L25: OPOAO Flashcards
Who performs dairy hygiene inspections?
FSA inspectors
What is wet curing?
Brine injections
What % of salt is used?
1-5%
Above what % salt is shelf-stable?
Over 5%
What microbes do nitrites inhibit?
Spore forming
What is a disadvantage of nitrites?
Form toxic nitrosamines while frying
What other food factors do nitrites affect?
Stabilises pigment, influences flavour
How do phosphates work?
Water retention agents
What is the usual form of phosphates used?
Alkaline polyphosphates
How does lipid oxidation affect microbial growth?
Less lipid oxidation = less microbial growth
How do erythorbic or ascorbic acids affect nitrosamines?
Promote nitric oxide so less nitrosamines
How can corn syrup act as a preservative?
Water binding properties
What is difference between a seasoning and a flavouring?
Seasonings modify flavour, flavourings strengthen specific flavours
What are two examples of meat tenderisers?
Salt and some proteolytic enzymes
What is nicin used for and how does it work?
Bacteriocin used in casings or packaging material
What do antioxidants prevent?
Lipid oxidation
What are some examples of antioxidants?
Citric acid, polyphosphates, EDTA, natural ingredient from rosemary
What is important when using an acidifier?
Timing
What is added to “raw meat fermented sausages”?
Salt, lactic acid bacteria, sugars, nitrite, spices
What temperature are raw meat fermented sausages fermented at?
15-30 degrees
What prevents Salmonella and staph aureus in raw meat fermented sausages?
Salt, fast initial acid, drying, maturing
What prevents Clostridium in raw meat fermented sausages?
Nitrites
What prevents E Coli in raw meat fermented sausages?
High initial temperature and long drying
In which countries is raw cows milk allowed?
UK but not Scotland
What objects are responsible for most of the contamination of raw milk?
Milk handling eqipment
What objects are responsible for most of the zoonoses of raw milk?
Udder (and rodents and foreign bodies)
What is the max milk temperature is daily collection?
8 degrees
What is the max milk temperature if collection is every other day?
6 degrees
What 7 factors is milk tested for?
Protein, butterfat, lactose, SCC, microbial quality, antibiotic residues, water
Which 4 factory determine milk quality?
Protein, butterfat, lactose, SCC
How are antibiotic residues tested for in milk?
ELISA
How is water content tested for in milk?
Freezing point
In raw cows milk, what is the maximum plate count at 30 degrees?
<100,000 per ml
In raw cows milk, what is the maximum somatic cell count at 30 degrees?
<400,000 per ml
If unpasteurised, what must the plate count be below?
<20,000
If unpasteurised, what must the coliform count be below?
<100
In raw other species milk, what is the maximum plate count at 30 degrees?
<1,500,000 per ml
If processed without heat (some cheeses), what must the plate count be below?
<500,000 per ml
What do milk buyers use as a measure of quantity?
Bactoscans
What amount of water and temperature do you need when cleaning a milking unit?
10-15L per milking unit at 85 degrees at the start and no less than 50 degrees at the end
What amount of water and temperature do you need when cleaning a milking unit with acidified boiling water?
14-18L per unit starting at 96 degrees and all parts of equipment must reach 77 degrees for at least 2 minutes
What temperature and time is pasteurisation?
72 degrees for 15 seconds
Which two tests must milk have following pasteurisation?
Microbiological assessment and phosphatase test
What temperature must milk be for chilled storage?
Less than 6 degrees
How can you modify curd when making cheese?
Heat, pressure, ripening ferments, special moulds, seasoning
What are the three types of cheese?
Hard, semi-hard, soft
Which kind of cheese can be with or without gas holes?
Very hard
What are two ways of ripening semihard cheese?
Moulds (Roquefort) or bacteria (Brick)
What are two ways of ripening soft cheese?
Bacteria (limburger), mould (camembert) or unripened (cottage)
How soon must milk be treated or processed if refrigerated below 6 degrees?
36 hours
How soon must milk be treated or processed if refrigerated below 4 degrees?
48 hours
How soon must buffalo, ewe or goats milk be treated or processed?
72 hours
What does thermisation do?
Improves the keeping quality before processing, but does not destroy pathogens
What temperature and time for thermisation?
57-68 for 15 seconds
What must starting cfu/ml be for thermisation to work?
100,000 cfu/ml
What do you not need to do when making soft cheese?
Heat
What happens during curd preparation to make soft cheese?
Add blue moulds e.g. penicillium
How are curds ripened?
Salted or brined
What temperature, humidity and time are curds ripened for?
10 degrees and 95 humidity for 60 days
Which test ensures effective pasteurisation?
Phosphatase test
Why must you rotate stock and check acid development in cheese?
Slow acid development may result in bacterial proliferation
What is one problem that can happen during ripening?
Overgrowth of contaminants
What are three common cheese contaminants?
Salmonella, Listeria, Staph enterotoxins
What does rennin do?
Coagulates the casein of milk and forms an insoluble calicum complex
How can you harvest rennin?
Blumenthal process, HCl process, Keil process
Why are enzyme combinations used with rennet?
Low proteolytic activity
How much of milk is made into cream and butter?
1/3
What % salt is added to cheese?
10-13%
What are three ways salt improves keeping quality of cheese?
Reduces microbial growth, inhibits yeast and mould, inhibits proteolytic and lipolytic organisms
How do you disinfect fruit before opening?
Dip in 336ppm chlorine for 2 mins before opening
What diameter filter do you use for butter?
0.1mm
Above what concentration lactic acid do caseins coagulate?
Over 1g/100ml
How does cooling affect fermentation?
Halts
From which pH is the base stirred?
4.6
What is the ideal pH of a fermentation starter culture?
4.2-4.3
How long does fermentation take to form a bio-product?
4-5 hours
How long does fermentation take to form a mesophilic product?
12-16 hours
What does the flavour of butter come from?
Milk components esp fat and products of certain bacteria eg Strep lactis
How can emulsion of water in fat allow bacterial growth?
Low moisture should prevent, but if emulsified there is still sufficient water and soluble food so growth can occur between the fat globules
