Quality of crude fish oil extracted from herring byproducts of varying states of freshness

Herring byproducts were stored at 2 and 15degreesC for up to 72 h. Over time, significant increases of total volatile bases (TVB), histamine, putrescine, cadaverine, and tyramine were detected. However, only tyramine and TVB levels were temperature-dependent. The level of total polyunsaturated fatty-acids (PUFAs) was constant. Longer byproducts storage gave rise to an oil with higher levels of free fatty acids, eicosapentaenoic acid (EPA), docosahexaenoic acid (DRA), and total PUFAs, while fluorescent compounds were lower. A higher storage temperature led to oil higher in alpha-tocopherol and EPA levels and lower in anisidine value. Surprisingly, the oil with the highest content of PUFAs was not produced from the freshest byproducts, and oil With low oxidation products can be extracted from stored byproducts.