Evaluation of a sub-micron slurry ice system compared to a conventional slurry ice system
Ice-based systems of preservation increase shelf life and preserve the quality of a product. The popular forms of product storage include refrigerated seawater, flake ice, and slurry ice. In this study, sub-micron ice crystals were produced from 3.5% salt brine to form a modified slurry ice (NanoICE, Inc, Seattle, WA). The objective of this study was to evaluate the chilling rate and cooling curves of sub-micron ice compared to conventional slurry ice. The following factors were compared: cooling rates as impacted by ratio of sub-micron ice to fish (1:1, 1.5:1, 2:1); handling technique for submicron ice: drained vs not drained submicron ice; 2:1 submicron (drained or not drained) vs 2:1 conventional slurry ice (not drained). Temperature was monitored by inserting thermocouple wires into the geometric center of the whole fish. Fish were incubated to 18°C prior to respective ice treatment. All treatments were concluded when the thermocouples demonstrated an increase in temperature above 4°C. Results indicated that 2:1 ice:fish ratio of sub-micron ice kept the fish below 0°C and below 4°C significantly longer than 1:1 or 1.5:1 (p < 0.05). Not allowing the sub-micron ice to drain from the cooler allowed for a significant decrease in the lowest temperature of the fish when compared to drained sub-micron ice, as well as significant differences in time below 0°C and below 4°C (p < 0.05). Regardless of handling technique of sub-micron ice (drained or not drained) it kept fish below 0°C and 1°C longer than conventional slurry ice (p < 0.05). Results suggest that cooling rates do occur faster with submicron ice, than with conventional slurry ice. In addition, lower temperatures are maintained for longer time periods using sub-micron ice than slurry ice. As a result, quality and shelf-life of fish may be improved using sub-micron ice.