Useful by-products from king crab
King crab tails are a little utilized resource, but a study has shown that boiled, peeled crab tails taste great and may be an ideal product for markets including restaurants.
At Nofima in Tromsø, crab meal has been produced from the shell, tails and guts, which proved to be extremely well suited as an ingredient in start feed for lobster. Further, adding this crab meal to salmon feed resulted in increased growth.
The annual catch of king crabs in Finnmark has increased from 50 tonnes in 2004 to 1906 tonnes in 2011. In 2011, live crab exports constituted around 5 % of the market. The remaining 95 % was processed at the processing plant in Finnmark and sold frozen. The by-products account for approx. 32 %, or around 700 tonnes that shall be handled in an environmentally sound manner.
The absence of depots for further handling of this means that consent has been granted for the depositing of these by-products in landfills or at sea. Consequently, companies are inflicted with logistics and handling costs for freezing and / or freight. This is not unlike the situation encountered by the shrimp industry 25-30 years ago.
The main objective of this project, which is financed by the Fishery and Aquaculture Industry Research Fund (FHF), was to acquire knowledge that may contribute to establishing industrial activities based on by-products from king crabs. Scientists have looked at new production lines for crab meal and alternative uses for crab meal and by-products.
During the project period, a simple and functional production line was developed for the production of crab meal based on by-products from the crab industry. The level of chitin in the by-products from the king crabs is high and it may be a suitable source for production of chitin. An amino acid and heavy metal analysis of the king crab meal was also carried out.
“The amino acid in the crab meal was exciting with regard to the use in special feeds for shellfish and as a source of attractants in fish feed. Analyses of heavy metals showed no limitations in the use of crab meal as feed ingredient,” says Project Manager Even Stenberg.
In light of these results, two new dry feeds were developed: a start feed for lobsters and a dry feed for salmon intended for the sea phase. The crab meal proved to be extremely well suited as an ingredient in start feed for lobsters, producing a high survival rate and good growth results. Further, a 2 % additive of the crab meal in the salmon feed produced significantly enhanced growth compared to the feed without the crab meal.
Crab tails and gills
The weight of the crab tails and gills each constitute approx. 3 % of the crab’s weight. In 2011, tails and gills constituted a total of approx. 110 tonnes of by-products.
Tails to the restaurant market?
The muscle from the walking legs is currently the main product from the production of king crab. A sensory evaluation was carried out of crab tails compared to the muscle in the walking legs. The muscle from crab tails has less intensity of shellfish flavour, sweetness and salty taste compared with muscle from the walking legs. In summary, the muscle from the tails was described as having lower intensity of flavour, and hard and tough to chew compared with muscle from the walking legs.
Peeling of crab tails that are frozen then later boiled will take a long time compared to peeling fresh, boiled tails, and is hardly economically viable. A strategy for the industry may be to sell boiled, peeled tails, as an ingredient to the industry or the restaurant market. For the export market, frozen, unprocessed crab tails are in all likelihood the easiest product to sell.
Gills for fish sauce – not necessarily good business
Although fish gills are a sought-after raw material for production of fish sauce, it is uncertain whether king crab gills are equally suitable. The gills have low protein content, and this in turn leads to low protein content in the sauce. Moreover, the sauce yield is also relatively low. However, the yield may be improved by further optimization of the fermentation process.
Further information concerning the methods, analyses and results is included in report 5/2012 “By-products from the king crab” (Paralithodes Camtschaticus), which is published in Norwegian only.