W/O Nano‐Emulsions with Olive Leaf Phenolics Improved Oxidative Stability of Sacha Inchi Oil

Abstract

Natural phenolic compounds have been drawn a wide attention to replace the synthesis antioxidants due to the food safety issues, while, natural phenolic compounds are usually polyhydroxy derivatives which exhibit hydrophilic capacity, limiting their applications directly in lipid systems. In this work, olive leaf phenolics (OLP) are extracted by ultrasound from five cultivars and the optimal cultivar is chosen to prepare W/O nano‐emulsions of Sacha Inchi oil (SIO, containing more than 90% polyunsaturated fatty acids). The droplet size could reach 2.15 ± 0.13 nm and remaines stable without phase separation during 30‐day storage. Oxidative stabilities of SIO containing 0.02%, 0.05%, and 0.1% OLP (w/w) are evaluated by Rancimat test and accelerated storage test. The release of OLP by preparation of W/O nano‐emulsions is capable of controlling the oxidative progress of SIO, by prolonging the induction time, preventing the production of primary and secondary oxidative products and also the deterioration of polyunsaturated fatty acids and tocopherols.Practical Applications: Sacha Inchi oil (SIO) contains approximately 90% of polyunsaturated fatty acids (PUFAs) associated with poor oxidative stability. Olive leaf phenolics (OLP) are considered as a great and cheap source of natural phenolic compounds. This study aimes to select the optimum source of OLP from five cultivars and to prepare a W/O nano‐emulsion of OLP. By diluting the W/O nano‐emulsion of OLP into SIO, effect of different concentrations OLP on the oxidative stability of SIO is evaluated through thermal oxidative stability and storage oxidative stability in an accelerated storage test. Results indicate that the capacity of OLP to retard the SIO oxidation depends on the incorporated concentration, which means that it is doable to adopt OLP, an abundant and cheap material, to improve the stability of edible oil with high PUFAs in the industry.Olive leaf phenolics are extracted and detected to prepare an efficient and stable W/O nano‐emulsion; By diluting W/O nano‐emulsion into Sacha Inchi oil, oxidative stability of the high content PUFAs oil is improved.