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It surrounds the fish and quickly cools it to around -0.5°C and keeps it at this temperature during processing without freezing the fish. Throughout the fishing trip, land transportation and on the way to the final consumer, the temperature of the fish is kept at about -0.5°C.

In the past few years, great progress has been made in the handling of fish. Studies by Matís, the Icelandic Institute of Food and Biotechnology, Akureyri University (Iceland) and other countries have shown that immediate cooling of the catch is a key factor in maintaining quality and extending shelf life.

The Icelanders developed Optimice® pulp ice to replace traditional flake ice.

Optimice® is a rapid cooling system that uses sea water on ships. The liquid slurry ice surrounds the fish, quickly cooling it to below 0°C and keeping the temperature around -0.5°C. Throughout the fishing trip, landing, transport to the manufacturer and final consumer, the fish maintain the same temperature without freezing.

Therefore, with Optimice® rapid cooling, the cold chain will never be interrupted, and the fish will always remain fresh and maintain the highest quality.

Simplify workflow and save time

Since Optimice® slurry ice is made on board, there is no need to produce flake ice on land and transport it to the ship.

This saves time and money, and is more convenient for fishermen. The ice is just poured on the fish in liquid form, where the liquid turns into a cold ice slurry, which completely surrounds the fish and stays for the entire fishing trip.

More than two decades of global experience

Since 1999, Optimice® has been manufactured by KAPP ehf. More than 500 devices have been sold worldwide, and many of the largest shipping companies in Russia, Europe, the United States, Iceland and elsewhere have successfully used the devices.

The quality, reliability and durability of Optimice® pulp ice machines are highly valued because the sea conditions can be very demanding. Reliable production and durable, low-maintenance machines are key. Therefore, all production and inspections are carried out at KAPP ehf in Iceland, following strict quality requirements and ensuring that only the highest quality materials are used. The liquid ice machine is suitable for cold and hot climates where the seawater temperature varies greatly. It is also suitable for small vessels (>10m) and large trawlers, and adapts to the maximum daily catch of each vessel. The Optimice® cooling system is suitable for most fish and has also proven successful in cooling vegetables and dough in large bakeries, although it is most commonly used to cool bottom fish, salmon, and shrimp.

In recent years, studies have shown that the use of Optimice® pre-coolers has achieved good results in processing fish on land. The fish is then cooled regularly during processing, so it will never be heated to the critical temperature where bacterial growth may occur. This greatly improves the quality and shelf life of the fish.

A new study from the University of Akureyri in 2019 shows that if fish fillets are immersed in ice slurry for one minute before packaging, the shelf life of the fish will increase by about one and a half days.

In the same study, the salt intake of cod fillets refrigerated with Optimice® was studied, and the results showed that there was no salt intake at all. In this study, fish fillets were placed in a mud ice bath for 30 seconds to 10 minutes. The results showed that there was no significant difference in salt content according to the length of time the fish was in the mud ice bath, so there was no salt absorption.

The cold chain may never be broken

A new study by the University of Iceland in 2020 examined the effect of ice slurry on the temperature of cod fillets in fresh fish processing plants before the fish is placed in a cold storage or freezer. The temperature of the product, refrigerant, and processing room was monitored, and the results were clear. The inadequate temperature control of the fresh fish cold chain before freezing has a great impact on the quality of the final product.

Therefore, it is important that the cold chain from shipping to the final consumer is uninterrupted in order to maintain quality.

Therefore, in the processing plant, the fish must be quickly cooled to the storage temperature and kept at the same temperature to ensure the highest quality.

In another study, the temperature of the catch was studied at sea until the catch was processed on land. Optimice® cooling system is used on board. The whole catch immediately cooled down. After 7 days of fishing, the catch came ashore and was driven by a truck for 7 hours to the processing plant.

The temperature when the fish arrive is -0.7°C, and the ambient temperature of the processing plant is +20°C. Before processing, put the fish in a buffer tank filled with pre-cooled ice water. The fish is cut into slices, trimmed and finally packaged, but between the two it is transported to a conveyor belt with a built-in pre-cooling device.

During the whole process, the fish went from -0.7°C to +0.6°C. Therefore, the increase is only 0.9°C, but a lower ambient temperature will produce better results. The cold chain is never interrupted, maintaining the highest product quality from the fishing and the entire processing process.

Customer comments support the research results. The following are examples of people who have used a slurry ice cooling system for many years:

Ólafur Rögnvaldsson, CEO of Hellissandur fish processing plant. "It turns out that Optimice® equipment is very suitable for our fishing vessels and land production plants. I recommend this equipment to everyone who handles fish." Hinrik Kristjánsson, CEO of Kambur Seafood. "Our experience with Optimice® is very good. The cooling remains very stable throughout the process from fishing to the final customer. For us, this means that we can get higher fish prices." Pétur H. Pálsson, Vísir Director of a fishing company. "For many years, we have been using Optimice® equipment on our fishing boats. Our experience is excellent. There is no doubt that it provides us with better quality, longer shelf life, reduced labor time and the price of our products. More favorable"

Fast cooling of the catch is the key

Once the fish is caught, its decay will begin, and the faster it is refrigerated, the fewer bacteria will be, the shelf life will be extended and the quality will be maintained.

The figure above shows the difference between using Optimice® slurry ice to cool bottom fish on the one hand and traditional flake ice on the other.

The mud ice system cools the fish to below 0°C in less than an hour. With traditional flake ice, it takes about 15 hours to reach the same temperature.

The difference in quality can be seen in the pictures of the fish taken 14 days after cooling. The upper part is cooled with slush ice and the lower part is cooled with flake ice.

A lot of research on cooling systems has been done and all have shown similar results. The picture above is from Scottish marine fish. Matís, the Icelandic Institute of Food and Biotechnology, Akureyri University, and the International Journal of Refrigeration have also conducted research on slurry ice cooling and published similar results.

Cod after cooling for 14 days.

Visual evolution during sampling 

A study conducted at the University of Iceland clearly showed the difference in the quality of fresh cod during the 14-day period.

The differences between these cooling systems are huge.

The quality of cod surrounded by pulp ice was very good on the fourteenth day, but the quality in the flake ice began to drop a lot on the sixth day, and rot became obvious on the fourteenth day.

Machine for making Optimice® Pulp Ice

The pre-cooler speeds up the cooling process and can be sold separately or together with the Optimice® ice maker.

Optimice® machines make mud ice from sea water.

The storage tank collects and stores ice slurry so that there is always enough ice to cool the fish.

Rapid cooling of fish worldwide since 1999

Accumulated a lot of experience in this technology, more than 500 Optimice® machines have been sold in more than 20 countries around the world for fishing vessels and onshore processing.

Features: The ice slurry is liquid and poured on the freshly caught fish.

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