Cục thủy sản

Liquid ice, also known as slurry ice, snow ice - is a homogeneous mixture of small particles of ice and liquid. Liquid ice has many advantages such as high energy storage density, cooling very quickly due to the very small size of ice particles, so it is easy to penetrate inside the object that needs to be cooled, maintaining constant low temperature during cooling with high heat transfer coefficient. Liquid ice is styrofoam, non-crystalline rock, easy to store and unload, does not cause damage to seafood, minimizes bruising or crushing of seafood during storage. The liquid ice can be adjusted in temperature, because it has a low temperature of -20C ÷ -40C, so the time for preserving aquatic products is from 25-30 days.
Fishing vessels in Vietnam operate offshore for more than 20 days. The exploited products are preserved by crushed stone brought from the shore. Therefore, the quality of the fish plummets after 10 days of preservation, the exploitation time more than 20 days, forcing the ships to sell fish to the sea-collecting vessel at a cheap price. For tuna fishing, there is no purchase at sea, so all catches are brought to the port and sold to the barns, tuna preserved by stone for more than 12 days reduces the quality.
Traditional grinding ice technology is no longer suitable for ships exploiting offshore with long-term sea-clinging time like today. The problem posed in terms of technology solves the problem of extending the storage time in accordance with the time of the sea voyage while maintaining product quality.
For freezing technology, which prolongs the storage time, but the exploited products are frozen. Therefore, the sorting and thawing for sale to the barn becomes difficult and inconsistent with the actual production and reduced product quality during thawing. On the other hand, the scale of fishing vessels in Vietnam is small and mainly wooden ships, so the installation and operation of the freezing system is complicated and consumes a lot of fuel.
Liquid ice technology with the many advantages as above analyzing, it uses directly seawater to produce ice at sea, so it can be actively and maintain a low temperature, suitable for all sizes of ships. The product is preserved by liquid ice although at negative temperatures, the product does not freeze, does not adhere, suitable for the storage time and production methods of most fishing professions in Vietnam.
In other countries around the world, most of the offshore fishing vessels and ocean operators apply the liquid technology to preserve their products. Liquid ice proves its effectiveness for intermediate preservative products before they enter the processing plant. In Vietnam, this technology has just been put to the test, preserved in yellowfin tuna for hand fishing combined with light. The results illustrated that the fish had good biochemical quality, good organoleptic quality, the microorganism in the product was within the permissible limits, the histamine in the fish meat was reduced compared to the fish preserved by grinding ice. In particular, the time to lower the temperature of the fish's heart to 0oC is only 24 hours, while for fish preserved by grinding ice lasts up to 6 days, the temperature of the fish's center is 0oC.

The effectiveness of fish preservation by using liquid ice technology is very good. However, the applying this technology in Vietnam still has problems. Firstly, when applying new technology, the product price does not increase significantly, the reason is that the trading companies require to increase the quality evenly and price will be increased, while the fishermen require the price increase before applying technology to increase the quality - the problem of pushing back and forth has no solution. Second, the habits of shipowners are using the traditional grinding method. The change to the new method completely making it difficult for fishermen to access. Third, the current cost of the equipment system to create liquid ice and store on fishing boats is still high compared to the investment of fishermen.
In order to successfully apply the liquid technology to the offshore fishing, it is necessary to support the state at an early stage and the commercial enterprises invest in a model to create a supply chain of good quality products supplied to the processing factories. The shops then become a goods collection for trading companies, the price of the product announced by the trading company itself according to the production quality scale. When the chain comes into operation and brings efficiency, it will have a positive impact on most other ship owners and they will voluntarily invest when they see a clear economic effect. Ship owners participating in the fleet need to ensure standards for volume quotas, quality of catches and regulatory, commercial and IUU fishing requirements.

In summary, in order to develop a sustainable fleet of offshore fishing vessels, it is necessary to limit the quantity increase and instead focus on increasing quality, reducing post-harvest losses by applying new preservation technology, to improve and settle output prices for fishermen. The liquid ice technology is a suitable choice for marine fisheries in Vietnam and in line with the world and regional trends in the technology of preserving onboard fishing vessels. The support of the state and the participation of commercial companies in the "opening" of the supply chain for fishing products using new technologies will bring about product price efficiency - a core problem of the revolutionary preservation technology on fishing vessels in Vietnam.

Lê Mai