2.5 food spoilage

• Biologie
• Middelbare school
• vwo
• Leerjaar 2

Today's lesson

recap 

• Food poisoining
• Preserving food
• Additives

selfstudy 

Which organ produces bile to aid in digestion?

1. Liver
2. Pancreas
3. Gallbladder
4. Stomach

Chewing your food is part of
.... digestion

1. Mechanical
2. Motor
3. Chemical
4. Chew

Meyra en Miray 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

Look at the pictures. What is the most important nutrient in these foods? Choose one word for each picture.

additive

calorie

nutrient

minerals

carbohydrates

fat

protein

vitamins

salt

sugar

Food conservation

What causes your food to spoil?

Micro organisms (molds and bacteria)

The decomposers break down natural waste (chapter 6). 

They secrete toxins (which are harmfull to humans)

Food poisoning

Food spoilage (voedselbederf) = when unwanted fungi or bacteria grow on your food. 

Food poisoning (voedselvergiftiging) = When you fall ill by toxic substances in your 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

Fungi (or moulds)

They contain thin threads with which they suck up food. 

They also contain small balls, containing spores.  A new fungus can grow from each spore.

Bacteria

Replicate by cell division (celdeling)

Replication speed depends on the conditions:

- temperature

- moisture

How do you prevent food spoilage?

Preserving (conserveren)= keeping food fresh for a longer period of time

1. Heating 
2. Cooling and freezing 
3. Adding substances (stoffen toevoegen)
4. Vacuüm or special gas packaging
5. Drying

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

Which statement is false?

1. Food spoilage is caused by fungi and bacteria.
2. Fungi cannot be seen with the naked eye, bacteria can.
3. Food can be infected by other people and animals.
4. Food spoilage can cause diarrhoea.

off to work 

2.5 food spoilage

do ex. 3/5/6/7/8

learn the digesitve system, organs and function