In the Kælibót project, Matís has worked on extensive experiments in the field of cooling catfish from target to market, together with Icelandic partners who are connected to the chain's various links, from raw material handling, processing and transport to the market.
The objectives were to compare the cooling capacity of different ice media, cooling methods during processing, the effect of different packaging for product packaging and different transport methods (ships and flights) and the effect of improved temperature control during the transport of chilled products. The project is funded by AVS and the Rannís Technology Development Fund. Matís' partners in the project are Brim hf., Eimskip hf., Icelandair Cargo, Optimar á Íslandi ehf., Samherji hf., Samskip hf., Skaginn hf. and Faith. The project was also carried out in parallel with the European project Chill-on, which is funded by the 6th Framework Framework of the European Union.
Studies on cooling rate, storage temperature, efficiency and energy consumption in cooling raw materials indicated that the best procedure for cooling fish is that the initial cooling on board is carried out with liquid ice. However, it is preferable to store the raw material for a longer period of time in conventional ice cream, especially with regard to the salt absorption of the fish muscle and microbial growth.
Cooling of processed products is also very important because it minimizes the need for refrigeration after the products have been packaged. The explanation for this is that the insulation of packaging can slow down considerably at the cooling rate even if the environment is at the right temperature. Cooling during processing is therefore absolutely essential to maintain the freshness as much as possible and extend the shelf life in such conditions. In this connection, the best results are achieved with skin cooling of fillets. Skin cooling of fillets made from fresh raw materials can extend the freshness time and shelf life by 25% based on the best storage conditions (-1 ° C). For example, it is very important to avoid processing older raw materials before new raw materials in daily production in order to minimize fillet pollution. Pollution caused by damaged microorganisms can lead to faster deterioration of freshness and shortening of shelf life. If good production practices are ensured, pollution is kept to a minimum, for example with adequate liquid regeneration and cooling of products, liquid cooling should be able to yield good results. The increase in value of fish products can be achieved by following these tips and choosing transport routes that minimize temperature fluctuations early in the life of the product in order to maintain freshness for as long as possible.
Temperatures in the flight and shipping of fresh cod were mapped in February and March 2009 from the North to Bremerhaven in Germany. Foam plastic boxes were used, each carrying 5 kg of knuckles. Thermometers were used to monitor product and ambient temperatures and humidifiers measured ambient humidity. The results showed very good temperature control in shipping. Preliminary indications of a comparison between air and ship transport showed a similar total shelf life in the days after fishing, whichever method was used. In flight, there are more temperature fluctuations but a shorter time from the manufacturer to the market. Packaging and time to raise the temperature are important here.
Comparative studies on the insulation value of two types of packaging for fresh fish, i.e. corrugated plastic and foam plastic, have shown the superiority of the foam plastic in this respect. However, the importance of insulating packs is less in the case of whole pallets rather than individual boxes. If the product is not well pre - cooled before packing, less insulation is actually desirable, but then it must be ensured that the temperature control in the transport process is very good.
It is not uncommon for products to be gas-packed abroad, as the product life is based on the packing date. Therefore, the effect of gas packaging and subcooling on the shelf life of cod fillets from different raw materials was investigated. It can be concluded from the experiment that there are very limited benefits from gas packaging and subcooling if the raw material is old. On the other hand, if freshly caught fillets are gas-packed and stored in the best conditions in subcooling, a much longer freshness period and shelf life can be achieved, and thus a much more valuable product than with traditional packaging.
Procedures and handling of raw materials and fish must be observed, and efforts must be made in the handling, processing and transport of fish products to ensure better quality and more valuable products. Although increased quality does not always lead to greater value immediately, increased quality will be more effective in the future and great market interests are at stake for the nation. It does not help to build up and strengthen the image of Iceland and Icelandic products in these times.
Work is now underway to set up practical guidelines on the World Wide Web for cooling and handling fish at all levels of the value chain from target to market. The guidelines are based on the research that has been carried out within the cooling projects Chill-on, Simulation of cooling processes and Cooling improvement, as well as other research. The results of the experiments will be communicated in such a way that companies can easily utilize information and are quick to identify new opportunities to improve internal processes. The information will therefore be presented in a simple and graphical way. Reference will be made to additional material that will be available in electronic form for those who want more and deeper information.
To begin with, the greatest emphasis will be on the processing of catfish (cod) into chilled products, but the aim is for further development where more fish species and other foods and more product categories will be included.
For further information, contact María Guðjónsdóttir, maria.gudjonsdottir@matis.is.