Physical and chemical stability of anthocyanin-rich black carrot extract-loaded liposomes during storage

In this study, the protection effect of black carrot extract on the stability of liposomes during storage was evaluated. The physical and chemical stability of the extract (0.4% w/w) including extract-loaded liposomes with various lecithin content (1%, 2%, and 4% w/w) were demonstrated. Z-average particle diameter and zeta potentials of liposomes were evaluated before and after 21 days of storage. The particle diameter of the samples was found to be lower than 50 nm after storage and no statistical change was determined (p < 0.05). The liposomes with and without extract were visualized by transmission electron microscopy (TEM) after negative staining. The TEM images revealed that unloaded and extract-loaded liposomes are similar in size. The degradation of extract (30%-90%), phenolic content (10%-29%), and antioxidant capacity (4%-33%) of liposomes depending on lecithin content were also determined during storage to evaluate the biochemical stability. A hexanal analysis was performed to investigate the lipid oxidation in liposomes within 60 days. According to the results, the oxidation of polyunsaturated fatty acids may be inhibited with the addition of the extract to liposomes; however, lipid content should be limited according to the extract concentration. The highest protection on oxidation was observed in extract-loaded liposomes containing 1% lecithin. The study provided valuable data on the contribution of an anthocyanin addition to liposomes to overcome oxidation of unsaturated phospholipids.