Synthesis, Controlled Release, and Stability on Storage of Chitosan-Thyme Essential Oil Nanocapsules for Food Applications.

Ricardo M González-Reza,María L Zambrano-Zaragoza,Liliana Alamilla-Beltrán,David Quintanar-Guerrero,Humberto Hernández-Sánchez,Yair Cruz-Narváez

doi:10.3390/gels7040212

Abstract

The nanoencapsulation of thyme essential oil has been greatly important in food science, given its remarkable antioxidant and antimicrobial capacity. However, its analysis in storage has not been established in terms of physical stability, antioxidant capacity, and release studies. In this paper, chitosan-thyme oil nanocapsules were prepared by the ionic gelation method. These were characterized for differential calorimetry, release kinetic, and infrared spectroscopy. The chitosan-thyme oil nanocapsules were stored at 4 and 25 °C for 5 weeks, the changes in particle size, zeta potential, stability (diffuse reflectance), and antioxidant capacity were analyzed and associated with nanocapsules’ functionality. The results show that the storage time and temperature significantly modify the particle size (keeping the nano-size throughout the storage), the release of the bioactive was Fickian with t0.193 according to Korsmery & Peppas and best described by Higuchi model associated with changes in the zeta potential from 8 mV to −11 mV at 4 °C. The differential scanning calorimetry and infrared spectroscopy results confirm the good integration of the components. The antioxidant capacity revealed a direct relationship with residual oil concentration with a decrease in the ABTS test of 15% at 4 °C and 37% at 25 °C. The residual bioactive content was 77% at 4 °C and 62% at 25 °C, confirming nanoencapsulation effectiveness. The present investigation provides helpful information so that these systems can be applied in food conservation.

Highlights

Nanotechnology is one new technology that has emerged to impact food science. This approach focuses on designing, characterizing, producing, and applying systems and components of submicron size (1 nm = 1 × 10−9 m) to form substances or materials with specific, desirable properties [1]
The infrared spectroscopy and differential scanning calorimetry characterization revealed the excellent integration of components in the nanocapsules of thyme essential oil, and scanning electron microscopy evidenced nanocapsule spherical structure
The nanocapsules of thyme essential oil prepared by ionic gelation showed good stability to storage after 5 weeks of storage at 4 and 25 ◦ C, the lower residual content of thyme essential oil was at 25 ◦ C

Summary

Introduction

Nanotechnology is one new technology that has emerged to impact food science. This approach focuses on designing, characterizing, producing, and applying systems and components of submicron size (1 nm = 1 × 10−9 m) to form substances or materials with specific, desirable properties [1]. Nanocapsules (NC) are vesicular systems made of polymeric membrane or wall, in which the active molecules are encapsulated [3]. The wall polymer should be preferer of natural origin with the advantage of having the best compatibility with food components, and to have the functionality desired in the system, consider the polymer compatibility with the compound to be transported [5]

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Conclusion