Milk (Exam 2) Flashcards
What are the different types of milk harvesting housing?
Tie stall barn: pipeline system above cow to carry milk from udder to bulk storage; stay in dry feed lots/barn; into holding pen; into milking parlor with doors open, walk in voluntary, door closes automatically
Parallel parlor: straight back
Herringbone parlor: angled
Rotary parlor
All these styles have pipelines below cows = good for milk as gravity pulls down and don’t ruin the quality of milk
How is milking prepped?
Stimulation of milk let down and pre-stripping
Udder clipped/hair singed
Pre-dip
Single cloth towels
Backflush
Add Machine
Machine automatically released
What occurs with stimulation of milk let down and pre-stripping?
Allow milk to squirt out to evaluate (45-60s)
Cows with mastitis are held out and not milked into the lane (puss in milk)
Why/how are udders clipped/long hairs singed?
With cool flame
To prevent dirt and debris introduced in milk
What is the purpose of pre-dip?
Stimulates teats and allows milk to come down (0.5% iodine)
What is the purpose of single-cloth towels?
Removes pre-dip after 30 seconds of contact time
Teats clean and ready for machine application
Define: Backflush and Machine Add On
2 vacuum system and massaging system
Pulsation mimicking calves
If suction too hard, start pulling blood and damages cap, ducts, and teat
What is the purpose of the machine automatically releasing?
Measures milk let down and identifies when low milk volume
What steps are taken to confirm that the cow is healthy and that the milk she produces is wholesome for consumption?
Each cow’s udder evaluated for heat, swelling, and pain to determine if milk is suitable for milking
Pre-stripping allows milk to squirt out before milking to evaluate the milk
Testing for mastitis of other infectious diseases that could lead to spoilage/bad/taste/dangerous milk
What is the Pasteurized Milk Ordinance?
PMO
Make high quality product with low pathogens/bacteria
Govern design and maintenance of dairy farms and processing plants to make sanitation and milk quality uniform across state lines (adopted by most states
What regulations are in the pasteurized milk ordinance?
Standard for milk harvest, storage, transport, cow facilities, equipment specification, cleaning processes
Inspections and oversights
Testing milk
Allowable limits for test results
Pasteurization standards
Packaging and handlin
How does mastitis affect the cow, the milk, the quality of the milk, and the safety of the milk?
Inflammation of mammary gland = influx of inflammatory cells and mediators
Most commonly due to bacterial infection
Most common infectious disease of lactating cows
Cause disease in cow = cow health problem
NOT FOOD SAFETY PROBLEM
YES FOOD QUALITY PROBLEM = increase somatic cell count, milk composition changes
Abnormal milk/milk quality
Most common reason for antibiotic use in dairies (drug residue is major concern, withdrawal time after use)
What are the clinical signs of mastitis in cows?
Local infections of udder = redness, swelling, heat, pain
Milk = clots, thick/thin, color
Systemic = fever, tachycardia, diarrhea, weakness, death
What are the somatic cell tests?
California mastitis test: rapid; add milk to wells, add reagent, color change test = coagulates somatic/enucleated cells
Electronic SCC: test large numbers of individual cows (commercial dairies) monthly = look at summary (% up/down, compare parity/age, % herd with low SCC)
What are the normal/high SCC values?
Normal: <250k
High Quality: <100k
Mastitis: >300K
How is mastitis managed?
Bacterial culture: key to appropriate management of problem herds, determine why high SCC (sample from each teat and test)
Intramammary antibiotic infusion: routine treatment (inject locally, better tx than systemic)
What are the bacterial sources of milk contamination?
Teat skin/canal (commensals)
Machine liners/tubers (improper procedures, cleaning, water temperature)
Mastitis
Systemic infections
Contaminants
What are zoonotic pathogens in milk?
Pasteurization prevents disease spread!
Salmonella
E. coli
Campylobacter
MAP (feces)
Cryptosporidum
What are bacterial pathogens that threaten animal health?
Mastitis
What are bacterial pathogens that threaten milk spoilage?
Majority of bacteria in milk = spoilage bacteria
Psychotropic bacteria (spoilage)
Thermoduric bacteria (reduce shelf life) = micrococcus, microbacterium, lactobacillus, bacillus, clostridium
How is milk moved on the farm and from the farm through the processing system?
Modern milking system = use pipelines to move milk faster, reduce exposure to air, chilled faster
Move to receiver tube to cooling tubes (plate coolers) to tank room/bulk tank
Agitator running to keep milk at right temp
Loaded onto trucks to be processes at milk plant
What processes are used to assure highest milk quality?
