The increase in the global population demands more biomass from the ocean as future food and feed, and the mesopelagic species might contribute significantly. In the present study, we evaluated the food and feed safety of six of the most abundant mesopelagic species in Norwegian fjords. Trace elements (i.e., arsenic, cadmium, mercury, and lead), organic pollutants (i.e., dioxins, furans, dioxin-like polychlorinated biphenyls, and polybrominated flame-retardants), and potentially problematic lipid compounds (i.e., wax esters and erucic acid) were analyzed and compared to existing food and feed maximum levels and intake recommendations. Furthermore, contaminant loads in processed mesopelagic biomass (protein, oil, and fish meal) was estimated using worst-case scenarios to identify possible food and feed safety issues. While most undesirables were low considering European food legislation, we identified a few potential food safety issues regarding high levels of fluoride in Northern krill, wax esters in glacier lanternfish, and long-chain monounsaturated fatty acids in silvery lightfish. Our estimates in processed biomass indicated high levels of undesirable trace elements in the protein fraction, frequently exceeding the maximum levels for feed ingredients. However, in fish meal, almost no exceedances were seen. In the oil fraction, dioxins and furans were above the maximum levels, given for food and feed ingredients. The present study is crucial to enable an evaluation of the value of these species; however, more data is needed before proceeding with large-scale harvesting of mesopelagic biomass.

Animal farming is a fast-growing sector which demands a large supply of feed materials and the search for novel feed ingredients with a smaller impact on the global environment has been intensified. However, before the inclusion of these feed ingredients in animal feed, a preliminary assessment of the quality and performance is needed. This evaluation is usually done by in vivo feeding trials, but in vitro digestion methods have been successfully used for gathering information regarding the nutritional value of the different feed components. Therefore, in this work, an in vitro digestion method was developed using black soldier fly (BSF) larvae meals. The method included seven experimental variables, namely: pH in stomach, pH in intestine, reaction time in stomach, reaction time in intestine, enzyme concentration in stomach, enzyme concentration in intestine and temperature. The experimental variables were screened by means of a fractional factorial design (2^7-2) that allowed to select the concentration of enzyme in the intestine and temperature (at 7 U and 37 °C, respectively) as the most influential factors on amino acid and mineral solubility in BSF larvae meal. Performing the in vitro digestibility at 37 °C with pH of the stomach and intestine at 2 and 9, reaction time in the stomach and intestine at 1 hour and 4 hours and concentration of enzyme in the stomach and intestine at 1 U and 7 U resulted in the highest overall nutrient solubility. This optimised in vitro digestion methodology was used to assess the nutritional stability of three batches of BSF meals delivered by the same producer. The in vitro digestion method was able to reveal differences between the three batches of BSF meals.