Marine Phospholipids

Every phospholipid carries two addresses. The first is written in its polar headgroup — choline makes it phosphatidylcholine (PC), ethanolamine makes it phosphatidylethanolamine (PE), and so on — and it is this address that decides how the molecule behaves at an oil-water interface and whether it will stack into a bilayer. The second address is the fatty acid sitting at the sn-2 position of the glycerol backbone, and it is there that marine sources play a card vegetable lecithin never draws: in krill, roe and squid phospholipids, the sn-2 seat is routinely occupied by EPA or DHA. Soybean lecithin has the headgroups but linoleic tails; fish oil has the tails but no headgroup at all. Only marine phospholipids put both in a single molecule that can still self-assemble.

Eata Marisource supplies phospholipid-rich fractions from Antarctic krill, salmon roe, squid and fish by-products — as de-oiled powders, fluid lecithins and PC-enriched concentrates — each lot traced back to its raw-material stream and released against phospholipid class composition, omega-3 acyl content and oxidation limits.

◆ 01 · What a marine source changes

Marine lecithins are not a species variant of soy lecithin; they are structurally a different class of material. Fish roe from salmon, herring, pollock and flying fish holds 38–75% of its total lipids as phospholipids, with PC as the dominant class and more than 30% of all fatty acids accounted for by EPA and DHA. In krill oil, typically around 40% of the lipid mass is phospholipid, and class analysis shows PC alone reaching the high 80s as a share of that fraction. Fish muscle runs the other way — phospholipids are only 1–1.5% of tissue, yet they can carry up to a third of the fish's total EPA and DHA, which is why by-product streams with concentrated membrane material matter commercially.

Geography and diet write themselves into the profile. Published comparisons put the EPA+DHA to arachidonic+linoleic acid ratio at 14.5 for wild salmon against 1.5 for farmed fish on vegetable-oil feeds, with krill at 12.0. For formulators, the wild-caught plankton and roe streams sit in a different compositional neighbourhood from anything recovered from fed aquaculture — and the certificate confirms which one you are holding.

◆ 02 · The class composition ledger

Total phospholipid is a blunt number; the class breakdown is where sourcing decisions are actually made. Published compositions of the phospholipid fraction show how sharply the headgroup profile moves between sources:

Two practical readings fall out of this table. First, krill and roe are choline-addressed materials — if your work needs PC-dominant bilayer behaviour, that is where the leverage is. Second, squid and fish-muscle fractions bring a meaningful PE share, and PE's smaller, less hydrated headgroup shifts bilayer packing and phase behaviour in ways PC fractions cannot imitate. Lyso-PC appearing in muscle-derived fractions is a further handle: it signals membrane-origin material and also serves as the hydrolysis marker discussed in section 07.

◆ 03 • Krill oil, written the way a monograph reads it

Krill is the one marine phospholipid source with a mature pharmacopoeial definition, and it is worth quoting the shape of it because it shows what 'phospholipid-rich' means in auditable terms. The USP monograph for krill oil fixes total phospholipids at not less than 30% and not more than 59% of the oil, with 60–96% of that fraction made up of PC, 1-lyso-PC and 2-lyso-PC together; EPA not less than 10% and DHA not less than 5% of the oil, mostly bound as phospholipids; and astaxanthin at a minimum of 0.005%. Around those anchors sit the numbers buyers check first: krill PC has been calculated at roughly 34 g per 100 g of oil, the carotenoid fraction runs 878–1,016 µg/g, and the shell-derived fluoride that makes krill handling unusual is controlled by stripping the exoskeleton immediately after catch — over 99% of it lives there, which is why on-board stabilisation is part of the product story rather than a processing detail.

◆ 04 • How the fraction is built

Phospholipid enrichment is a de-oiling exercise before anything else. The industrial logic runs in two moves. Neutral lipids — the triglyceride pool — leave first, either by cold acetone precipitation or by supercritical carbon dioxide; published krill work runs SC-CO₂ at 45 °C and 25 MPa with a 22 g/min flow, and the same logic applied to salmon frame material at 45 °C and 27.5 MPa pulled out a 6.9% phospholipid yield from de-oiled bone at 80.4% purity. Then the phospholipid fraction itself comes out with ethanol — either neat or as a 30% co-solvent stage — followed by acetone washing to strip residual neutral oil. Two-step sequences of this kind reach 93–97% purity on krill residues, and tuning the co-solvent stage recovers up to 90% of the phospholipids initially present in scallop by-products.

