milk quality sdl Flashcards
Write down the main health hazards that you can think of from milk and dairy products – what potential pathogens could be ingested?
bovine tuberculosis (Mycobacterium bovis)
campylobacteriosis (Campylobacter spp.)
listeriosis (Listeria spp.)
zoonotic diphtheria (Corynebacterium ulcerans)
What are likely to be consequences of NOT having any form of pre-milking routine?
- Failure to detect clinical mastitis cases – will result in:
o mastitis milk entering the supply (increasing the “Bactoscan”),
o poor cow welfare (missing painful disease),
o poor chance of cure (delayed antibiotic treatment) - Increased bacteria in milk (increased ‘Bactoscan’)
- Increased risk of environmental mastitis infections due to inadequate teat disinfection prior to unit attachment
- Bi-phasic milk let-down and inefficient milk harvesting
- Increased unit on time and development of teat-end hyperkeratosis
What would the sites of contamination from scoring dairy cow cleanliness suggest regarding the likely source of contamination?
(legs, tails, flanks, udders)
Inadequate teat preparation prior to milking
8000
140-150
14 000 million
40%
What is ‘High Temperature Short Time’ (HTST) pasteurisation?
HTST pasteurisation involves heating milk to 71.7°C for 15 seconds, then rapidly cooling it.
It’s based on flash pasteurisation and is commonly used for commercial milk processing
How is the pasteurisation method checked to ensure the correct standard?
The pasteurisation method is checked by testing for alkaline phosphatase (ALP) activity. The pasteurised milk should be ALP negative, as this enzyme is destroyed during the pasteurisation process.
What are the effects of pasteurisation on milk safety and nutrition?
Minimal impact on nutrition — small losses of vitamin C, B12, thiamine
Reduced cream line due to fat globule breakdown
Major benefit: improves microbiological safety
- Removes key pathogens (e.g. Mycobacterium tuberculosis)
- Some concern that MAP (M. avium paratuberculosis) may partially survive, but risk is unclear
What are the key differences in hygiene standards between raw and heat-treated milk, and what are the risks vs benefits of drinking raw milk?
Raw milk:
- Higher risk of zoonotic pathogens (e.g. Salmonella, Listeria, TB)
- Benefits (e.g. taste, asthma protection) are unproven or minor
- Risk is higher in endemic TB areas
Heat-treated milk:
- Risks mainly relate to processing hygiene (e.g. storage, pasteurisation, bottling)
- Pasteurisation significantly improves safety
Fill in the table with problems/actions that may occur during milk processing
How does HTST differ from the ‘holding’ method of pasteurisation?
Holding method: heats milk to 62–66°C for 30 minutes; often used on-farm (e.g. for colostrum).
HTST (High Temperature Short Time): heats milk to ~72°C for 15 seconds; commonly used in commercial dairy processing
