Microbiological and Sensory Evaluation of Fresh Fish Packaged in Carbon Dioxide for Retail Outlets in the Midwest.

Fresh fish obtained from a commercial packaging plant were evaluated for microbial content and sensory changes during 3 weeks of storage. Fish were packaged in (a) nylon-Surlyn bags and backflushed with approximately 80% CO2, (b) in nylon-Surlyn bags with no alternation of gaseous environment, or (c) over-wrapped with polyvinyl chloride film. After packaging, fish were stored at 1°C. Two types of fish (ocean perch and sea trout) were analyzed. The data indicate that fish packaged in the nylon-Surlyn bag with CO2 had the smallest increase in microbial numbers followed by the fish packaged without CO2. An increase in the bacterial lag phase was observed for the fish packaged in CO2 when compared with fish packaged without CO2 or over-wrapped. The fish packaged in CO2 maintained a lower pH during storage compared with fish packaged without CO2. The highest microbial load was found in fish packaged with the polyvinyl chloride over-wrap.