11. Controlling Microbial Growth

While hiking, Huda wants to ensure that the river water is clean enough to drink and will not cause any intestinal infections. How could she treat water from a stream so that it is safe to drink?

Lyophilization can be described as ________.

a. freeze-drying

b. deep-freezing

c. refrigeration

d. pickling

A sample of E. coli has been subjected to heat for a specified time, and 90% of the cells have been destroyed. Which of the following terms best describes this event?

a. thermal death point

b. thermal death time

c. decimal reduction time

d. none of the above

The endospores of which organism can be used as a biological indicator of sterilization?

a. Bacillus stearothermophilus

b. Salmonella enterica

c. Mycobacterium tuberculosis

d. Staphylococcus aureus

Which of the following items functions most like an autoclave?

a. boiling pan

b. incinerator

c. microwave oven

d. pressure cooker

The preservation of beef jerky from microbial growth relies on which method of microbial control?

a. filtration

b. lyophilization

c. desiccation

d. radiation

Which of the following types of radiation is more widely used as an antimicrobial technique?

a. electron beams

b, visible light waves

c. radio waves

d. microwaves

In practical terms in everyday use, which of the following statements provides the definition of sterilization?

a. Sterilization eliminates all organisms and viruses.

b. Sterilization eliminates harmful microorganisms and viruses.

c. Sterilization eliminates prions.

d. Sterilization eliminates hyperthermophiles.

Describe five physical methods of microbial control.

What is the difference between thermal death point and thermal death time?

Defend the following statement: “Pasteurization is not sterilization.”

Compare and contrast desiccation and lyophilization.

Hyperthermophilic prokaryotes may remain viable in canned goods after commercial sterilization. Why is this situation not dangerous to consumers?

What are some advantages and disadvantages of using ionizing radiation to sterilize food?

How can campers effectively treat stream water to remove pathogenic protozoa, bacteria, and viruses?