Yoghurt and MycoproteinUsing microorganisms in food production

21/01/2015

Year 10 Biology

How do we make yoghurt?• Microbes are used in production of

some foods.• Milk can be turned into yoghurt with

the help of a certain kind of bacteria• Milk is Pasteurised (heated to kill

all bacteria it contains, then cooled)• Lactobacillus bacteria is added to

milk at an optimum temperature - 40ºC

• The bacteria respire anaerobically (without the presence of oxygen)

• They convert Lactose into lactic acid, lowering the pH of the milk.

• The low pH coagulates milk (makes it turn solid) converting it into yoghurt.

Yoghurt demo.• What happened?  When you put the yogurt

“culture” into the milk, you released living bacteria into the milk, and they were in “bacteria heaven”—they feasted on the natural sugar in milk, called “lactose.”  As a result of their digestion, bacteria then released lactic acid, which is what makes yogurt slightly sour.  Then the proteins in the milk clumped together to thicken the mix.  Temperature was very important in all of this—if it had gotten too hot, the bacteria would have died.  So in case there’s any doubt—there really is stuff inside yogurt that is alive!

Mycoprotein• Fungus can also be used to make

some foods. • Quorn is a meat-substitute that

provides protein for vegetarians.• The fungus (called fusarium) is

put in a fermenter at 30ºC.• It is given glucose (for energy)

and ammonia (a source of nitrogen)

• The fungus grows hyphae (a long structure made up of protein).

• This protein is then processed and flavouring/colourings are added.

• The protein is then used to make veggie-burgers or sausages.

https://www.youtube.com/watch?v=scO2ZZKFjMk

https://www.youtube.com/watch?v=ZEFa2BvNYmI

http://www.bbc.co.uk/schools/gcsebitesize/science/triple_aqa/humans_and_environment/food_production/revision/2/

Food Additives

• Chemicals are added to food before we buy it. These are food additives.

• Flavourings are used to enhance the taste of foods. MSG (monosodium glutamate) is a common flavouring.

• Colourings are chemicals that add attractive colours to processed foods to make them look more attractive.

• Anti-oxidants/preservatives are added so food doesn’t decompose or oxidise.

• Emulsifiers are additives that allow oils and fats to mix with water.

Additives and E-numbers

• Numbers are used to label and identify the additives found in foods.

• The numbers are the same throughout the world - in Europe they have a letter E in front (they are called E numbers.)

• Numbers 100-181 are all colourings.• Numbers 200-290 are preservatives.• Numbers 300 - 385 are antioxidants• Numbers 400-495 are emuslifiers• Numbers 620-640 are flavourings (MSG

is E621)• Some food additives are natural

(extracted from organisms) • Some are artificial (not found in

organisms)

Free from artificial colourings and flavourings

Free from additives?

anthocyanin glycosides

Beta carotene

Are food additives safe?

• Tartrazine (E102) is a yellow colouring used in jam, drinks and many snacks. It has been linked to problems like asthma/hyperactivity, especially in children.

• E102 is banned in some countries (e.g. Norway) and some people want it to be banned in the UK.

• E954 is a chemical called saccharin ( a substance that sweetens food) It was banned in the USA in 1970s but has now been shown to be safe for humans.

What’s the problem with additives?Aspartame (E951)

tryptophan

Violent aggressive behaviour ?

Tartrazine (E102)

Asthma, hyperactivity?

Sunset yellow (E110)

Kidney damage

Under the subheading microorganisms in food.Write a few lines stating the name of the microorganism used and bullet point the method for each of the following:1. Baking, 2. Brewing, 3. Yoghurt making,4. single-cell protein (scp),5. mycoprotein.

Under the subtitle additivesState: a. its function in processed foodb. One advantage of its usec. One disadvantage of its use.

6. Preservatives7. Flavourings8. Colourings9. AntioxidantsQuestions on age 51 and 53.

Sources of nutrients 11/01/2015

Starter glue in and examplain what the

food pyramid represents.