W/O Nano-Emulsions with Olive Leaf Phenolics Improved Oxidative Stability of Sacha Inchi Oil Lingyi Liu, Zhou Jin, Min Wang, Wangyang Shen, Zhenzhou Zhu, Zhan Wang, and Lianliang Liu* 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 remains 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. 1. Introduction Olive leaf could be considered as a great and cheap source of natural phenolic compounds and their extracts were revealed to enhance the oxidative instability of vegetable oils. Abundant phenolic com- pounds as tyrosol, hydroxybenzoic acid, cinnamic acid, hydroxytyrosol, caffeic acid, syringic acid, chlorogenic acid, oleuropein, among many others, could be extracted from olive leaf. [1] Nevertheless, natural phenolic compounds are usually polyhy- droxy derivatives which exhibit hydrophilic capacity, limiting their applications directly in lipid systems. Nano-emulsion technol- ogy of poorly oil-soluble bioactives has attracted wide attention in the food indus- try for increasing their distributions in oil substrates. Nano-encapsulation of bioac- tive compounds by nonionic emulsifiers and through W/O nano-emulsions could not only increase the distribution in lipids but also protect their properties (antioxi- dant, stability and solubility, etc.). [2] Nano- particles of phenolics (1–100 nm) are produced in a continuous phase and were documented to exhibit a pronounced effect on the antioxidant activity, such as green tea polyphenols and resveratrol. [3] In the study of Mohammadi et al. [4] nano-emul- sions containing olive leaf phenolics (OLP) were prepared to prevent the oxidation of soybean oil and the average dispersed Dr. L. Liu, Z. Jin, M. Wang, Dr. W. Shen, Dr. Z. Zhu, Dr. Z. Wang College of Food Science and Engineering Wuhan Polytechnic University Wuhan 430023, Hubei, P.R. China Dr. L. Liu, Dr. W. Shen, Dr. Z. Zhu, Dr. Z. Wang Key Laboratory for Deep Processing of Major Grain and Oil Ministry of Education Wuhan Polytechnic University Wuhan 430023, Hubei, P.R. China The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/ejlt.201700471. DOI: 10.1002/ejlt.201700471 Dr. L. Liu Key Laboratory of Applied Marine Biotechnology (Ministry of Education) School of marine sciences Ningbo University Ningbo 315211, Zhejiang, P.R. China E-mail: liulianliang@nbu.edu.cn Oxidative Stability www.ejlst.com RESEARCH ARTICLE Eur. J. Lipid Sci. Technol. 2018, 1700471 © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1700471 (1 of 8)