Unit 3 Summary
Unit 3 took a look at the factors that affect microbial growth
o how microbes reproduce
o Intrinsic and extrinsic factors that affect microbial growth
o The importance of microbial ecology in foods
o Importance of microbial ecology in foods
o Growth prediction models in food microbiology
• Bacteria grows by binary fission and thus grows at an exponential rate, each new
generation doubling the size of the previous
• Intrinsic factors are factors such as nutrients, growth factors, water activity, pH, redox
potential and inhibitors (antimicrobials)
• Extrinsic factors include temperature, relative humidity, gaseous environment content
and the presence and activity of microorganisms
• Models can be used that predict growth of bacteria by factoring how different intrinsic
and extrinsic factors affect microbial growth of different types of organisms of different
values of each affecting variable
Unit 4 Summary
Unit 4 discusses food spoilage of meats, poultry, vegetables, fruits and milk.
For all categories timing, environment and types of bacteria are important. Meats and milk are
nutrient rich containing protein, vitamins and minerals needed to sustain us and microorganisms.
The unit talks about the types of microganisms that can grow in certain foods and the type of
food spoilage that will occur. When going through the unit it is important to relate the nature of
the spoilage to the characteristics (ie growth parameters and metabolic products) of the microbe.
Unit 6 Summary
Foodborne illness is an important aspect of food microbiology and is important for the food
industry. Knowledge about its characteristics can be useful in helping control pathogens to
desired levels in which they are unable to cause illness.
Foodborne disease can be caused by different pathogens, usually ones that survive refrigeration,
heat and other conditions, growing in food and food ingredients.
Three categories of disease are: (1) Intoxication, caused by pathogenic bacteria that produce toxins; depending on the
bacterium, can cause enteric or neurological symptoms or cancer. (E.g. Mycotoxicosis ,
Staphylococcus, Clostridium botulinum).
(2) Infection, caused by enteric pathogenic bacteria and viruses. The viable cells survive the
environment of the GI tract and target infection in the intestine producing enteric
symptoms and fever, and possibly death. (E.g. Salmonella, E.coli, Listeria, Yersinia).
(3) Toxicoinfection, caused by sporeforming cells. When contaminated food are consumed,
they spolurate in the GI tract and release the toxin, produce enteric symptoms and require
high number of cells to cause disease. (E.g. Clostridium perfringens, Bacillus cereus, Vib.
To prevent and reduce foodborne diseases, proper food safety practices including sanitation
should be practiced. It is important to conduct training among the employees, including
managers and supervisors to ensure a safe final product. Important to note is the identification of
critical control points (CCPs) and the use of HACCP (Hazard Analysis and Critical Control
Point) which help reduce the risk of contamination of foods and food products throughout the
whole processing and preparation of the food.
In the event of an outbreak, proper investigation must be done in order to determine the possible
source of infection, and stop the spread. A few things can help with the investigation, such as
knowing the symptoms and the incubation period, to identify the pathogen and take the
The 6 steps are as follows: detect outbreak, generate hypothesis, design epidemiology study to
test hypothesis, analyze and interpretate the data, execute other studies, and implement control
and prevention measures.
In conclusion, it is imperative to know how to recognize what symptoms each pathogen causes,
what their incubation period is, and which foods and conditions they likely grow in; in order to
be able to identify pathogens that are causing illnesses in humans. Implementing good food
safety practices, sanitation and training food handlers, servers, managers and supervisor can help
reduce the risk of contamination and ultimately lower risk and prevalence of foodborne illness.
Unit 7 Summary
The Enumeration and Rapid Detection Techniques unit introduced aseptic techni