5.1.5 Bacteria in Food Production Flashcards
Microorganisms can be used by humans to produce what?
Foods and other useful substances
As well as fungi (e.g. yeast used to make bread), what is also used in the production of certain foods?
Bacteria
Bacteria are useful because they are capable of producing what?
Complex molecules
e.g. certain bacteria added to milk produce enzymes that turn the milk into yoghurt
They are also useful because they reproduce how?
Rapidly.
the amount of chemicals they can produce can also rapidly increase
Yoghurt is made in a process that relies on the presence of a specific type of bacterium called what?
Lactobacillus
First, all equipment is sterilised to kill other, unwanted bacteria and to prevent what?
chemical contamination
Milk is then pasteurised (heated) to kill other unwanted bacteria at what temperature?
85-95°C
Contamination with other bacteria could slow what?
The production of the yoghurt
(by competing with the Lactobacillus for the lactose in the milk).
It could also spoil the taste of the yoghurt
The milk is then cooled and Lactobacillus bacteria is added at what temperature?
40-45°C
The mixture is incubated at this temperature for how long?
Several hours
while the Lactobacillus bacteria digest milk proteins and ferment (digest) the sugar (i.e. the lactose) in the milk
The Lactobacillus bacteria convert the lactose into lactic acid and what?
This increased acidity sours and thickens the milk to form yoghurt
This lowering of the pH also helps to prevent the growth of other what?
Microorganisms that may be harmful, so acts as a preservative
Lowering the pH means the yoghurt can be kept for a longer time compared to what?
Fresh milk
The yoghurt is then stirred and cooled to 5°C to halt the action of what?
The Lactobacillus bacteria
What may be added before packaging?
Flavourings, colourants and fruit
Fermenters are containers used to grow (‘culture’) microorganisms in large amounts like what?
Bacteria and fungi
Fermenters are used for what 3 products?
Brewing beer
making yoghurt
mycoprotein
What 2 products, not involving food, us this process?
Genetically modified bacteria and moulds that produce antibiotics (e.g. penicillin)
The advantage of using a fermenter is that conditions can be carefully controlled to what?
Produce large quantities of exactly the right type of microorganism
Aseptic precautions is the a condition, how is it controlled?
Fermenter is cleaned by steam to kill microorganisms and prevent chemical contamination, which ensures only the desired microorganisms will grow
Nutrients are the a condition, how is it controlled?
Nutrients are needed for use in respiration to release energy for growth and to ensure the microorganisms are able to reproduce
Optimum temperature is the a condition, how is it controlled?
Temperature is monitored using probes and maintained usin the water jacket to ensure an optimum environment for enzymes to increase enzyme activity (enzymes will denature if the temperature is too high or work too slowly if it is too low)
Optimum pHis the a condition, how is it controlled?
pH inside the fermenter is monitored using a probe to check if it is at the optimum value for the particular microorganism being grown. The pH can be adjusted, if necessary, using acid or alkalis.
Oxygenation is the a condition, how is it controlled?
Oxygen is needed for aerobic respiration to take place
