Nutritional profiling and contaminant levels of five underutilized fish species in Norway

Abstract

Exploring and making use of underutilized marine resources can be a sustainable approach to achieve future demands of fish consumption by the ever-growing population. Five species, namely European plaice (Pleuronectes platessa), European flounder (Platichthys flesus), lemon sole (Microstomus kitt), megrim (Lepidorhombus whiffiagonis), and thornback ray (Raja clavate), often captured as by-catch in Norway, were characterized for their nutritional value and potential accumulation of hazardous components. The proximate composition, protein profile, fatty acid profile as well as essential and toxic trace elements and polychlorinated biphenyls (PCBs) were analyzed. Digestible indispensable amino acid (DIAA) ratios and scores (DIAAS) and contributions of omega-3 fatty acids to the diet were calculated. Analysis on proximate composition revealed low fat contents of 0.74 to 1.25% and sufficient protein contents between 16.9 and 24% in the five species. Results of DIAA indicate a profitable distribution, with contributions exceeding the daily intake recommendations for an adult person related to a 200 g fillet. Moreover, findings on the distribution of eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) showed remarkable results, considering that the investigated species are lean fish. All five investigated fish exceed the recommended average daily intake level (AI) of EPA + DHA in a 200 g portion. As to toxic trace elements and PCBs, no significantly elevated levels were found considering a portion size of 200 g. Consequently, the nutritional quality of the investigated fish can be regarded as profitable with overall low potential health risks.

Enzymatic Hydrolysis of Orange-Footed Sea Cucumber (Cucumaria frondosa)—Effect of Different Enzymes on Protein Yield and Bioactivity

“…Furthermore, freeze-dried sample, hydrolysate without enzyme, hydrolysate using Bromelain + Papain or Alcalase (dry weight) contained a higher concentration of essential amino acids compared to the findings of a previous study conducted by Kendler et al. [66] on flounder, lemon sole, megrim plaice and thornback ray. In addition, the levels of essential amino acids (dry weight) in this study were higher compared to the essential amino acids content of conventional Atlantic salmon [67], indicating that both freeze-dried and hydrolysates of C. frondosa could serve as excellent sources of essential amino acids due to its superb quality proteins.…”

“…In addition, the concentration of free amino acids contributing to bitter flavor was 20 times less in this study compared to Atlantic salmon (dry weight) [75]. However, the composition and properties of small peptides and umami free amino acids play an important role eliciting the characteristic taste of food [66,71,76].…”

“…The free amino acids of freeze-dried and hydrolysate without enzyme, hydrolysate with Bromelain + Papain and hydrolysate with Alcalase of C. frondosa (Figure 3) have been categorized based on their flavor profiles, as described in the studies by Sarower et al [71], Kirimura et al [72] and Fuke and Konosu [73], and as presented in Kendler et al [66]. According to the study by Wang et al [74], glutamic acid, glycine and alanine are identified among the most important umami taste contributors in seafood.…”

“…In addition, compared to other hydrolysates and the freeze-dried sample, the aspartic acid content of the hydrolysate produced using Alcalase was significantly higher (p < 0.05). When sodium salts like monosodium glutamate (MSG) are present, these amino acids may contribute to the umami flavor [66,74].…”

Nutritional Value of Yogurt as a Protein Source: Digestibility/Absorbability and Effects on Skeletal Muscle

“…Milk protein is rich in essential amino acids for humans and has a very good ratio at which it is absorbed and taken up into the body. To reflect this, the digestible indispensable amino acid score of milk protein is particularly superior among these major protein sources [9][10][11]. Milk protein is broadly divided into casein and whey proteins.…”