Production and encapsulation of eicosapentaenoic acid (EPA)‑rich lipid extract from Phaeodactylum tricornutum under different cultivation conditions.

The microalga Phaeodactylum tricornutum is a promising microalgal source of the omega-3 fatty acid eicosapentaenoic acid (EPA). This study investigated the effects of indole-3-acetic acid (IAA), temperature, and photoperiod on biomass production, lipid accumulation, and EPA productivity of P. tricornutum, and assessed the physicochemical properties, oxidative stability, and in vitro digestion of the encapsulated lipid extract. P. tricornutum was cultured in F/2 medium until the end of the log phase. A 23 factorial design was employed with IAA (0 and 5 ppm), temperature (15 °C and 20 °C), and photoperiod (16:8 h: h and 24:0 h: h) as factors, and the response variables were biomass, lipid production, and EPA productivity. The highest EPA yield (37.90 ± 3.91 mg EPA/g biomass) was obtained under cold stress (15 °C) with IAA supplementation (5 ppm) under continuous light. The lipid extract was encapsulated in calcium alginate to improve oxidative stability and to evaluate omega-3 bioaccessibility in vitro. Encapsulation efficiency reached 89.68 ± 2.23%, and the encapsulated oils exhibited significantly lower TBARS values after 8 weeks of storage, possibly due to co-extracted pigments. In vitro digestion revealed that encapsulation protected EPA during the gastric phase and enabled its recovery during the intestinal phase. These findings highlight the potential of P. tricornutum cultivation strategies to develop stable microalgae‑derived lipid systems for functional food applications.