Comprehensive chemical profiling of fluid sunflower lecithin reveals a complex matrix beyond phospholipids

Sunflower lecithin is a food ingredient obtained as a by-product of sunflower oil refining; however, its chemical complexity and functional properties, particularly in fluid (non-deoiled) form, remain poorly characterized. In this study, sunflower fluid lecithin (SFL) produced at industrial scale was investigated through an integrated approach combining physicochemical quality assessment, compositional analysis, profiling of unsaponifiable matter and minor bioactive compounds, antioxidant activity evaluation, and safety verification. SFL complied with regulatory specifications for food-grade phosphatide concentrates, showing low moisture and insoluble matter contents together with acceptable oxidative and hydrolytic stability. Compositional analysis revealed phospholipids as main components, associated with neutral lipids, proteins, carbohydrates, and mineral residues. UPLC-QTOF-MS profiling detected phenolic acid derivatives, including caffeoylquinic compounds, while spectrophotometric assays confirmed measurable total phenolic and flavonoid contents (10.73 mg GAE/g and 0.85 mg RE/g, respectively). The unsaponifiable fraction contained minor lipophilic compounds such as tocopherols and photosynthetic pigments, retained due to mild processing conditions during lecithin recovery. In vitro functional analysis revealed broad-spectrum antioxidant activity, including radical scavenging (DPPH 12.99 mg TE/g; ABTS 16.60 mg TE/g), reducing capacity (CUPRAC 32.25 mg TE/g), and metal-chelating activity. Overall, results highlight the chemical and functional complexity of SFL, supporting its role as a multifunctional ingredient and promoting the sustainable valorization of oil-refining by-products in food production.