Multi-components of food

Question 1

Types of Extruders

Answer 1

Cold

Cooking

Question 2

Foods made using extruders

Answer 2

Sausages
Pasta
Breakfast cereals

Question 3

What is and extruder

Answer 3

Process used to create long objects
Food pushed through a die (plate) that is shaped with the desire cross sectional shape

Can create hollow sections by placing a pin or mandrel in middle

Question 4

Cold extruders

Answer 4

Temperature of food remains ambient
Pasta and meat
Shape and size depends on shape or die
Product is dense and still raw

Question 5

Extrusion Cooking

Answer 5

Dough temperature exceeds 100 degrees
High pressure prevents steam formation during mixing
On leaving die food expands rapidly releasing pressure
Used for snack and breakfast cereals

Question 6

Puffing

Answer 6

Partially dried food with moderate moisture content is sealed in pressure chamber

Chamber temperature is increased to above 100 degrees and pressure released
Rapid loss of pressure causes food to expand
Allows fast drying and rehydration

Question 7

Water mitigation

Answer 7

Water content - how many g water present
Water activity - How much water is not strongly bound to other molecules

Texture and physical propertied determined by water activity not water %

Question 8

Osmosis in food

Answer 8

If Aw and water content increase - solid food becomes moist and soggy and increase risk of microbial growth

If Aw and water content decrease - gel shrinks and cracks, solid food becomes dry and hard, turgid food looses crispiness

Question 9

Prevention of water migration

Answer 9

Minimise contact time
Choose ingredients with same Aw
Physical barriers

Question 10

Example of physical barriers to prevent Osmosis

Answer 10

Layer or coating of edible fat

Plastic packaging

Question 11

Microbial Risk

Answer 11

Contamination sources in ingredients
Changes in growth conditions
Ensuring safety of multi-component foods

Question 12

Contamination sources in ingredients

Answer 12

Some ingredients cannot be pasteurised

Can introduce pathogens and spoilage microbes, which cannot grow in those ingredients

Question 13

Changes in growth conditions

Answer 13

Increase in Aw due to water migration can allow otherwise dormant spores to germinate and grow
Difference in pH or other constituents can allow organisms to grow where previously sterilised ingredients

Question 14

Ensuring safety of multi-component foods

Answer 14

Strict food handling
Raw components prepared fresh
Keep at 63 degrees till served
Careful planning of ingredients