Food production significantly contributes to climate changes, with the food supply chains generating 21-37 % of greenhouse gases [1]. One-third of this food is further wasted or lost [2]. Food loss and waste is a priority area in the Action Plan for the European Circular Economy and particularly the Farm to Fork Strategy [3]. In this regard, utilizing side-streams for obtaining functional and nutritional ingredients for innovative applications is a promising strategy.

In the framework of the “Up4Food” project (Upcycling side-streams for sustainable and healthy ingredients and new food concepts), researchers from five countries collaborate to improve food resource use by applying a systems approach to recycle processing side-streams from three key industries in Europe: potatoes, oil seeds, and pelagic fish. The ingredients extracted from these side-streams are rich sources of minerals and antioxidants [4], proteins, essential amino acids, fibers, omega-3 and other bioactive fatty acids [5] that have a high value potential for the development of new food products or be used as supplement. To enable the development of healthy and sustainable new food products based on these side-streams, it is essential to evaluate the nutritional quality and food safety of the side-streams, extracted ingredients and new food products.

In this work, a multi-elemental method based on inductively coupled plasma-mass spectrometry (ICP-MS) was optimized for the determination of the (total) levels of 25 trace elements (TEs) in a selection of fish-based side-streams such as backbones, skins, heads and viscera. The method accuracy was assessed by the analysis of spiked side-streams at least at three different levels.

It is worth to note that although ICP-MS has become a routine technique for the determination of TEs in a large variety of (food) samples, its application to the analysis of side-streams products, which are sometimes of higher complexity compared to food products, is still challenging. Also, the method validation is intricate due to the large number of analytes and their very variable levels in such products.

The levels of TEs (25) were classified according to their contribution to hazard exposure or their contribution to nutritional quality in the samples. Three categories were defined: i) potentially toxic trace elements (PTTEs) such as Pb, Cd, Hg and As, ii) essential TEs (ETEs) such as Na, Mg and Fe, and iii) other TEs (potentially in forms other than ionic, i.e. nanoparticles) such as Ag and Ti. The results were compared to published data on similar sources and evaluated in relation to EUs toxic reference values in the food.

The analytical method employed in this study is capable of detection and quantification of a large panel of elements at trace and ultra-trace levels, hence providing very useful insights concerning the risk related to the consumption of the novel food products proposed by the Up4Food project.