Microbiology: An Introduction
11th Edition
ISBN: 9780321733603
Author: Gerard J. Tortora, Berdell R. Funke, Christine L. Case
Publisher: Benjamin Cummings
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Chapter 6, Problem 2CAE
Heat lamps are commonly used to maintain foods at about 50°C for as long as 12 hours in cafeteria serving lines. The following experiment was conducted to determine whether this practice poses a potential health hazard.
Beef cubes were surface-inoculated with 500,000 bacterial cells and incubated at 43–53°C to establish temperature limits for bacterial growth. The following results were obtained from heterotrophic plate counts performed on beef cubes at 6 and 12 hours after inoculation:
Draw the growth curves for each organism. What holding temperature would you recommend? Assuming that cooking kills bacteria in foods, how could these bacteria contaminate the cooked foods? What disease does each organism cause? (Hint: See Chapter 25.)
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A batch of turkey rolls (10 lb—approximately 4.5 Kg—each) were cooked to 165°F internal temperature in bags, opened, sliced, vacuum-packaged, and stored at 40°F. The product was expected to have a refrigerated shelf life of 50 days. However, after 40 days, the packages contained gas and approximately 107 bacterial cells/g of meat. The bacterial species involved in the spoilage was found to be Leuconostoc carnosum, which is killed at 165°F. What could be the sources of the bacterial species in this cooked product?
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Chapter 6 Solutions
Microbiology: An Introduction
Ch. 6 - Prob. 1RCh. 6 - Prob. 2RCh. 6 - Prob. 3RCh. 6 - Seven methods of measuring microbial growth were...Ch. 6 - By deep-freezing, bacteria can be stored without...Ch. 6 - A pastry chef accidentally inoculated a cream pie...Ch. 6 - Nitrogen and phosphorus added to beaches following...Ch. 6 - Differentiate complex and chemically defined...Ch. 6 - DRAW IT Draw the following growth curves for E....Ch. 6 - NAME IT A prokaryotic cell hitched a ride to Earth...
Ch. 6 - Two culture media were inoculated with four...Ch. 6 - Two culture media were inoculated with four...Ch. 6 - Use the following graph to answer questions 3 and...Ch. 6 - Use the following graph to answer questions 3 and...Ch. 6 - Assume you inoculated 100 facultatively anaerobic...Ch. 6 - The term trace elements refers to a. the elements...Ch. 6 - Which one of the following temperatures would most...Ch. 6 - Which of the following is not a characteristic of...Ch. 6 - Which of the following types of media would not be...Ch. 6 - An organism that has peroxidase and superoxide...Ch. 6 - E. coli was incubated with aeration in a nutrient...Ch. 6 - Clostridium and Streptococcus are both...Ch. 6 - Most laboratory media contain a fermentable...Ch. 6 - Flask A contains yeast cells in glucose-minimal...Ch. 6 - Clinical Applications and Evaluation 1. Assume...Ch. 6 - Heat lamps are commonly used to maintain foods at...Ch. 6 - The number of bacteria in saliva samples was...
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