Lecithins are commercial-grade mixtures of glycerophospholipids recovered as a by-product of vegetable-oil refining and are dominated by phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidic acid (PA), and minor lysophospholipids (LPC, LPE) [1,2]. The phosphate-bearing head group on a 1,2-diacyl-sn-glycerol backbone confers amphiphilicity, hydrogen-bonding capacity at the oil-water interface, and affinity for lipophilic micronutrients—properties that underlie lecithin use food emulsifier, liposomal carrier, and nutraceutical (Figure 1) [2,3]. Recoverable lecithin yield differs roughly tenfold between sources, which decides whether an oil is a viable commercial feedstock or only a specialty one.

In the seed itself, PLs play a structural rather than a storage role—they form the monolayer that coats oil bodies (oleosomes) and surrounds organellar membranes, while triacylglycerols (TAGs) accumulate inside oil bodies as the energy store mobilized on germination [4,5]. Lipidomic profiling of Cannabis sativa has confirmed this division; in developing hemp seeds PC accounts for 30.6% of the total lipid pool but in root tissue the same class reaches 40.4% of total lipids, with PA additionally rising to 21.9%—reflecting the contrasting biosynthetic priorities of storage versus active membrane [6]. In the oleosomes (plant oil bodies) the triacylglycerol (TAG) hydrophobic core (Figure 2—yellow) is surrounded by a phospholipid hemimembrane in which the polar head groups (Figure 2—blue) face outward and the acyl chains (Figure 2—gray blue) extend inward toward the TAG core. Two surface-associated protein families are fused in the monolayer: oleosins (Figure 2—green), which adopt a hairpin topology with a c.a. 70-residue membrane-spanning α-helix flanked by N- and C-terminal hydrophilic domains, and steroleosins (Figure 2—red), which carry a sterol-binding NADPH-reductase domain on the cytoplasmic face. Negative signs in the outer halo indicate net negative surface charge at neutral pH, arising from the phosphate head groups and the surface protein carboxylates.

Soybean lecithin currently supplies most of the world market (65–75% of total PL in deoiled products), but soy allergenicity, the predominantly GM origin of the soybean supply, and the demand for clean-label ingredients are driving interest in alternative plant lecithins [2,7]. The six oils examined here cover the principal alternatives—hemp and flax for their omega-3-rich PL fractions; sunflower as the established non-GM lecithin source with industrial-scale processing infrastructure [8]; corn germ as a high-volume by-product of dry milling [9,10]; pumpkin (particularly Cucurbita pepo var. styriaca) as a specialty oil with the highest reported PL content among the six [11,12]; and camelina as the emerging Brassicaceae oilseed amenable to genetic engineering for long-chain PUFA accumulation [5,13,14].

The allergenicity of an edible oil or its lecithin is protein-mediated rather than lipid-mediated: it arises from residual seed storage and defense proteins (for soy, the Gly m group of allergens) that are co-extracted with the lipid, not from the triacylglycerol or phospholipid fractions themselves. Fully refined oils are largely deproteinated and are generally tolerated even by sensitized individuals, whereas cold-pressed and unrefined oils and crude lecithins recovered at the degumming stage retain more residual protein and therefore greater allergenic potential [2,7,8].

Therefore two consequences follow for lecithin sourcing: 1—the demand for ‘non-allergenic’ emulsifiers is, in practice, a demand for sources outside the major regulated allergen groups and for processing that minimizes protein carry-over; and 2—among the alternatives, sunflower and canola are valued specifically as non-GM, allergen-free, clean-label sources.

This review discusses the quantitative PL data available for these six oils and links composition to processing (cold pressing, supercritical CO₂, microwave pretreatment, aqueous enzymatic extraction), refining (water, acid, enzymatic degumming, bleaching), and functional behavior (emulsion stability, oxidative kinetics, sn-2 positional fatty acid distribution), compiling (1) the botanical and gross seed-composition baseline, (2) the quantitative PL composition, and (3) the principal processing parameters and their effect on the PL fraction.

The six oilseeds chosen—hemp, sunflower, corn, pumpkin, flax and camelina—together represent the principal non-soy plant sources from which alternative lecithins can be recovered at industrial scale or in specialty markets. Being the most frequently occurring niche oils, they come from six distinct plant families and four geographic-evolutionary origins, ranging from the temperate-Eurasian Cannabis sativa, Linum usitatissimum and Camelina sativa to the American-domesticated Helianthus annuus, Zea mays and Cucurbita spp. (Figure 3). This phylogenetic and biogeographic diversity translates directly into the marked differences in oil content, protein content and dominant fatty acid profile summarized in Table 1.

The botanical background strongly impacts oil and protein content and the dominant fatty acid profile (Table 1). Their phylogenetic spread—Cannabaceae (hemp), Asteraceae (sunflower), Poaceae (corn), Cucurbitaceae (pumpkin), Linaceae (flax), and Brassicaceae (camelina)—drives a corresponding heterogeneity in oil-body architecture, PL biosynthesis, and storage-lipid composition.

Hemp seeds typically contain 25–35% lipids with linoleic acid (LA, 18:2 n-6) consistently above 50% of total fatty acids and α-linolenic acid (ALA, 18:3 n-3) at 16–20%, giving a near-ideal n-6/n-3 ratio of 2.5–3.4 [6,15]. Sunflower seeds contain 38–50% oil; the standard linoleic-type cultivars carry 55–70% LA, while high-oleic NuSun-type cultivars exceed 80% oleic acid and the high-stearic types accumulate up to 25% stearic acid, with corresponding consequences for PL acyl composition [1,8]. Maize germ—the embryo-rich fraction separated during wet or dry milling—contains 40–55% oil rich in LA (50–60%) and oleic acid (25–35%); the germ is the principal source of corn-oil PL, while pericarp and endosperm contain quantitatively distinct PL class distributions [9].

Pumpkin seeds (Cucurbita pepo L., C. maxima Duch., C. moschata Duch.) contain 40–54% oil; cold-pressed C. pepo var. styriaca (Styrian) oil shows ΣPUFA of 53.6–53.7% (predominantly LA), ΣMUFA 24–33% (oleic acid), and ALA generally < 0.5% [11,12,16,17]. Flax accumulates 35–45% oil with 35–55% ALA and an n-6/n-3 ratio close to 1:3—the highest land-plant ALA content among common oilseeds and the driver of flax PL’s unique fatty acid signature [3,18]. Camelina contains 27–49% oil and 24–31% protein; the standard cultivar profile is ALA 30–40%, oleic 15–20%, LA 15–20%, and the genus-specific 11-eicosenoic (20:1) and erucic (22:1) acids at 13–15% combined [5,19]. CRISPR-Cas9 inactivation of the FAE1 elongase locus raised seed ALA from 36.9% (wild type) to 47.3% (fae1), while the DHA1×fae1 line carrying transgenic algal desaturases/elongases accumulated 33.0% total C20⁺ n-3 fatty acids—a level comparable with refined marine oils [14].

Taken together, the six seeds converge on a broadly similar oil content (≈25–55% w/w) but diverge sharply in dominant fatty acid, splitting into an LA-dominated group (hemp, sunflower, corn, pumpkin) and an ALA-dominated group (flax, camelina)—a divergence that propagates directly into their phospholipid acyl signatures.