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Ch. 28 - Applied and Industrial Microbiology
Tortora - Microbiology: An Introduction 14th Edition
Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook
All textbooksTortora 14th EditionCh. 28 - Applied and Industrial MicrobiologyProblem 9
Chapter 28, Problem 9

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

Verified step by step guidance
1
Step 1: Understand the context of winemaking and the role of each reaction. Winemaking primarily involves fermentation, where sugars are converted into ethanol by yeast.
Step 2: Analyze each reaction: (a) Sucrose → ethanol represents the fermentation of sugar to alcohol, which is a desired process in winemaking.
Step 3: Reaction (b) Ethanol → acetic acid involves the oxidation of ethanol to acetic acid, which leads to vinegar formation and spoilage, making it undesirable in winemaking.
Step 4: Reaction (c) Malic acid → lactic acid is malolactic fermentation, a process that softens wine acidity and is often desirable in winemaking.
Step 5: Reaction (d) Glucose → pyruvic acid is a step in glycolysis, a normal metabolic pathway leading to fermentation, so it is not undesirable.

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Key Concepts

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

Fermentation in Winemaking

Fermentation is the biochemical process where yeast converts sugars like sucrose and glucose into ethanol and carbon dioxide. This reaction is essential in winemaking as it produces alcohol, the primary desired product, and influences the wine's flavor and aroma.
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Acetic Acid Formation and Wine Spoilage

The conversion of ethanol to acetic acid is typically caused by acetic acid bacteria and is undesirable in winemaking. This reaction leads to vinegar-like off-flavors, spoilage, and a decrease in wine quality, making it a negative reaction to avoid.
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Malolactic Fermentation

Malolactic fermentation is a secondary fermentation where malic acid is converted into lactic acid by bacteria. This process softens the wine's acidity, improves mouthfeel, and is generally considered beneficial in many wine styles.
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Related Practice
Textbook Question

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

2
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Textbook Question

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

a. Algal oil

b. Ethanol

c. Hydrogen

d. Methane

e. Uranium

2
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Textbook Question

Which of the following reactions is an oxidation carried out by A. ferrooxidans?

a. Fe²⁺ → Fe³⁺

b. Fe³⁺ → Fe²⁺

c. CuS→ CuSO₄

d. Fe⁰ → Cu⁰

e. None of the above

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Textbook Question

Which type of radiation is used to preserve foods?

a. Ionizing

b. Nonionizing

c. Radiowaves

d. Microwaves

e. All of the above

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Textbook Question

Label the trophophase and idiophase in this graph. Indicate when primary and secondary metabolites are formed.

Textbook Question

Van Leeuwenhoek was the first to see this budding microbe with a nucleus and cell wall; although humans have used it since before the beginning of recorded history, Louis Pasteur was the first to figure out what it does.