Food Spoilage And Preservation Flashcards
How can you tell that food is off?
The food has developed off flavours and smells.
There has been a change in appearance.
How does food spoil?
Natural decay within the food
Contamination by microorganisms
Foods that spoil quickly-perishable
Milk, meat, soft fruits, poultry, cream, eggs, seafood, soups
What do perishable foods contain a lot of?
Water and nutrients
What about processed versions?
They have been designed to be preserved but they must be eaten or stored as soon as they are open as they once again become perishable.
What does the use by date mean?
This is the date by which the food should be eaten to ensure that it is safe.
What does the display until sign mean?
The food must either be sold by then but it still safe to eat 2-3 days after.
What does the best before date mean?
This is usually for non perishable foods. It means that they will be in best condition before this but can still be eaten after but they may taste weird.
Two ways that natural decay happens.
Moisture Loss and the action of enzymes
What is moisture loss?
This happens in fruits and vegetables as after they are harvested, they continue to respire. This means that water comes out through their leaves and skin.
What is the action of enzymes?
Enzymes are proteins and they’re destroyed by heat or acids. Once they are activated, they start to break down the tissues and parts of a food. But they also cause fruits to ripen.
What three microorganisms cause food decay?
Yeast, mould and bacteria
How to microorganisms make food unfit to eat?
They either produce waste toxins or make it inedible by just being there
Where is bacteria found?
Air, water, sewage, soil, dust, plants, animals, people
What do bacteria need to multiply
A suitable temperature
Moisture
A food supply
What temperate are most bacteria killed at?
60°
Bacteria produce very quickly at…
20-50°C
Bacteria become dormant at…
10°C or lower
What temperature should a fridge be kept at?
1-4
What do mould need to reproduce?
A suitable temperature (often warm to 37°C)
Moisture
A food supply
How do mounds reproduce?
Send out tiny air-borne spores that land on food and grow if conditions are right.
What are yeasts?
Yeasts are tiny celled fungi that are found in air, soil and on the surface of fruits.
What do yeasts need to grow?
They reproduce by budding( send out a little bud that grows into a yeast cell). They need water, warmth and food.
When are yeasts dormant and when are they killed?
They are dormant in cold conditions and killed at 100°C.
