Hokkaido University Research Profiles

Life Sciences

Equipment for Simultaneous Optimization of Quality and Quantity of Liquid Ice for Freshness Preservation


  • Yuji Shinohara

Liquid ice optimization system for long-term freshness preservation of food

We have developed a device that calculates the minimum required amount of food-grade liquid ice (slurry ice (salt water ice) or salt-free water ice) using a simple heat capacity calculation, and that also calculates the salt concentration, water/ice mixing ratio, and shelf life to determine the slurry ice temperature based on the overall heat transfer coefficient (container heat radiation parameter) of the storage container.

Content of research

The amount of produced slurry ice, which is useful for maintaining the freshness of marine animals, often exceeded the amount actually used because there was not a calculation method that took storage time into account. At our laboratory, we have developed a device to optimize the quality (salt concentration and water/ice mixing ratio) and quantity (shelf life) of slurry ice simultaneously and quickly on the spot based on the overall heat transfer coefficient of the storage container, as described earlier. Since this method can be applied to the production of fresh water-derived salt-free liquid ice, it can also be used for other food than marine animals (vegetables, fruits, and livestock), and we are currently working to obtain the rights to this invention.

  • Figure. Comparison of the measured and calculated temperatures of slurry ice (upper left: silver-stripe round herring, lower left: sailfin sandfish), and comparison of the measured and calculated amounts of ice in slurry ice (upper right: silver-stripe round herring, lower right: sailfin sandfish (calculated values only))

Potential for social implementation

  • ・Implementation with fishery-related products (e.g., slurry ice production equipment at fishing ports and on fishing boats)
  • ・Implementation with products involved in the distribution industry (fish boxes, storage containers for food transportation, etc.)
  • ・Implementation with retail industry-related products (e.g., low-temperature showcases)
  • ・Implementation with products used by consumers (e.g., refrigerators)

Appealing points to industry and local governments

With this device, the optimum amount of liquid ice to be produced can be determined on the spot and quickly, taking the storage time of the food into account. This is expected to lead directly to lower production costs and lower fuel consumption for fishing vessels.

Intellectual property related to this research

特願2021-137125 「塩分含有水氷及び/又は水氷の製造量算出装置、塩分含有水氷及び/又は 水氷の製造量算出方法、及び、塩分含有水氷及び/又は水氷の製造量算出装置を備えた塩分含有水氷及び/又は水氷製造装置」

PCT/JP2022/010889 「塩分含有水氷及び/又は水氷の製造量算出装置、塩分含有水氷及び/又は水氷の製造量算出方法、及び、塩分含有水氷及び/又は水氷の製造量算出装置を備えた塩分含有水氷及び/又は水氷製造装置」