Characterization of tea saponins in camellia seed oil and their antioxidant behaviors: Exploration of efficient antioxidant pathway with natural surfactants in bulk oil

Tea saponins are widely known as natural surfactants while little attention has been paid to their presence in camellia seed oil. This work aimed to investigate tea saponins and their antioxidant dynamics in camellia seed oil comparing with polyphenols. First, 21 saponins belonging to five sapogenin types were characterized in camellia seed oil with UHPLC-QTOF-MS technology and camelliagenin B type accounted for above 60% of the total content. Next, the glycerides, saponins and polyphenols in the four oil samples were analyzed with mass spectrometry-based platform during 24 h accelerated oxidation after the extracts of tea saponins were added to refined camellia seed oil (RCSO) and blank camellia seed oil (BCSO), respectively. The compositional comparison showed that tea saponins slowed degradation of triglycerides with higher efficiency than both free and bound polyphenols through total decomposition during 4 h oxidation. Further, the oxidative stability of diglycerides showed that curves of RCSO and BCSO overlapped while the saponins added improved the oil samples almost uniformly, which could be related to their surficial activity resulting in a closer space proximity at the interface of “association colloids”. Overall, this study explored a novel antioxidant pathway with natural surfactants in bulk oil. • Twenty-one saponins in camellia seed oil were characterized with UHPLC-QTOF-MS. • The saponins efficiently improved the oxidative stability of glycerides. • The oxidation dynamics of diglycerides was closely modulated by the saponins. • The surficial activity might account for distinctive antioxidant pathway of saponins.