Molecular distillation of sea buckthorn pulp oil: Enhanced removal and distribution analysis of Phthalic acid esters

Sea buckthorn (Hippophae rhamnoides L. ) pulp oil (SPO) is valued for its bioactive compounds but often contaminated by phthalic acid esters (PAEs), posing health risks. Herein, molecular distillation under optimized response-surface conditions (164 °C distillation temperature, 150 r/min scraper speed, 15 mL/min feed rate) removed 92.3% of PAEs, reducing diisobutyl phthalate (DIBP), di-n-butyl phthalate (DBP), and di-(2-ethylhexyl) phthalate (DEHP) concentrations to 0.018, 0.024, and 0.634 mg/kg, respectively. Comparative investigations revealed that distillation temperature was the dominant factor influencing PAE elimination and carotenoid preservation. The phase migration and distribution of PAEs were analyzed, thereby excluding the possibility of chemical conversion during molecular distillation. Specifically, 83.6% of DBP remained in the molecular distillation apparatus or was removed by the pump, while 38.5% of DIBP and 47.0% of DEHP were concentrated in the light phase through condensation. Fatty acid profiles, including palmitoleic acid content, remained unchanged with no trans -fatty acids detected. These findings could support the development of high-quality SPO production in industrial applications. • 92.30% removal of phthalic acid esters (PAEs) from sea buckthorn pulp oil (SPO). • Temperature significantly affects PAE removal and carotenoid retention. • Phase migration analysis excluded chemical conversion of PAEs during process. • No change in fatty acid composition or trans-fatty acids during process.