11. Controlling Microbial Growth

Pasteurization is what type of microbial control method?

How does desiccation control microbial growth?

This method of physical microbial control combines the removal of all moisture with extremely low temperatures.

How does irradiation control microbial growth?

A heat-sensitive liquid in a laboratory has been contaminated with E. coli bacteria. Which form(s) of microbial growth control could you use to remove this E. coli population from the liquid?

How does high pressure processing (HPP) control microbial populations?

How do salts and sugars preserve foods? Why are these considered physical rather than chemical methods of microbial control? Name one food that is preserved with sugar and one preserved with salt. How do you account for the occasional growth of Penicillium mold in jelly, which is 50% sucrose?

Which of the following does not kill endospores?

a. autoclaving

b. incineration

c. hot-air sterilization

d. pasteurization

e. All of the above kill endospores.

Which of the following cannot be used to sterilize a heat-labile solution stored in a plastic container?

a. gamma radiation

b. ethylene oxide

c. supercritical fluids

d. autoclaving

e. short-wavelength radiation

Which of the following is most likely to be bactericidal?

a. membrane filtration

b. ionizing radiation

c. lyophilization (freeze-drying)

d. deep-freezing

e. all of the above

The term 12D treatment refers to

a. heat treatment sufficient to kill 12 bacteria.

b. the use of 12 different treatments to preserve food.

c. a 10¹² reduction in C. botulinum endospores.

d. any process that destroys thermophilic bacteria.

Which type of radiation is used to preserve foods?

a. ionizing

b. nonionizing

c. radiowaves

d. microwaves

e. all of the above

Why is a can of blackberries preserved by commercial sterilization typically heated to 100°C instead of at least 116°C?

Foods packed in plastic for microwaving are

a. dehydrated.

b. freeze-dried.

c. packaged aseptically.

d. commercially sterilized.

e. autoclaved.