The project is divided into two sections: 1) Fish scales and 2) Vitamin D
Domestic fish side streams are under-exploited, and one potential source of added value components is fish scales. Fish may release scales in handling at the harbour. In addition, some fish species are scaled for the market. Scales are waste for the industry. It is estimated that up to ca 10-20 tn of the scale waste is generated annually. The exact mass and geographical distribution of this side stream is, however, unknown. It is known that scales contain high value biomolecules.
To our knowledge, only imported chitin is available in Finland at a moment. However, the possibility to produce chitin/chitosan from domestic sources might create new potential business opportunities for fish industry in the future. Therefore some preliminary studies are needed. As the composition and bioactivity of chitin may vary between scales of different fish species, scales obtained from at least two domestic fish species, e.g. Baltic herring and white fish should be studied. Also the efficiency of the various extraction methods, preferably eco-friendly, should be tested. The obtained information can then be used to preliminary feasibility evaluation.
Numerous studies have shown that a low vitamin D status is a global problem. Vitamin D is naturally present in only a limited number of foods. According to our studies fish is an excellent source of vitamin D, but there is huge variation in the vitamin D contents. There exists variation between and within different fish species. Even the individual variation is high and it is not explained by the diet, fat content, season, weight, sex, and age. The origin of vitamin D in fish is still a mystery and needs further research.
Vitamin D production may be an inherited trait, and possibly affected by one gene, which could explain the differences between individuals. The aim of this section is to test this hypothesis by analyzing the variation of vitamin D contents in Luke’s King-rainbow trout population which genetic variation is known to be low.