The choice between solvent routes is a quality trade, not a yield trade. Supercritical extraction runs cool and leaves no solvent residue, and the resulting fractions show lower acid, peroxide and anisidine values than warm ethanol extracts of the same raw material; ethanol, meanwhile, is cheaper at tonnage scale and keeps a polar phase available for the phospholipid headgroups. We quote both routes and let the application decide.

◆ 05 • Reading a phospholipid certificate

Phospholipid certificates are read line by line, and the lines mean different things than they do for fish oil:

• Total phospholipids. Measured as acetone-insoluble matter or by phosphorus assay — one gram of phospholipid carries roughly 4% phosphorus, so a phosphorus reading converts directly. Crude lecithin extracts typically land at 40–70% total phospholipids, refined concentrates at 85–98%.
• PC content. Quantified by HPLC with evaporative light-scattering detection, or by ³¹P NMR for the full class picture without standards for every species. Acceptance limits move with grade: around 60% PC for standard fractions, upward of 90% for highly purified material.
• Hydrolysis markers. Lyso-PC (0.5–5% in sound material) and free fatty acids track phospholipase activity and poor temperature control upstream; a rising lyso-PC share is the first alarm in this class.
• Oxidation trio. Peroxide value, anisidine value and their TOTOX combination — peroxide values near or below 5 meq/kg and acid values below about 30 mg KOH/g are the working ceilings for sound fractions.
• Solvent and metal residues. Headspace GC for acetone and hexane, ICP for lead and arsenic, Karl Fischer for water (keep it under about 2%).

◆ 06 • Self-assembly is the application

Ask a phospholipid to meet water and it builds architecture — that behaviour, not nutrition, is why materials science keeps ordering marine fractions. Hydrate a thin lipid film and the sheets close into liposomes: single- or multi-bilayer vesicles that can carry an aqueous core or an amphiphilic cargo. Extracts that keep ethanol in the system form ethosomes instead — smaller, more fluid vesicles used in dermal delivery research. The class composition decides how well any of this works: PC-dominant fractions form stable bilayers readily, PE tightens packing and raises the transition temperature, and lyso-PC widens the curvature. Supercritical extracts from salmon and scallop by-products have been shown to self-assemble directly into liposomes without further purification — the fraction arrives already functional.

◆ 07 • The oxidation ledger, phospholipid edition

Marine phospholipids oxidise faster than the triglyceride oils they sit beside, and pretending otherwise is how bad lots happen. The same membrane architecture that makes them useful keeps their polyunsaturated chains exposed at an interface, and liposomal form accelerates oxidation further still — which is why oxidative stability of the liposomal form is itself a published research topic. Practical control has three layers: keep oxygen out (nitrogen headspace at every transfer), keep light and heat down (amber containers, chilled logistics, no open evaporations), and lean on the antioxidants the raw material already carries — krill's astaxanthin is not decorative, and tocopherol or rosemary additions are routine for fraction grades.

Watch the lyso-PC line on the certificate as closely as the peroxide line. LPC grows when phospholipase A₁/A₂ snips an acyl chain — a hydrolysis problem rather than an oxidation one, and temperature-driven rather than oxygen-driven. A lot can pass TOTOX and still have quietly hydrolysed in a warm warehouse, which is why cold-chain handling is written into how we ship these materials.

◆ 08 • Where the fractions go

◆ 09 • Fractions made to order

Source, class profile and physical form are three independent dials, and most projects need a specific combination rather than a stock list. We take on custom work across the range described here: single-source fractions from krill, roe, squid or defined by-product streams; PC enrichment by chromatography or solvent fractionation to a target class composition; de-oiled powders, fluid lecithins or ethanol-process extracts; and oxygen-controlled packing under nitrogen with the antioxidant system agreed in advance. Specification sheets are written against your measurement methods — if your lab quantifies by ³¹P NMR rather than HPLC-ELSD, the certificate says so. Tell us the headgroup profile, the acyl range and the form you need, and the fraction gets built to that brief.

For Research or Industrial Raw Materials, Not For Personal Medical Use!