Slurry ice possesses several advantages for seafood preservation, such as faster chilling rate, reduced physical damage, and complete coverage of the fish surface. In this paper, the efficiency of its employment, either applied alone or combined with ozone, was evaluated for bighead croaker and compared with traditional flake ice. Changes of a series of microbial, biochemical and sensory parameters including total viable count (TVC), sensory scores, total volatile basic nitrogen (TVB-N), peroxide value (PV), thiobarbituric acid (TBA), hardness and springiness were investigated up to 21 days. TVC, sensory attributes, hardness and springiness of fish stored in ozonised slurry ice, were significantly different from fish stored flake ice and slurry ice, indicating that a combination of slurry ice and ozone allowed better quality maintenance. Increase in TVB-N, PV and TBA values of the fish treated with ozonised slurry ice and slurry ice were found to be noticeably reduced compared to those of the flake ice ones. Based on the acceptable limits of TVC and other quantifiable attributes, a prolonged shelf life of 18 days was estimated for the bighead croaker stored in ozonised-slurry ice, whereas the counterpart batches treated with flake and slurry ice would exceed these limits after 9 and 15 days, respectively. Additionally, sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and scanning electron microscope observation also revealed that ozonised-slurry ice could effectively retard the degradation of myofibrillar proteins and reduce the deterioration of microstructure.
Keywords: Bighead croaker; Ozone; Quality; Shelf life; Slurry ice.