Is it possible to serve industrially prepared convenience food that have gourmet quality? Nofima’s scientists, experts in the field of gastronomy and consumers believe that the answer is “yes”. Low temperature and long time (LTLT) is the solution for many meat products.

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Anne-May Johansen  

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You’ve probably tasted a Fjordland or Nortura product that is ready for heating? These products are made as sous vide dishes that are vacuum packaged and then heat-treated in the packaging. This is the same method that has now been tested with a view to achieving higher quality convenience foods. What is new is that now, the products are not given rapid heat treatment at high temperatures, but are treated long-term at gentle process temperatures – Low Temperature and Long Time.

– The method has been used by the culinary industry to achieve extra tender meat, but has not been developed in Norway for sous vide dishes on an industrial scale, says Nofima’s Senior Scientist Jan Thomas Rosnes.

Together with his colleagues Dagbjørn Skipnes and Line Bach Christensen, he has carried out research on how heat treatment, tenderising enzymes and microbial safety are linked using this method.

More tender meat

At a constantly increasing rate, both institutional and private households are moving from traditional chef-prepared methods to serving food cooked using more advanced techniques. Sous vide technology, where products are packaged in a bag before heat treatment, provides opportunities to create fantastic products where both taste and nutritional quality are high. This method’s potential is, however, not fully exploited using ordinary sous vide processing, largely because of the requirements for shelf-life and turnover time in the value chain. The requirements relating to shelf-life – the microbiological quality – have an impact on taste and appearance – the sensory quality.

– Our goal, therefore, was to use low temperatures, so that the enzymes that are a natural part of the meat can tenderise it, and in this way make use of a type of industrial gastronomy, the scientist explains.

Enzymes, in addition to heat treatment at low temperatures for many hours, result in the connective tissue (collagen) in the meat being broken down and the meat becoming more tender.

Six new products

Fjordkjøkken AS, which produces the Fjordland products, Natura SA and Vilteksperten AS are participant companies inn LTLT. In association with the Norwegian Institute of Food, Fisheries and Aquaculture (Nofima) and The Culinary Institute of Norway (Gastanomisk Institutt), culinary expertise and research were brought together.

And the project has already yielded tangible results: as many as six new commercial LTLT products have been launched in stores during the project period. Fjordland has launched an autumn stew with lamb, pulled meat and the LTLT product “Long Cooked pork neck with apple, cranberry and mashed potatoes.” The latter has been particularly well received in the market, and has sold very well. In the summer months of 2015, Nortura launched several products, including Pork belly, XL Spareribs and Schweinhaxe (roasted pork knuckle) which are produced using the LTLT method.Work has been done to facilitate the use of more venison and wild game and seasonal products for the barbecue and summer sector have been developed. Vilteksperten also participated with raw materials from reindeer, elk and deer. A significant number of test productions runs have been completed at both Fjordkjøkken and Nortura, allowing the industrial partners to be actively engaged in the development process. This has resulted in the industry’s stake in the project exceeding 50 per cent.

“It is important to point out that this would not have been possible without close cooperation between scientists and industrial companies. The industrial companies have contributed very actively and have immediately used information gleaned from the project directly in their own product development. Fjordland and Nortura have carried out significant product development and have marketed products in the consumer market”, says Jan Thomas Rosnes.

Three ideas

Three development ideas formed the basis for starting up the LTLT project in 2013:

  • At the beginning of the project, the participating production companies (Fjordkjøkken AS and Nortura SA) had the equipment and the systems needed for heat treatment, packaging and distribution. One basic idea was to exploit this equipment better and more effectively, which can be achieved by long-term heat treatment, where it can be used during the night and at weekends.
  • A second basic idea was to exploit the cuts of meat which today are used to produce minced/ground meat and instead use this quality for the production of processed meat. Far too many parts of slaughtered animals are currently being used for making minced meat because consumers do not know how these raw materials should be processed, and do not have enough time to process them correctly.
  • A third idea was to develop traditional products, which can be served seasonally, such as game meat products, and in this way increase the share of high-grade products from Norwegian raw materials.

Throughout the project, various types of meat, beef, pork, chicken and a range of game meat have methodically been tested to ascertain which types and which cuts of meat are best suited to long-term heat treatment.

Various combinations of time and temperature, ranging from 56 to 80oC, with heat treatment from two hours and up to three days and nights have been tested.

The meat has also been heat-treated with and without marinades.

“In this project, we have used low heat treatment temperatures in the 56 to 80oC range. This is a temperature range where many bacteria can survive. The combination of temperature and heat treatment time, along with the compounds in the product itself, are therefore important. Heat treatment below 60 oC will, to an increasing degree, depend on the time it takes to achieve a sufficient reduction in bacteria count”, explains Jan Thomas Rosnes.

The lowest temperature normally recommended for sous vide is 54.4oC. Below this temperature, some bacteria begin to grow rather than get killed. It is therefore important to use the correct combination of time and temperature if we are to achieve safe products, the Nofima scientist stresses.


Durability tests of up to six weeks have been carried out on the LTLT products produced using different time and temperature combinations. The durability tests show that food safety with regard to bacteria in LTLT-processed products corresponds to what one finds in industrial heat treatment with higher pasteurisation temperatures.

The LTLT project under Nofima’s auspices has now been formally brought to an end, with good results. However, the R&D work continues. There is still work to be done and there are lots of opportunities to further increase the product quality for the consumer and to increase the sustainable exploitation of animals. There is a clear potential for increased earnings.

The Norwegian Centre of Expertise Culinology (NCE Culinology) is a long-standing cooperation between industrial partners and R&D stakeholders with a view to systematising gastronomic knowledge and practice, so that the food industry can use this when developing new products. The cooperation has led to a range of new products and product enhancements. In the context of this project, NCE has played a role in information dissemination and connections with professional culinary circles.

“The research work carried out on enzymatic tenderization has shown that this can be an important way to improve the meat’s texture and quality characteristics. In a bio-economic perspective, much work has still to be done both for utilising the methods developed in the project and in further research to exploit the entire animal in a more sustainable manner. New research in this area between the industry and the institute is being planned. Barbecue products based on LTLT form a segment that was started in the project, but here we still lack some knowledge and the development of new products”, concludes Jan Thomas Rosnes. 

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