Date of Award:

1972

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Bacteriology and Public Health

Advisor/Chair:

Dr. G. H. Richardson

Abstract

Attempts were made to adapt the microtiter hemagglutination inhibition assay technique for the assay of enterotoxin A. The presence of a potent hemagglutinin in crude and partially purified preparations and the instability of sensitized erythrocytes prevented its use for routine analysis of enterotoxin from culture media and foods.

A capillary tube immunological assay was developed in which 1 μ g of enterotoxin/ml was detected in less than 1 hr . Interfacial reaction of antisera and enterotoxin solutions in a 1 mm internal diameter capillary tube allowed rapid detection and serological typing of enterotoxins.

Staphylococcus aureus growth and enterotoxin A development in Cheddar cheese slurry was evaluated. S. aureus growth and enterotoxin production occurred at 32 C. in 45 and 60% moisture cheese slurries following inoculation with 10 3 to 10 5 bacteria/gram.

Hydrogen peroxide (0. 5%) treatment of slurry at 37 C did not inhibit S. aureus and enterotoxin A development. Heating slurry at 72 C for 30 min eliminated staphylococci but reinoculation with ripening organisms was essential. Addition of sorbic acid (0. 2 to 0. 3%) to a slurry adjusted to pH 5. 0 with lactic acid, inhibited staphylococci. in milk and slurry. Cheese flavor development was retarded due to inhibition of micrococci and lipolysis. Non-protein nitrogen increases paralleled that of sorbate-free controls. Sorbate treatment was preferred over other treatments .

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Nutrition Commons

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