Date of Award:

5-2014

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Food Sciences

Committee Chair(s)

Marie K. Walsh

Committee

Marie K. Walsh

Committee

Brian A. Nummer

Committee

Robert E. Ward

Abstract

Foodborne illness is a very severe problem, and it is now a serious issue throughout the world. Within the 5 pathogens that cause more than 90 percent of foodborne illnesses, Listeria monocytogenes ranks the third. L. monocytogenes causes the highest death rate among all foodborne pathogens, and it represents high risks to pregnant women, fetuses and people with weak immune systems. Therefore, inhibition of Listeria in food becomes a relevant topic in food industry and scientific field nowadays.

Adding antibacterial agents into food products is considered as an effective method to inhibit Listeria growth. My research was focused on characterization of a novel sugar ester, lactose monolaurate (LML), with respect to antimicrobial activity. Previous research showed that LML was antimicrobial to L. monocytogenes with minimum bactericidal concentrations (MBC) less than 5 mg/mL in growth media. The objectives of this research were to determine if LML showed the same antibacterial activity in various dairy products.

My results found that LML showed a bactericidal effect on Listeria in fat-free milk, fat-free drinkable yogurt, 1% drinkable yogurt, fat-free cottage cheese and 2% fat cottage cheese. With skim milk, whole milk and 1.5% fat yogurt, LML had bacteriostatic effect. Moreover, LML did not show significant inhibition on Listeria in cream. Therefore, the antibacterial activity of LML was dependent on the fat content of the food product.

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