High processing temperatures, exposure to air or prooxidative components can lead to the loss or destruction of healthy nutrients, while microbial contamination during storage is a significant issue. These underline the importance and need for efficient, innovative processing technology that can produce high quality products from pelagic species.
In order to guarantee such products to consumers, a new project called ProHealth is being developed in Norway, Ireland, Poland and Italy. Its main aim is to establish a comprehensive toolbox of optimised existing and novel technologies for developing healthy, high quality, safe and sustainable fish products from pelagic species. The project is also designed to promote consumer acceptance and consumption of pelagic fish products.
‘Pelagic fisheries are important in several countries in Europe,’ said Professor Turid Rustad, coordinator for ProHealth at the Norwegian University of Science and Technology (NTNU).
‘Several of the project's partners have worked on the preservation and processing of pelagics before and we decided to form a consortium and apply for a research project following a call from the Joint Programming Initiative - A Healthy Diet for a Healthy Life (JPI - HDHL).”
The ProHealth toolbox contains information on different preservation methods including superchilling, in which products are chilled to a temperature that is close to or below the initial freezing point, around -2°C. Studies have shown that compared to freezing, superchilling prolongs shelf life without any significant negative effects on quality because it inhibits most autolytic and microbial changes in fish.
For mackerel, it's a particularly promising technique with regard to microbial stability, but must be optimised further to increase texture. Other methods include washing fish with ozonated water, which has Generally Recognised As Safe (GRAS) status and leaves no residue, although more research into the effects on the microbiological and chemical quality of fish is still required.
High Pressure Processing (HPP) is also included. This method involves treating raw materials with 200 to 800 MPa of pressure at temperatures between 5°C and 35°C. This changes the cell membrane and cell structure and inactivates microbes and living bacteria but may also affect the properties of the raw material at the same time and influence colour, texture and lipid stability. HPP is usually carried out on packaged products to decrease the likelihood of recontamination.
‘We have also studied the use of a milder heat treatment called sous vide cooking and model products have been developed. This will better preserve the healthy components included in fish. ProHealth also includes packaging methodology such as modified atmosphere or a cold atmospheric plasma system, which is a novel packaging technology that's industrially adaptable and requires little energy. However, there is a need for further information on the effect this has on fish quality and safety,’ said Professor Rustad.
The research involved in ProHealth was an integrated approach with the expertise of several research and academic groups. Industries from Norway, Poland and Ireland are also members of the project's advisory board. NTNU, the first partner, has a strong record in fish raw material biochemistry and quality as well as changes that occur during storage and processing, especially in superchilling and freezing.
The second partner, SINTEF Ocean in Norway, specialises in fish raw materials, fish lipids, metabolites and processing. The third, Teagasc, Ireland's Agriculture and Food Development Authority, specialises in new processing methods including high pressure preservation and ozone treatment while the fourth partner, Poland's National Marine Fisheries Research Institute (NMFRI) has expertise in consumer research, fish chemistry and processing. The fifth partner, the University of Perugia in Italy, specialises in methods that determine nutrient bioactivity.
‘ProHealth focuses on species such as mackerel, herring and sprat,’ said Professor Rustad.
‘Today, most of the Atlantic herring and mackerel landed in Norway and Ireland is frozen and exported to other countries for processing. Most of the Baltic pelagic fish, such as sprat and herring, are used for fishmeal because of the lack of a consumer market. Meeting consumer expectations for healthy food by using pelagic fish will increase consumption and local processing.’