Development and Characterization of Chitosan and Porphyran Based Composite Edible Films Containing Ginger Essential Oil

Abstract

Recent research shows the growing interest in the development of composite edible films (EFs) by using multiple biopolymers for the substantial improvement in the shelf life and quality of food products, via preventing oxidation among other benefits. In the present work, EFs based on chitosan (CS) and porphyran (POR) loaded with ginger essential oil (GEO) have been developed to study the effect of GEO, glycerol (Gly), and POR on the film structure as well as physical and antioxidant properties. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results showed the level of crystallinity and electrostatic interactions between CS, POR, Gly, and GEO. It was found that electrostatic interactions between CS and POR and the incorporation of GEO substantially improved barrier, thermal, optical, and mechanical properties and reduced the moisture content, swelling index, and thickness values. The color values of the S5 film altered apparently with a shift towards yellowness. SEM micrographs of the composite CS-POR-GEO film (S5) showed improved morphological attributes such as more uniformity and homogeneous structure than other films (S1-S4). Results obtained from total phenolic content assay suggested the presence of high phenolic components (5.97 ± 0.01) mg of GAE/g in GEO. Further, findings obtained from antioxidant assays revealed that the addition of GEO and POR significantly increased the antioxidant effects of CS films. All these findings suggested that GEO loaded CS-POR based films showed better physical and chemical properties with a significant improvement in antioxidant potential and thus can be used as a potential packaging material in the food industry.

Keywords: antioxidant; chitosan; composites; edible films; food packaging; ginger essential oil; glycerol; porphyran.

Figure 1

Polyelectrolyte complex (PEC) formation between chitosan (CS) and porphyran (POR) under the specified experimental conditions (pH 3.9).

Figure 2

Visual appearances of CS blank film (S1), CS-Gly film (S2), CS-S-GEO film (S3), CS-POR-Gly film (S4), and CS-POR-Gly-GEO film (S5); yellow arrows indicate film crumble into pieces during peeling process; blue arrow represents more force was required for peeling; white arrows represent films were not broken into pieces during peeling; red arrow represents less force required for peeling.

Figure 3

Thermogravimetric curves of CS blank film (S1), CS-Gly film (S2), CS-Gly-GEO film (S3), CS-POR-Gly film (S4), and CS-POR-Gly-GEO film (S5).

Figure 4

XRD patterns of CS blank film (S1), CS-Gly film (S2), CS-Gly-GEO film (S3), CS-POR-Gly (S4), and CS-POR-Gly-GEO film (S5).

Figure 5

SEM images of CS blank film (S1), CS-Gly film (S2), CS-Gly-GEO film (S3), CS-POR-Gly film (S4), and CS-POR-Gly-GEO film (S5) (superior and cross section view); yellow arrows represent particles over the surface; purple colour arrows indicate compact, uniform, homogenous, and dense structure; green colour represents bulges over the surface and roughness; white arrows represent porosity and irregularity in the film; and blue arrows represents the cracks over the surface and cross-section.

Figure 6

FTIR spectra of CS blank film (S1), CS-Gly film (S2), CS-Gly-GEO film (S3), CS-POR-Gly film (S4), and CS-POR-Gly-GEO film (S5).

Figure 7

Antioxidant capacity of CS blank film (S1), CS-Gly film (S2), CS-S-GEO film (S3), CS-POR-Gly film (S4), CS-POR-Gly-GEO film (S5), butylated hydroxyl anisole (S6) determined by DPPH assays. Bars represent mean values ± standard deviations. Bar with different letters (a, b & c) shows significant difference among the groups (p < 0.05).

Figure 8

Antioxidant potential of CS blank film (S1), CS-Gly film (S2), CS-S-GEO film (S3), CS-POR-Gly film (S4), CS-POR-Gly-GEO film (S5) and Trolox (S6) determined by TEAC assay. Bars represent mean values ± standard deviations. Bar with different letters (a, b & c) shows significant difference among the groups (p < 0.05).