1. Why does drying food help preserve it? Why does keeping food cold help
2. Give an example of a fermented food. Name the starting “material” and the
fermented product. (e.g., milk can be fermented to produce yogurt)
3. What is the difference between fermentation and spoilage?
4. Describe some benefits of the following advances in technology with respect
to food microbiology:
a. Development of the microscope
c. The Gram stain
d. Development of Koch’s postulates
e. Development of aseptic technique and pure culture
5. What is the microbiome?
6. What is a foodborne pathogen (what does the term mean?)
7. We discussed classification of organisms into kingdoms: plants, animals,
protists (algae and protozoans), fungi, eubacteria, and archaea. Be able to
compare and contrast as follows:
a. Which are prokaryotes and which are eukaryotes?
b. Name two differences between [prokaryotes and eukaryotes.
c. To which group do helminths belong? (What is a helminth?)
d. To which group do yeasts and molds belong?
e. Comparing eubacteria and archaea, which type can cause disease in
f. Comparing protozoans and animals, which are always single-celled
g. F of the above categories of organisms, which are found in “extreme”
environments (bottom of the ocean, hot springs, etc.)?
h. We also talked about viruses, which are not considered alive. Why did
we say that viruses are not alive (what characteristic of living things
do they lack?)
i. What sorts of cells do viruses infect?
j. Can viruses cause disease? Can they be foodborne pathogens?
8. Give examples of intrinsic and extrinsic factors that affect growth of microbes
9. What do we mean by water activity (aw)? Be able to recognize aw levels of
different foods and identify which has the higher aw. Which type of food
(with lower or higher aw) would be more likely to harbor a food pathogen?
10. What number is associated with neutral pH? If a food has pH5, is it acidic or
basic? If it is pH8, is it acidic or basic? Which type of organism is more likely
to grow at acidic pH: molds, or bacteria? Why do microorganisms tend to
produce an acidic environment when they are metabolically active?
11. What do we mean by VNC (viable but nonculturable)? Would the presence of
such microbes cause us to overestimate or underestimate the number of
microbes in food?
12. 12. Regarding temperature: what is the “danger zone” in which microbes can
grow if food is held at that temperature?
13. Does refrigeration kill microbes?
14. Does boiling kill microbes?
15. Compare and contrast aerobes and anaerobes:
a. Which require oxygen for growth, and which are killed by oxygen?
b. Are humans aerobes or anaerobes (indicate which)?
16. Name two metabolic products that are produced by fermenters.
17. Of aerobes, anaerobes, and fermenters, which can grow in food?
18. Which can cause food spoilage?
19. Which can cause foodborne illness?
20. Compare bacterial endospores and fungal spores:
a. Which are considered reproductive structures?
b. Which look like “cottony,” fluffy structures when grown in the
laboratory (or on food)?
c. Of the two, which are more resistant to heat and dryness?
d. Which can cause food spoilage?
e. Which can cause foodborne illness?