Use of crustacean shells for gourmet dressings and biofertilisers

Problem statement

The shell, including the head, constitutes ͂60 % of the weight of the animal (shrimp, prawn), which can reach several tonnes per day, entailing high transport costs.

Executive summary

A multi-stage process is used to obtain different products. From the initial extraction, the raw material for food is obtained. Subsequently, pigments are obtained and finally chitin, which can be converted into chitosan by deacetylation.

Technology description

Shrimp shells have the highest chitin content, 30-40 %, followed by crab shells, 15-30 %. In the first extraction, raw material is obtained for dressings, from which pâté, soups and premium sauces or for direct application are produced. This is followed by grinding, deproteinisation, demineralisation, filtering and decolourisation. At this point in the process, pigments are obtained that can be marketed.
The decolourisation results in a cake which is washed and dried to obtain chitin. This undergoes a deacetylation process and is converted into chitosan. This is a biopolymer (a polysaccharide) that can be used in a wide range of applications in its different modified forms as well as different degrees of purity. The company Ryomar, which implements this technology, uses chitosan as a biofertiliser in agriculture.
Other potential uses are as a food-grade flocculant in water treatment and paper manufacturing

Market deployment considerations

in edible films or microencapsulation of ingredients in food applications

Environmental considerations

to reduce infections and improve performance in aquaculture and ruminant feed