Cooling/chilling to prevent microbial growth/spoilage (chilled and stored <40F)
Filtered to remove debris
Removed from farm to processing within 48 hours
Less exposure to air
Pipes moving downwards to not impact quality of milk
Pasteurization
How have technological advances improved milk quality?
Automatic milking systems robotic milkers
Dairy tech pasteurizer
Define: Dairy Tech Pasteurizer
Turbulent to take out clumps of pathogens and kill them off
More pipelines to increase movement of milk under certain temperatures to deliver to pasteurization
HTST method of pasteurization: milk in tank at low temperature (<40F) leaves from one tube to regenerator
Adjacent milk pipe is hot, leaving pasteurization and back to tank (low temp): hot milk warms up cold milk and vice versa
Additional heating phase added to bring milk >72F held for 15 seconds, then regenerated back to cooler temps
Energy efficient and neutralize pathogens
What is the purpose of quality and safety testing of milk?
Every tanker or milk is tested
Single most tested food product, required by PMO
Evaluated for both safety and quality
What tests are done for milk quality/safety?
Diagnostic milk culture
Somatic Cell: mastitis and milk quality
Residue testing: Beta lactams (abx)
Milking ring test: burcellosis
What are the standard methods of quality testing of bulk milk?
Standard plate count
Preliminary incubation count
Lab pasteurized count
Coliform count
Sediment (dirt)
Freezing point (dilution)
Acidity, rancidity (bacterial/damage to milk)
Odor, color
Temp at pick up (<40F)
Describe standard plate count (SPC)
Raw bacterial count of milk
Ideal <5k cfu/ml, may have problems at >10k cfu/ml, legal limit 100k
Strong relationship with ‘keeping’ quality of milk = leads to bacterial spoilage
Describe preliminary incubation (PI) count
Incubate at 55F for 18hrs then plate for SPC
Measures: psychotrophic bacteria (in low temps, higher change of spoilage), raw milk keeping quality, sanitation practices on farms
Ideal <10k, acceptable <50k cfu/ml
Describe lab pasteurized count (LPC)
Follow up to SPC
Incubate at 145F for 30min then place for SPC
Measures: thermoduric bacteria (reduce shelf life), equipment cleanliness, effective clean up (improper water temp, cleaner concentration, malfunctioning air injector), old rubber parts
Ideal <100-200, excellent equi hygiene <10
Describe coliform count
Common fecal contaminants, test if water or milk has fecal contaminants (all bacteria, not just E. coli)
90F for 24hrs on selective media
Indication of sanitary production practices: cow, machine cleanliness, effective clean up
Ideal <10, acceptable <100cu
Why are milk somatic cells measured and what do they tell us?
Help improve milk quality and alert you to early signs of mastitis
Helps quickly identify and treat infected animals and protect herd health and milk quality by preventing spread of bacteria
Somatic cells: nucleated cells, lining cells, inflammatory cells
What is the role of pasteurization?
Process of heating every particle of milk in eqeuipment to specific past time/temp combination to reduce pathogens/bacterial load
Time/temp standards set for TB, brucella, coxiella, effective for other typical pahtogens
Standard commercial process does NOT sterilize, still have bacteria that leads to spoilage, enough removed to increase safety/shelf life
What does pasteurization do to milk?
Prolongs shelf life (reduces spoilage bacteria)
Changes taste (not content of primary nutrients
What is the time v temp relationship of pasteurization?
Higher temp = less time to reduce bacterial numbers in milk
Define: long time holding pasteurization
140 degrees for 20 min
Neutral zone
Common
Define: high temp, short time pasteurization
Heat milk to higher temp (161F) for short period (15s)
Common
Define: ultrapasteurization
280F for 2sec
Organic milk
Define: ultra high temp pasteurization
175-302F for 4-15sec
Rare (mexico because dont have good storage)
Sterilize product, can be left out for ~1yr before spoiling
What zoonotic bacterial agents were the targets for setting pasteurization standards?
Coxiella burnetti
Brucella
TB
Why do some people obtain unpasteurized milk?
Tastes different
Claims:
(1) human pathogens are rare on small raw milk farms
(2) helpful in combatting or curing numerous human diseases
(3) more nutrient dense than commercial pasteurized milk
(4) promoting as healthier than pasteurized
How do some people obtain unpasteurized milk?
Small farms: retail sale vs cow shares
Own fraction of cow as investment, government cant say anything about what they do with it
Not allowed in PMO states (but approved for distribution in many states due to recent increased demand)
What risks are being taken by consuming unpasteurized milk?
Not tested as intensely as commercial pasteurized milk
Could have antibiotic residues, high SCC, mastitis, pathogens = DANGEROUS
Many outbreaks traced to raw milk
