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
Cream definition
Oil in water emulsion
Production of cream
- Milk is heated to 50°C
- Upper cream layer is then separated from the lower layer of skimmed milk by centrifugal force
- The cream is heat-treated using pasteurisation, sterilisation or UHT
- Cream is sealed into cartons and labelled
Type, BBD, storage
Types of cream
Double cream
Whipping cream
Single cream
Cooking cream
Sour cream
What is buttermilk
A by product of butter production, it’s an acidic liquid used in bread making and baking
Production of yogurt
- Whole, low fat or skimmed milk is homogenised
- It’s pasteurised at 90°C to kill bacteria then cooled to 37°C
- A culture called lactobacillus Bulgarians is added, which is then incubated (37°C) for 6-8 hours to allow FERMENTATION to occur. Lactose changes to lactic acidosis and milk proteins coagulates. This thickens the yogurt
- Yogurt is cooked and other ingredients such as flavours, colourings, fruit and nuts are added to it
- The yogurt is packaged for sale in sealed cartons or jars
Labelled with type, BBD, ingredients and storage
Fermentation
Process by which micro organisms convert sugar to acid or alcohol
Types of yogurt
Full fat
Yogurt drinks
Frozen yogurt
Bio- Yogurt
Bio yogurts
Contain additional bacteria such as lactobacillus casei which may help support the natural bacteria in the intestine and help regulate digestion
A functional food
Hard cheese
Cheddar
Parmesan
Semi hard cheese
Gouda
Soft cheese
Brie
Cottage
Processed cheese
Cheese slices
Cheese spreads
Cheese strings
Cultured cheese
Extra mould or cultures added to change appearance or flavour
Blue cheese
Mould added
Blue veins
Smell
Flavour
Cheese with external mould
Powdery white mould on outside
Creamy texture
Brie
Cheese with holes
Starter culture produces CO2 during fermentation and while cheese is maturing
Forms holes
Swiss cheese
Irish farmhouse cheeses
Speciality foods.
Produced in small quantities using locally sourced ingredients and artisan skills
Growing sector in the dairy market
Production of cheese (ADDED VALUE FOOD)
- Culture of lactic acid bacteria is added to pasteurised milk. Changes lactose to lactic acid.
- Milk is heated to 30°C and rennet is added. Rennet contains the enzyme rennin which coagulates milk protein.
- After 30-45 mins the mixture has separated into curds and whey
- Curds are chopped, releasing more whey, which is drained off (cottage cheese here)
5,6,7,8,9
Packaged and labelled
How much milk to make cheese
1L for 100g of cheese
Cheese
Protein
HBV
27%
Casein
Growth and repair
Cheese
Fat
Saturated
Hard- high
Skimmed milk - 33% fat
Heat and energy, protection of organs
Cheese
Carbohydrate
Lacks
Lactose is converted to lactic acid
Heat and energy
Serve with carbs
Cheese
Vitamins
A (rhodopsin)
b (metabolism
Some D
Lacks c
Cheese
Minerals
Calcium - bones and teeth
Salt and sodium
Cheese
Cost
As there is no waste and no cooking necessary, cheese is a relatively inexpensive but concentrated source of nutrients for all age groups
It’s a value added food meaning that it’s more expensive
It’s nutrient dense making it worth the money
Can be eaten/ used without further cooking, reducing energy costs in the home
Cheese
Versatile
Cheese is available in a wide range of flavours and textures, making it a versatile food that can be eaten on its own or used as an ingredient in sweet or savoury dishes
Sweet dishes include: cheese cakes
Savoury dishes include: pizza or brie as a starter meal in a restaurant
Cheese
Available
Individuals on low fat or low cholesterol diet should limit their intake of full fat cheese as it’s high in kilocalories and saturated fat
A range of low fat cheeses are available to suit the needs and wants of the consumer.
Effects of cooking on cheese
Protein coagulates
Fat melts
Colour change brown
Overcooked becomes tough and indigestible, fat delegates and cheese becomes stringy
Processed cheeses
Cheese product made from chopped ripened cheese with added salt, water, whey powder, dried milk and emulsifiers
Colourings and flavourings are added
Packed into blocks slices or strings
Nutritive value decreased due to water
Milder taste— children
Milk
Protein
HBV
caseinogen lactalbumin lactoglobulin
3.5%
Growth and repair
Milk
Fat
Saturated
Present in the form of tiny droplets
Easy to digest
Fat content varies according to type of milk eg: whole milk : 4%
Heat and energy
Milk
Carbohydrate
Lactose, disaccharide
Lacks starch and cellulose
4.5% average
Heat and energy
Milk
Vitamins
A (eyes)
D (bones and teeth)
B2
Niacin
Thiamine (destroyed in heat treatment)
C lost in processing
Minerals
Calcium (bones and teeth)
Phosphorus
Traces of potassium and magnesium
Lacks iron
Milk
Cost
Milk is relatively cheap, available in a variety of types and supplies a wide range of nutrients in an easily digested form
Versatile food with many culinary uses
Milk
Available
Wide range of types, including whole milk, low fat and lactose free to suit individual diets
Fortified milks have extra nutrients added
Milk
Versatile
Culinary uses of milk
Milk is fortified with
A D B (folic acid and B12)
CALCIUM PROTEIN OMEGA FATTY ACIDS
