Fundamental Food Microbiology, Third Edition - Fuad Fathir

304 FUNDAMENTAL FOOD MICROBIOLOGY
9. Lawson, P., Dainty, R.H., Kristiansen, N., Berg, J., and Collins, M.D., Characterization
of a psychrotrophic Clostridium causing spoilage in vacuum-packed cooked pork:
description of Clostridium algidicarnis sp. nov, Lett. Appl. Microbiol., 19, 153, 1994.
10. Yang, R. and Ray, B., Prevalence and biological control of bacteriocin-producing
psychrotrophic leuconostocs associated with spoilage of vacuum-packaged meats, J.
Food Prot., 57, 209, 1994.
11. Whiteley, A.M. and D'Souza, M.D., A yellow discoloration of cooked cured meat
products: isolation and characterization of the causative organism, J. Food Prot., 52,
392, 1989.
QUESTIONS
1. Define psychrophilic and psychrotrophic microorganisms. Discuss why psychrotrophs
are important in food spoilage.
2. Briefly discuss the reasons for the current popularity of refrigerated foods.
3. What are the possible causes of microbiological problems in refrigerated foods?
4. List six bacterial genera or species that are currently designated as new spoilage
bacteria. Explain the possible reasons for their becoming important in the spoilage
of refrigerated foods.
5. A processor recently started producing a new vacuum-packaged, low-heat processed,
low-fat meat product with an expected shelf life of 60 d at 40�F (4.4�C).
He found that ca. 10% of the product was getting spoiled within 30 to 40 d. The
characteristics were accumulation of gas and purge (cloudy), with acidic and
cheesy odor. He asks you to help him determine the causes and resolve the
problem. Explain briefly, in a stepwise fashion, how you plan to proceed in order
to understand the problem (causes, sources, sequence of events, etc.] and solve it.
6. Answer Question 3 to Question 6 in Chapter 3 with the current understanding
from this chapter on the pathogen problems in the listed foods. Suggest their route
of contamination of the respective products and the sequences that lead to the
problem in each case.