Characterization of Nutritional and Potentially Toxic Elements in Side-Streams and Oil from Herring (Clupea harengusL.) from Norway for Sustainable Ingredient Valorization

This study reports primarily the levels of potentially toxic trace elements (PTTEs) in herring side-streams (skin, head, backbone, belly flap, viscera, and their mixture) and oils as raw materials for new ingredients and foods. Levels of 25 elements were determined by inductively coupled plasma-mass spectrometry after acidic digestion. Samples with Hg and As levels >limit of quantification (LQ) were analyzed by high-performance liquid chromatography (HPLC) coupled to ICP-MS to quantify inorganic and methylmercury species and the inorganic As (iAs) fraction. The levels of Pb and Hg in all side-streams were