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Temperature of Seafood Displays in Commercial Merchandisers

The temperature of seafood and fish in retail seafood display cases is affected by the lighting within the display case, which cause temperatures to rise beyond the ideal 29° F (-1.6° C) to temperatures where bacteria grow exponentially. Even a minor increase in surface temperature such as 2 degrees can be dangerous, posing a serious health risk.

Yet the real surface temperature of refrigerated food displays is often 10 or more degrees higher than the temperature reported by the display case thermometer, and radiation from light can increase surface temperatures by 20° F, which is clearly unacceptable and unsafe. A single experience of food poisoning is enough to lose customers.

Unrefrigerated Icebed Retail Seafood Display Cases

Unrefrigerated display cases rely on ice to control the temperature of the seafood. However, the air two inches above the ice has been measured at room temperature. Other researchers have found temperature differences of up to 25° F between fillets sitting on the icebed and those at the top of the stack in unrefrigerated fish display cases.

At these high temperatures, bacteria grow exponentially, making the fish and seafood unsafe. Controlling the temperatures of fish and seafood displays with both ice beds and refrigeration maximizes seafood shelf life, though humidifiers may need to be added to offset the dehydration caused by the refrigeration process.

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Temperature and Shelf Life of Retail Seafood Display Cases

Storage temperature has a profound effect on the shelf life of fish, though variations can occur depending on the species. One study found that cod fillets at 32° F lasted 14 days; at 39° F they lasted 7 days; and at 56° F they lasted 3 days. Other types of fish spoiled after one day at 50° F to 69° F, and 5 to 16 days at 32° F to 36° F. Fish kept frozen at -22° F can last from 9 months to 2 years.

While merchandising seafood is often a compromise between prolonging shelf life and visually presenting the seafood, every effort to control display case temperatures can have an impact on shelf life.

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For seafood science references and excerpts click here.

Promolux Low Radiation Display Lamps

Compared to other fluorescent lighting, Promolux Safe Spectrum lamps emit 86% lower UV B radiation, a shorter wavelength that penetrates and causes heating, and 52% lower UV A radiation, a longer wavelength that tends to affect surfaces. Because Promolux lamps are designed for true color definition, they have a more balanced visible spectrum than other fluorescent lamps.

Yellow and green wavelengths are the most damaging wavelengths in the visible spectrum, and their predominance in regular fluorescent lighting can distort the natural colors of finfish and seafood and make ice beds look green or yellow. Promolux lamps emit a more balanced range of wavelengths, including more of the red and blue wavelengths and more moderate levels of the yellow and green wavelengths. It is impossible to create a natural light that does not have any yellow or green wavelengths, so light sources will always be damaging to some extent.

However, since Promolux Safe Spectrum lamps minimize the emission of damaging visible spectrum and UV wavelengths, using Promolux lamps will prolong the shelf life of fish and seafood and maximize their fresh appearance, enticing customers to buy while the seafood is fresh.