The proximate composition of three marine pelagic fish: blue whiting (Micromesistius poutassou), boarfish (Capros aper) and Atlantic herring (Clupea harengus)

peer reviewedThis study presents data from an in-depth proximate compositional analysis of three marine fish species: blue whiting (Micromesistius poutassou), boarfish (Capros aper) and Atlantic herring (Clupea harengus). These fish contained significant amounts of protein (16–17%), lipids (4–11%) and minerals (2–6% ash). The proteins, particularly from boarfish, had close to optimum amino acid profiles for human and fish nutrition. They compared favourably with other fish species in terms of total lipids and relative concentration of the omega-3 fatty acids docosahexaenoic acid and eicosapentaenoic acid (11.8–13.3% and 5.9–8.1% in triacylglycerols [TG] and 24.6–35.4% and 5.8–12.0% in phospholipids [PL]). Atlantic herring had the highest lipid content among the three fish and was found to contain high levels of PL poly-unsaturated fatty acids, including omega-3 fatty acids. Minerals detected in the fish included calcium (272–1,520 mg/100 g), phosphorus (363–789 mg/100 g), iron (1.07–2.83 mg/100 g), magnesium (40.70–62.10 mg/100 g), potassium (112.00–267.00 mg/100 g), selenium (0.04–0.06 mg/100 g), sodium (218.00–282.00 mg/100 g) and zinc (1.29–5.57 mg/100 g). Boarfish had the highest ash fraction and also the highest levels of all the minerals, except potassium. Atlantic herring had considerably lower mineral content compared with the other two species and, levels detected were also lower than those reported in previously published studies. Heavy metals contents were quantified, and levels were significantly below the maximum allowable limits for all elements except arsenic, which ranged from 1.34 to 2.44 mg/kg in the three fish species. Data outlined here will be useful for guiding product development. Future studies would benefit from considering catch season, sex and developmental stage of the fish

Microbial oils as nutraceuticals and animal feeds

45 p.-5 fig.-3 tab.Lipids and oils are produced by all single-cell organisms for essential structural and functional roles; however, the term single cell oils (SCOs) is mainly restricted to describe the lipids produced by a limited number of oleaginous microorganisms (archaea, bacteria, yeast, fungi, and microalgae) with oil contents higher than 20% of biomass weigh. SCOs have different fatty acid compositions from those of plant seed or fish oils and are nowadays considered as new sources of nutraceuticals and animal feeds. In spite of the current commercial success of some SCOs, the development of more efficient microbial fermentation processes and the possibility of manipulating by systems metabolic engineering the lipid composition of cells require new biotechnological strategies to obtain high yields of the desired SCOs. Understanding the synthesis and regulatory mechanisms involved in the production of SCOs is fundamental to eliminate the metabolic bottlenecks that impair achieving high oil yields.This chapter is supported by grants from the Community of Madrid and the Structural Funds of the European Union (Ref: S2013/ABI2783 (INSPIRA1-CM)), the Ministry of Economy, the Industry and Competitiveness (Ref: RTC-2016-4860-2; Ref: BFU2014-55534-C2-1-P), and the Intramural Program of the CSIC (Ref: 201420E086) and the H2020 FET-OPEN program (LIAR: Ref 686585).Peer reviewe