Effect of Fractionation Technology on Nutrient Profile of Protein-Rich Ingredients from Hollow Brown Crab (Cancer pagurus)

Abstract The sustainable utilization of seafood side streams is increasingly recognized as a key strategy to improve resource efficiency and deliver high-quality nutrients. Brown hollow crab ( Cancer pagurus ) represents one such underutilized resource, as the body is typically discarded after claw removal due to its complex composition. Here, we investigated how pretreatments (thermal processing, cleaning) and two separation technologies, i.e., mechanical separation (MS) and alkaline pH-shift processing, affect the nutritional composition of protein-rich products recovered from brown hollow crab. Both techniques successfully recovered residual tissue that was enriched in essential amino acids (203–395 mg/100 g dw), vitamin D (0.048–0.140 µg/100 g dw), and zinc (19–30 mg/100 g dw), with a favorable n-3/n-6 fatty acid ratio (2.9–3.6). The pH-shift method proved more effective than MS in concentrating protein and vitamin D, as it removed the ash-rich shells more efficiently, resulting in products with lower levels of sodium, calcium, magnesium, potassium, and arsenic. Contrary, MS gave higher n-3 PUFA and lower mercury levels; for whole crab, also higher B12 levels. Products produced from whole crabs generally contained higher amounts of total lipids, unsaturated fatty acids, vitamin D, vitamin B12, copper, and cadmium, but had lower essential amino acid content compared to those from cleaned crabs. Overall, this study demonstrates that both biomass pretreatments and valorization technologies significantly influence the macro- and micronutrient profile of products derived from brown hollow crab, providing critical insights for their potential use in sustainable food applications.