Stability of Sea Buckthorn, Blackcurrant, Linseed and Olive Oil-In-Water Emulsions against Thermally Induced Oxidation

Polyunsaturated lipids are recognized for their health benefit, but their application in food products is often restricted due to their high susceptibility to oxidative degradation. This study investigates how natural oil constituents affect oxidative stability in an oil-in-water emulsion model, focusing on carotenoids (HPLC/PDA), tocopherols (NP-HPLC/FL), and fatty acid profiles (GC/MS). Emulsions obtained from blackcurrant, sea buckthorn, linseed, and extra virgin olive oil by probe ultrasonication were subjected to AAPH-induced thermal oxidation, with TBARs, hexanal, and conjugated dienes monitored using UV–VIS and ITEX-GC/MS techniques. Blackcurrant oil, being highest in tocochromanols, exhibited minimal PUFA loss after heating, while linseed oil had the greatest PUFA depletion and largests increase (37%) in conjugated dienes. Linseed oil also showed a 74-fold rise in hexanal, compared to only an 8-fold increase in sea buckthorn oil, the richest in carotenoids. The production of oxidative markers inversely correlated with carotenoid and α-tocopherol content, supporting the protective, antioxidative role of these compounds. Our findings underscore the potential to improve food product stability and functionality by selecting plant oils rich in natural antioxidants. This research offers a novel comparative assessment of under-evaluated plant oils, providing valuable guidance for the development of health-promoting and stable oil-in-water emulsions for food applications.