• Rapid cooling
• Keep it cold

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Pasteurized Milk Ordinance

• PMO
• Federal laws regarding milk production
• Developed by the FDA
• In conjunction with the Interstate Milk Shippers
• Concern is public health
• Set of standards for the production and handling
  of Grade A raw and pasteurized milk
• Across US

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PMO Includes

• Milk quality sampling and testing
• Antibiotics residues
• Adulteration
• Penalties
• Stable parlor and milk house design and
  construction
• Cleanliness personnel feed storage water
  supply
• Milking equipment and utensils
• Mastitis and udders cleanliness
• Drug usage and storage
• Farm truck and plant inspections
• Licensing and permits

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What Milk Standards Do They Set

• Somatic cells
• No greater than 750000/ml
• Bacteria limits
• No greater than 100000/ml
• Drugs
• No positive results on residue tests
• Temperature
• Cooled to 50 F or less within 4 hr of the start
  of first milking
• Cooled to 45 F or less within 2 hours after
  milking
• Blend temp does not exceed 50 F after that

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Raw Milk Tests

• Temperature
• lt45 F degrees
• Somatic Cell Count
• Standard Plate Count
• Lab Pasteurized Count
• Coliform Count
• Preliminary Incubation Count
• Antibiotics

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Other Milk Tests

• Flavors and Odors
• Freezing Point Depression
• Measures for added water
• Milk freezes at 0.530 to 0.566 C
• Acidity
• Brucellosis Ring Test
• Sediment
• Fat and Protein - Pricing

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Wisconsin Study of SCCs (1998)

• 168989 monthly bulk tank samples
• Average SCC was 290000
• 4500 farms had SCC lt200000
• 1800 farms had SCC lt130000
• 25 of farms had SCC gt400000
• Good if SCC lt200000

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Bulk Tank SCC and Percent of Cows Infected with
Mastitis Pathogens
Eberhardt et. al. 1979
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Standard Plate Count

• Referred to as the Bacteria Count or SPC
• Good overall measure of milk quality
• Difficult to diagnose problem from a single test
• Run monthly or more frequently
• Determines the number of colony-forming units in
  one milliliter of milk
• Incubated at 90 F for 48 hours
• High bacteria counts come from
• Inside the cow - Mastitis
• Outside the cow - Udder prep
• Inside the equipment - Sanitation
• Growing in the tank - Cooling

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Evaluation of SPC

• Bacteria counts dont go up without a reason!
• PMO Standards - Must be under 100000/ml
• Plants may set lower standards - Bonuses
• Virginia study
• 59 of farms below 5000 cfu
• 76 of farms lt10000
• 87 of farms lt20000
• Reasonable goal lt5000/ml
• Problem if SPC gt10000/ml

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Causes of High SPC

• Usually caused by sanitation or cooling problem
• Improper cleaning
• Film or milk stone build up inside milking
  equipment
• Sanitizing of equipment
• Milking dirty cows
• Excessive use of water in milking prep
• Inadequate cooling
• Improper handling of sample prior to reaching the
  lab
• Rarely caused by mastitis organisms

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Bacteria Counts Associated with Prep Techniques
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Lab Pasteurized Count

• LPC or Thermoduric Count
• Milk is pasteurized before plate count
• Identifies organisms that survive pasteurization
• Organisms that spoil milk after pasteurization
• Mastitis organisms usually dont survive
• NY Study
• 60 of farms lt200 cfu
• 40 of farms lt80 cfu
• Evaluation
• Excellent milk lt10 cfu
• Should be below 200 cfu

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LPC Interpretation

• Most associated with unclean equipment and poor
  sanitation
• Leaky pumps
• Old pipeline gaskets and inflations
• Milk stone deposits

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Coliform Count

• Media only grows Coliform bacteria
• Coliforms Manure
• How do they get in the milk
• Can also grow on milk handling surfaces
• Evaluation
• Should be less than 10 cfu/ml
• Count of 100-1000 - Cow cleanliness and prep
  problem
• gt1000 growth on milk surfaces
• NY Study
• 30 lt10 cfu
• 20 gt100 cfu

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Preliminary Incubation Count - PI

• Milk is incubated for 18 hours at 70 F
• Simulates poor refrigeration
• Psychrotrophic bacteria
• Off-flavors and reduced shelf life
• Measure of raw milk keeping quality
• Sanitation practices
• Not associated with mastitis
• Evaluation Good lt10000 Up to 50000 is OK
• NY Study
• 30 lt14000 cfu
• 10 lt8000 cfu

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Causes of High PI Count

• Equipment cleanliness and sanitizing
• Slow cooling of bulk tank
• Temperatures above 40 F
• Debris build up in plate coolers and chillers
• Dirty udders
• Poor sanitation during udder prep
• Contaminated water supply
• Lack of sufficient hot water to clean equipment
• Improper drainage of lines
• Cracked rubber parts
• Cows infected with Streptococcus organisms

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Antibiotic Testing

• Every tank has sample drawn
• Truck is not allowed to unload at plant until
  test is negative
• If hot sample is found tank samples are tested to
  locate source
• Maximum legal allowable limits set for each drug
• Penicillin 10 ppb
• Oxytetracycline 30 ppb
• Sensitivity levels of each test is usually below
  this limit
• Charm II - penicillin gt4.8 ppb

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Causes of Off-Flavors

• Bacterial
• Absorbed
• Chemical

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Milk Off-Flavors

• Rancid fat breakdown
• Oxidized - cardboard
• Feedy
• Cowy - manure
• Cooked
• Acid/sour - bacteria
• Flat watery

• Malty
• Salty mastitis
• Weedy
• Foreign disinfectants
• Unclean - dirt

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Farm Inspection

• Milk Plant
• State Department of Agriculture
• USDA-APHIS
• Twice yearly inspection of
• Cows
• Equipment
• Housing
• Water supply

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The End