Conclusions
In this study, hexane extraction of Osage orange fruit produced an extract rich in osajin (42.9%) and pomiferin (30.0%). The antioxidant activity of the extract (OOE) was examined in stripped SBO and FO at 0.1 wt.% during storage at 25 and 40 ℃ using PV, CDV and p -AV. The overall antioxidant activity order was BHT ≈ OOE > RE > Toco in SBO at 25 ℃ and 40 ℃. In contrast, the activity order was OOE ≥ BHT > Toco > RE in FO at both temperatures, 25 ℃ and 40 ℃. The activities of 0.05, 0.1 and 0.2% OOE in SBO were not very different indicating that the protection of SBO from oxidation can be achieved at a concentration of OOE as low as 0.05%. Unlike in SBO, the antioxidant activity of OOE increased with increasing concentration from 0.05% to 0.2% in FO. Headspace volatile oxidation products were analyzed using SPME combined with GC-MS. 0.1% OOE was effective in preventing the formation of volatile oxidation products in SBO and FO. While all four antioxidants had similar effects in SBO, 0.1% OOE prevented the formation of volatile oxidation products better than 0.1% RE and similar to 0.02% BHT and 0.1% Toco in FO. Although it should be further tested for safety before the actual use, the strong antioxidant activity of OOE in SBO and FO found in this study indicates the high potential of OOE as a natural antioxidant for edible oils and oil-containing food products.