Masters Theses

Date of Award

5-1994

Degree Type

Thesis

Degree Name

Master of Science

Major

Food Science and Technology

Major Professor

F.A. Draughon

Committee Members

J. Mount, J.L. Wilson

Abstract

Fresh rainbow trout (Oncorhynchus mykiss) fillets were evaluated for microbial safety and an overall quality during storage at 3°C and 10°C. Trout fillets were packaged in a high barrier film in the following atmospheres: air, vacuum, 100% carbon dioxide, 60/40 carbon dioxide/nitrogen, and 10/85/5 carbon dioxide/nitrogen/oxygen. Trout packaged in a modified atmosphere that did not contain oxygen had lower microbial numbers at 3°C and lO'C. Fillets were considered spoiled when the aerobic plate count reached log 8 CFU/g (spoilage reference point). At 10°C, the quality of the rainbow trout began to deteriorate and show signs of spoilage (off odors) after 2 days for fillets packaged in air, vacuum, and 10/85/5 (carbon dioxide/nitrogen/oxygen). At 3°C, the packaged fillets showed signs of spoilage after 7 days for trout packaged in air and 10/85/5 (carbon dioxide/nitrogen/oxygen) and after 10 days for vacuum packaged trout. Fillets packaged in 60/40 (carbon dioxide/nitrogen) and 100% CO2 showed signs of spoilage after day 14 of storage at 3°C. No evidence of Salmonella spp. or Listeria spp. was detected during storage of trout at 3°C or at 10°C on the fillets in the different atmospheres. The results obtained in this study demonstrated that a high concentration of CO2 can extend the shelf life of rainbow trout for at least one week at 3°C by inhibiting the growth of spoilage microorganisms.

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