b. Other waste compounds
ⓐ Collagen
1. Fish skins are of interest the production of fish gelatin from the extracted collagen
2. Fish gelatin differs from animal gelatin : lower content of the amino acids, proline and hydroxyproline
3. Fish gelatin forms a gel at 10-15℃ compared with mammal-derived gelatin gels at 30℃
4. The gels tend to be weaker than those made from mammalian gelatin
5. Used in capsules for the pharmaceutical and light-sensitive coating on photographic films
6. Collagen from cod skin bladders as a clarifier in the Japanese brewing and wine industry
ⓑ DNA and nucleotides
1. Nucleotides can be produced from testes
2. Nucleic acids can be produced from salmon milt
3. Protamine is also present in fish milt and used for cosmetic industry
ⓒ Omega-3 fatty Acids
1. Fish discards, especially the liver, are considerably higher in fat content and fat-soluble vitamins
2. Extraction of these compounds can occur during solid waste processing
3. Production of surimi from high-fat fish (mackerel, sardines, menhaden) will allow direct recovery
ⓓ Antioxidants
1. Carnosine and anserine recently recovered form surimi wash water
2. These compounds to be active antioxidants in different food systems