Veterinary roles with other products of animal origin (OPOAO) Flashcards
Meat technology: what can be added to meat and why?
Salt sodium chloride: preservation, flavour etc.
Nitrite: inhibiting spore forming bacteria, may be toxic
Nitrate: less used in long drying products
Phosphate: mainly water retention
Erythorbic or ascorbic acids: promotes nitric oxide
seasonings
flavourings
tenderisers
antimicrobials: nicin
antioxidants: preventing lipid oxidation
acidifiers
soy protein, milk ingredients, starch ingredients, gums and hydrocolloids, animal derived extenders
Zoonotic diseases of milk and milk products
○ Brucellosis
○ Salmonellosis
○ E. Coli O157:H7
○ Campylobacter
○ Staphylococcus
○ Q-fever
○ Leptospirosis
○ Listeria
○ Yersinia
○ Mycobacterium bovis
○ (M. Avium paratuberculosis)
Milk borne chemical contaminants
○ Antibiotics
○ Mycotoxins
○ Heavy metals
○ Radionucleotides
○ Disinfectants
○ Contaminated water
○ Pesticides
Criteria for raw cows milk
Plate count (at 30 degrees) per ml <100,000
Somatic cell count per ml <400,000
If milk for sale unpasteurised (not allowed in Scotland)
§ Plate count (at 30 degrees) per ml <20,000
§ Coliform count per ml <100 coliforms
Criteria for raw cows milk
Plate count (at 30 degrees) per ml <100,000
Somatic cell count per ml <400,000
If milk for sale unpasteurised (not allowed in Scotland)
§ Plate count (at 30 degrees) per ml <20,000
§ Coliform count per ml <100 coliforms
Criteria for raw milk of other species
Plate count (at 30 degrees) per ml <1,500,000
Milk from other species processed not requiring heat treatment (certain cheeses)
§ Plate count (at 30 degrees) per ml <500,000
Milk buyers tend to use Bactosans as an ongoing measure of milk quality
Circulating cleaning of milking machine
§ 10-15 litres per milking unit
§ 85 degrees at start
§ Not less than 50 degrees at end
Acidified boiling water cleaning of milking machine
§ 14-18 litres per unit
§ Start at 96 degrees
§ All parts of equipment to reach 77 degrees for at least 2 minutes
Pasteurisation
□ 72 degrees for 15 seconds
□ Laboratory assessment
® Microbiological assessment
® Phosphatase test
Reception of raw milk
○ Unrefrigerated
§ Treat or process as soon as possible after arrival
○ Refrigerated at <6 degrees
§ Treat or process within 36hrs
○ Refrigerated at <4 degrees
§ Treat or process within 48hrs
○ Buffalos, ewes, or goats milk
§ Treat or process within 72 hrs
Thermisation
○ Improves keeping quality pending processing
○ Does not destroy pathogens
○ 57-68 degrees for 15 seconds
§ Not to be used to ‘improve’ spoiled milk - starting level must be <300,000 cfu/ml, 100,000 if for drinking milk
Hard cheese manufacture
§ Milk + lactic acid bacteria
§ Rennet added - semisolid mass
§ Curd cut, stirred and heated
§ Whey drained off
§ Curds shaped into wheels
§ Wheels cured
Manufacture of semi-hard cheese
§ Similar to hard
§ Not necessarily cut or heated
Manufacture of soft cheese
§ Similar to hard
§ Heating unlikely
§ Curing usually starts on the surface
§ Cures inwards to the centre
§ Blue moulds added during preparation of curd
□ Penicillium roquefortii
□ Penicillium glaucum
§ Curds salted or brined for ripening
§ Ripened at 10 degrees 95% RH for 60 days
Rennet
Enzyme - rennin
§ Coagulates the casein of milk
§ Forms an insoluble calcium complex
3 methods of harvest
§ Blumenthal process
§ Hydrochloric acid process
§ Keil process
Rennet production
§ Ground calf stomach is acidified
§ Agitated slowly for 24hrs or more
§ The mucin forms a curd on the top
§ This curd is dried and powdered for use, then diluted
