U2 B5 2HVTTO

• Biologie
• Middelbare school
• havo, vwo
• Leerjaar 2

B5 Food spoilage

Lessongoals

• You can describe ways to prevent food spoilage

Clara is an adult woman. She calculates her BMI.
How should she do that?

1. BMI=​weight​2​​​​length​​
2. BMI=​lenght​2​​​​weight​​
3. BMI=​weight​​length2​​
4. BMI=​length​​weight​2​​​​

When she calculates her BMI it is 23,5. What does this mean for her?

1. Her weight is too low
2. Her weight is healthy
3. Her weight is too high
4. Her weight is way too high

A certain foodstuff contains 20 kJ of energy. How much J is that?

1. 2.000 J
2. 20.000 J
3. 0,002 J
4. 0,02 J

Mirre and Jara are twins. The amount of energy they need is not the same.
What is the most logical reason for this difference?

1. Their sex is different
2. Their body length is different
3. Their age is different
4. Their physical activity is different

Why does food spoil?

What happens when you eat/drink spoiled food?

Food spoilage

Bacteria and fungi eat our food = food spoilage

They need:

• Food
• Moisture
• Right temperature
• Right environment

Preserving food is done by changing these things. making it impossible/hard to live on the food for bacteria/fungi

Preserving - Water

• Drying

             Bacteria/fungi dry out

Preserving - Cooling

• Fridge > 3 - 4 °C

            Bacteria/fungi are slowed

• Deep freeze > -20 °C

            Bacteria/fungi are frozen

Preserving - heating

• Pasteurization > 72 °C

           Most bacteria/fungi are killed

• Sterilization >130 - 140 °C

            Bacteria/fungi are killed

Preserving - Additives

• Preservatives 

           Sugar                   Acid

           Salt                       Sulphite

           Vinegar

• Additives

            Colourings       Aromas

            Flavourings

Preserving - other ways

• Irradiation

             Bacteria/fungi are killed with radioactive rays

• Inert packing

             Adding a mixture of gases to the packaging helps the food stay fresh                 longer

• Vacuum packing

            After pasteurization/sterilization/preservatives/inert packing

           Bacteria/fungi are unable to reach the food

What you should do:

• Read pages  125-127
• Do asgmt  1-8, 4c pgs. 128-131

Done with the above?

• Work on the next chapter(s)
• Learn for the test 
• Make other homework
• Read a book

Zs = Working in Silence

• No asking questions
• Silent, don't disturb anyone
  
• Stay at your  desk

What you should do:

• Read pages 125-127
  
• Do asgmt 1-8, 4c pgs. 128-131

Done with the above?

• Work on the next chapter(s)
• Learn for the test 
• Make other homework
• Read a book

Zw = Working with whispering

• Teacher is available for questions
• Only whisper with the student next to you
• Stay at your  desk

Tidy Duty

Today these people are on tidy duty

• Desks: empty and straight
• Chairs:  underneath the desks
• Floor: no rubbish