Please enable JavaScript.
Coggle requires JavaScript to display documents.
Microorganism Design Practical - Coggle Diagram
Microorganism Design Practical
Highly perishable foods susceptible to bacterial growth
Reference: Perishable Foods | List of High Impact Articles | PPts | Journals | Videos (2021). Available at:
https://www.imedpub.com/scholarly/perishable-foods-journals-articles-ppts-list.php#:~:text=Perishable%20foods%20are%20those%20likely,products%2C%20and%20all%20cooked%20leftovers
. (Accessed: 22 April 2021).
Raw and Cooked Red Meat
Raw and Cooked Poultry + Eggs
Dairy - milk, cheese, yoghurt
Cooked rice and pasta
Soy products e.g Tofu
Any of these foods can be tested for microbial growth
Favourable conditions for microbial growth
Time
Providing time for the bacteria to grow will increase their numbers within a food, given the growth conditions allow them to do so.
Cooking time
Foods such as meats must be properly cooked for a specific time in order to kill any existing microbial presence and ensure it is edible
Cooking time can be tested against bacterial growth. However, it may contribute to a large quantity of wasted food if a sizeable sample is needed for each trial. As such, it may not be viable for the practical.
Temperature
The temperature range between 5c and 60c is known as the danger zone which is the ideal temperature for bacteria to grow. Reference: Perishable Foods | List of High Impact Articles | PPts | Journals | Videos (2021). Available at:
https://www.imedpub.com/scholarly/perishable-foods-journals-articles-ppts-list.php#:~:text=Perishable%20foods%20are%20those%20likely,products%2C%20and%20all%20cooked%20leftovers
. (Accessed: 22 April 2021).
Various ways of testing the effect of temperature can be implemented such as cooking temperature, incubation temperature as well as time left at a certain temperature
Sodium Content/Moisture
Salt draws out water from food through osmosis, therefore removing the moisture that bacteria and other microbes favour for growth. Reference: How Does Salt Preserve Food? (2021). Available at:
https://www.thoughtco.com/why-does-salt-work-as-preservative-607428
(Accessed: 22 April 2021).
Nutrient Availability
Bacterial growth is increased when more nutrients are present as this will serve as a source for bacterial fermentation, allowing them to reproduce
Sanitation and Storage
Storage temperature - below 5c or above 60c
Can be tested against bacterial growth (as an IV)
Equipment sanitation and contamination
Cutting board sanitation?
Knife sanitation?
Cross contamination of high risk foods can be tested using foods that can easily encourage microbial growth (meat)
Possible Dependent Variables
Surface Area occupied by bacteria (cm2) - measured with a ruler (length and width)
Number of bacterial colonies Reference: Measuring bacterial growth (2021). Available at:
http://loretocollegebiology.weebly.com/measuring-bacterial-growth.html
(Accessed: 21 April 2021).
This variable may be difficult to calculate if there is significant growth on the agar plate/food item
Possible Independent Variables
Temperature - a range within the danger zone (20,40,60)
Sodium Concentration (%) or Sodium Quantity (mg)
Salt + Water solution with various concentrations of salt
Can be used to test raw/deli meat to simulate the preservation process that is meant to prevent bacterial growth (curing) Reference: Curing and Smoking Meats for Home Food Preservation (2021). Available at:
https://nchfp.uga.edu/publications/nchfp/lit_rev/cure_smoke_cure.html
(Accessed: 22 April 2021).
Salt can be directly applied and measured beforehand
Storage Time (hours)
may be difficult to record each trial after the set time has elapsed