Abstract
Objectives
Eucommia ulmoides Oliver seed oil (E.u oil) as a natural product is particularly rich in α-linolenic acid (56–63%) and vitamin E. The aim of this study was to prevent the premature oxidation and improve bioavailability and environmental resistance of E.u oil in food industry. A novel biocompatible inverse E.u oil microemulsion (ME) was developed using food grade ingredients and was able to incorporate tea polyphenols (TPs), a natural food antioxidant.
Methods
The MEs were formulated using E.u oil, water, a blend of Sorbitan monooleate 80 and Polysorbate 80, propylene glycol, and TPs. Pseudo-ternary diagrams were built to illustrate the phase behavior of the MEs. Structural and activity aspects of empty and TPs-loaded systems were studied using various techniques such as Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), Infrared Spectroscopy (IR), and Electron Paramagnetic Resonance (EPR). Rheological characterization and preliminary and accelerated stability tests were performed.
Results
The empty and TPs-loaded MEs showed a Newtonian profile, and had linear viscosity, good tolerance to pH and salinity. Those MEs with narrow size distribution, nanoscale particle size (below 50 nm), transparent appearance had a wide range of oil phase content. IR studies indicated that TPs were successfully encapsulated in the aqueous cores of the MEs. Within 63 days of accelerated oxidation at 65°C, the peroxide value of E.u oil increased from 0.89 to 49.66 meq O2/kg oil, and the TPs-loaded ME increased from 0.37 to 21.00 meq O2/kg oil, revealing that TPs-loaded ME could slow down the oxidation of oil. Finally, EPR results demonstrated that the encapsulated TPs showed the higher antioxidant activity than empty ME.
Conclusions
This nanostructure, environmental stability and antioxidant activity of TPs-loaded ME containing E.u oil is a potential delivery system as an alternative to α-linolenic acid and benefit for the protection and wider application of E.u oil.
Funding Sources
The authors gratefully acknowledge the support of this work by Project supported by the Key R&D Project of Science and Technology Development of Hunan Province of China (2018NK2045), the National & Local United Engineering Laboratory of Integrative Utilization Technology of Eucommia ulmoides (NLE201702) and Graduate Research Project of JiShou University (JDY1843).
Formation and Oxidation Stability of Tea Polyphenols-Loaded W/O Microemulsion with Eucommia Ulmoides Oliver Seed Oil as an Alternative to α-linolenic Acid