Ch. 28 - Applied and Industrial Microbiology

Tortora - Microbiology: An Introduction 14th Edition

Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook

Tortora 14th Edition

Ch. 28 - Applied and Industrial Microbiology

Problem 8

Chapter 28, Problem 8

Which type of radiation is used to preserve foods?
a. Ionizing
b. Nonionizing
c. Radiowaves
d. Microwaves
e. All of the above

Verified step by step guidance

Understand the types of radiation listed: ionizing, nonionizing, radiowaves, and microwaves. Each has different energy levels and effects on microorganisms.

Recall that ionizing radiation (such as gamma rays and X-rays) has enough energy to remove tightly bound electrons from atoms, causing damage to microbial DNA and effectively killing or inactivating microbes.

Recognize that nonionizing radiation (such as ultraviolet light) has less energy and primarily causes damage by creating thymine dimers in DNA, which can inhibit microbial replication but is less penetrating than ionizing radiation.

Consider the uses of radiowaves and microwaves: radiowaves have very low energy and are not typically used for microbial control, while microwaves kill microbes mainly by heat generation rather than direct DNA damage.

Conclude that the type of radiation commonly used to preserve foods by directly killing or inactivating microbes without raising temperature significantly is ionizing radiation.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Ionizing Radiation

Ionizing radiation includes gamma rays, X-rays, and high-energy electron beams that have enough energy to remove tightly bound electrons from atoms, causing ionization. It is commonly used in food preservation to kill bacteria and other pathogens, extending shelf life without significantly raising the temperature.

Nonionizing Radiation

Nonionizing radiation, such as ultraviolet (UV) light, has lower energy and cannot ionize atoms but can damage microbial DNA, leading to microbial inactivation. It is used for surface sterilization but is less effective for deep food preservation due to limited penetration.

Microwaves and Radiowaves in Food Preservation

Microwaves and radiowaves are forms of nonionizing electromagnetic radiation primarily used for heating food rather than preservation. They cause water molecules to vibrate, generating heat, but do not effectively kill microbes or preserve food over long periods.

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Describe an example of bioconversion. What metabolic processes can result in fuels?

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Which one of the following is not a fuel produced by microorganisms?

a. Algal oil

b. Ethanol

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e. Uranium

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The manufacture of paper includes the use of bleach and formaldehyde-based glue. The microbial enzyme xylanase whitens paper by digesting dark lignins. Oxidase causes the fibers to stick together, and cellulase will remove ink. List three advantages of using these microbial enzymes over traditional chemical methods for making paper.

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Textbook Question

Why is a bioreactor better than a large flask for industrial production of an antibiotic?

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Textbook Question

Which of the following reactions is undesirable in winemaking?

a. Sucrose → ethanol

b. Ethanol → acetic acid

c. Malic acid → lactic acid

d. Glucose → pyruvic acid