Encapsulation of Cinnamon Essential Oil for Active Food Packaging Film with Synergistic Antimicrobial Activity

Abstract

Porous adsorption, a less powerful adsorptive force than chemical bonds, is based on the physical adsorption of small molecules onto a solid surface that is capable of adsorbing gas or liquid molecules. Antimicrobial permutite composite (containing Ag⁺, Zn²⁺ and Ag⁺/Zn²⁺), starting from Linde Type A-permutite (LTA), was obtained in this research. The permutite samples were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), colorimeter and nitrogen adsorption technique. Cinnamon essential oil (CEO) was encapsulated into Ag⁺/Zn²⁺-permutite. The FT-IR and differential scanning calorimetry (DSC) confirmed that no chemical bond existed between CEO and Ag⁺/Zn²⁺-permutite. The loading capacity of Ag⁺/Zn²⁺-permutite/CEO was 313.07 µL/g, and it had a sustained release effect. The Ag⁺/Zn²⁺-permutite/CEO showed stronger efficacy against Aspergillusniger and Penicillium sp. than Ag⁺/Zn²⁺-permutite. Ethyl cellulose pads modified by composite antimicrobial particles were applied in the preservation of Chinese bayberry. Compared to the control group, treatment with the Ag⁺/Zn²⁺-permutite/CEO antimicrobial pads resulted in a significantly lower decay incidence. In addition, the amount of migrated silver, zinc and aluminum from LTA was below the legal limit. These results confirmed that the ethyl cellulose pads modified by the Ag⁺/Zn²⁺-permutite/CEO provided an active packaging to control decay of fresh Chinese bayberry.

Keywords: antimicrobial; bayberry fruit; cinnamon essential oil; nano-porous materials.

Figure 1

Chemical structure of cinnamaldehyde.

Figure 2

SEM images (A) and XRD spectra (B) of permutite with different treatments; (a) Untreated, (b) 0.1 mol Ag⁺, (c) 0.1 mol Zn²⁺, (d) 0.1 mol Ag⁺ and 0.1 mol Zn²⁺; Nitrogen sorption isotherms of permutite samples; (C) permutite, (D) Ag⁺/Zn²⁺-permutite.

Figure 2

SEM images (A) and XRD spectra (B) of permutite with different treatments; (a) Untreated, (b) 0.1 mol Ag⁺, (c) 0.1 mol Zn²⁺, (d) 0.1 mol Ag⁺ and 0.1 mol Zn²⁺; Nitrogen sorption isotherms of permutite samples; (C) permutite, (D) Ag⁺/Zn²⁺-permutite.

Figure 2

SEM images (A) and XRD spectra (B) of permutite with different treatments; (a) Untreated, (b) 0.1 mol Ag⁺, (c) 0.1 mol Zn²⁺, (d) 0.1 mol Ag⁺ and 0.1 mol Zn²⁺; Nitrogen sorption isotherms of permutite samples; (C) permutite, (D) Ag⁺/Zn²⁺-permutite.

Figure 3

FTIR spectra (A) of ion-exchanged permutite: (a) permutite, (b) Ag⁺-permutite, (c) Ag⁺/Zn²⁺-permutite, (d) Zn²⁺-permutite; FTIR spectra (B) of Ag⁺/Zn²⁺-permutite/CEO; DSC curve (C) of permutite samples.

Figure 4

Standard curve (A) of cinnamon essential oil ethanol solution; the release profiles of CEO (B) and Ag⁺/Zn²⁺-permutite/CEO (C) storage at different temperatures (4 °C, 15 °C, 25 °C).

Figure 4

Standard curve (A) of cinnamon essential oil ethanol solution; the release profiles of CEO (B) and Ag⁺/Zn²⁺-permutite/CEO (C) storage at different temperatures (4 °C, 15 °C, 25 °C).

Figure 5

SEM images of antimicrobial pads, (a) Absorbent pads (surface), (b) The ethyl cellulose pads (surface), (c) The ethyl cellulose pads modified by permutite (surface), (d) The ethyl cellulose pads modified by Ag⁺/Zn²⁺-permutite (surface), (e) The ethyl cellulose pads modified by Ag⁺/Zn²⁺-permutite (surface), (f) The ethyl cellulose pads modified by Ag⁺/Zn²⁺-permutite (cross-sectional).

Figure 6

Antimicrobial activity assays against (A) Aspergillus niger and (B) Penicillium.

Figure 7

Chinese bayberry fruit at different storage times with different treatments (A); Total soluble solids (B) and Decay rate (C) of Chinese bayberry fruit packaged with different pads; a: The ethyl cellulose pads, as control, b: The ethyl cellulose pads modified by permutite, c: The ethyl cellulose pads modified by Ag⁺/Zn²⁺-permutite, d: The ethyl cellulose pads modified by A^g+/Zn²⁺-permutite/CEO; * means significantly different at p < 0.05 level.