Milk and Dairy Products Flashcards
Homogenisation
Milk is heated to 60°C forced under pressure through tiny valves.
This breaks up the fat globules into smaller fat droplets which are distributed evenly throughout the milk
Effect of homogenisation
Smaller fat droplets remain evenly distributed in the milk forming a layer of cream
Milk is creamier, better flavour
Pasteurisation
Heated to 72° for 15-25 seconds
Cooled to 10°
Sterilisation
Homogenised
Sealed into bottles
Heated to 110°C
For 30 mins
Cooled
UHT
132°C for 1-3 seconds
Poured over a heated surface
Cooled
Sealed into sterile containers
Evaporated milk
Pasteurised
Evaporated to half its volume
Homogenised
Sealed into tins
Sterilised at 115°C for 20 mins
Heat treatments list
Pasteurisation
Sterilisation
UHT
Evaporated milk
Effects of heat treatments
Loss of C and B
All pathogenic bacteria/ microorganisms are destroyed
Extends the shelf life
Ways to Dried/Dehydrated milk
Roller drying
Spray drying
Roller drying
Milk is poured over revolving rollers and is scraped off as it dries
Milk powder is cooled and packed into airtight containers
Effect of roller drying
Destroys amino acids and B
Bacteria destroyed
Flavour altered
Spray drying
Milk is sprayed into a hot air chamber.
The droplets dry to a fine powder as they fall.
Cooled and packed into airtight containers.
Effects of spray drying
Loss of amino acid and B
Bacteria are destroyed
Better flavour than roller-dried milk and reconstitutes more easily
Buying and storing milk
Check it’s stored correctly in shop
Date stamp
Use milk in rotation
Never mix milks with different dates
Refrigerate asap
Keep covered and away from smelling foods
Effects of cooking on milk
Protein coagulates, forming a skin on the surface of the milk
Bacteria are destroyed
B lost
Flavour altered due to caramelisation of lactose
Spoilage of milk
Occurs when lactic acid bacteria break down the lactose in milk to form lactic acid
Unpleasant taste
Curdles
Curdling
Occurs when caseinogen separates from the liquid part of the milk
May occur due to:
Addition of an acid (lemon juice)
Heat
Addition of enzymes (rennet: cheese making)
Milk quality
Enforced by Department of Agriculture, Food and the Marine
- Cattle are routinely tested for TB
- All farms are subject to inspections
- Strict codes of hygiene when transporting storing and processing milk
- Milk is sampled and tested for microbial contamination and the presence of antibiotic residues
- Milk is heat treated to destroy bacteria, making it safe for human consumption and to increase its shelf life
Disease- causing organisms found in unpasteurised milk
Salmonella
Ecoli
Listeria
Restricted sale in ireland
Butter definition
A water in oil emulsion made from pasteurised cream
Butter production
- Cream is pasteurised then chilled
- It’s churned until the fat particles clump together into granules seperating from the buttermilk, which is drained off
- Salt is added and the butter is worked to distribute the salt
- It is weighed and packaged in foil, grease proof wrapping or in plastic containers
Labelling includes: type of butter, BBD, storage, ingredients and nutritional indo
Types of butter
Butter
Unsalted
Spreadable
Reduced-Fat
What temp does butter decompose
Low temp (unsuitable for frying)
Storage of butter
To prevent oxidative rancidity store in fridge wrapped
Remove shortly before use