Improving carboxymethyl cellulose edible coating using ZnO nanoparticles from irradiated Alternaria tenuissima

Abstract

In this paper, gamma-irradiation was successfully used to intensify the yield of Zinc oxide nanoparticles (ZnONPs) produced by the fungus Alternaria tenuissima as a sustainable and green process. The obtained data showed that 500 Gy of gamma-irradiation increased ZnONPs' yield to approximately four-fold. The synthesized ZnONPs were then exploited to develop active Carboxymethyl Cellulose films by casting method at two different concentration of ZnONPs 0.5% and 1.0%. The physicochemical, mechanical, antioxidant, and antimicrobial properties of the prepared films were evaluated. The incorporation of ZnONPs in the Carboxymethyl Cellulose films had significantly decreased solubility (from 78.31% to 66.04% and 59.72%), water vapor permeability (from 0.475 g m^-2 to 0.093 g m^-2 and 0.026 g m^-2), and oxygen transfer rate (from 24.7 × 10^-2 to 2.3 × 10^-2 and 1.8 × 10^-2) of the respective prepared films. Meanwhile, tensile strength (from 183.2 MPa to 203.34 MPa and 235.94 MPa), elongation (from 13.0% to 62.5% and 83.7%), and Yang's modulus (from 325.344 to 1410.0 and 1814.96 MPa) of these films were increased. Moreover, the antioxidant and antimicrobial activities against several human and plant pathogens the prepared of Carboxymethyl Cellulose-ZnONPs films were significantly increased. In conclusion, the prepared Carboxymethyl Cellulose-ZnONPs films showed enhanced activities in comparison with Carboxymethyl Cellulose film without NPs. With these advantages, the fabricated Carboxymethyl Cellulose-ZnONPs films in this study could be effectively utilized as protective edible coating films of food products.

Keywords: Active food packaging; Alternaria tenuissima; Carboxymethyl cellulose; Edible coating films; Gamma irradiation; Zinc oxide nanoparticles.

Fig. 1

X-ray diffraction pattern (Cu Kα-radiation) at room temperature of ZnONPs synthesized by the fungus A. tenuissima

Fig. 2

TEM analysis of ZnONPs synthesized by the fungus A. tenuissima; (A) TEM micrograph and (B) SAED pattern

Fig. 3

Particle size distribution of ZnONPs synthesized by the fungus A. tenuissima

Fig. 4

Zeta potential of ZnONPs synthesized by the fungus A. tenuissima

Fig. 5

Effect of several gamma-irradiation doses on the production of ZnONPs synthesized by the fungus A. tenuissima. All data are shown as the mean ± SD of triplicate measurements from three independent experiments

Fig. 6

DPPH free radical scavenging activity of the prepared films. Ascorbic acid was used as positive control. Calculated mean is for triplicate measurements from three independent experiments ± SD, ^a−d means with different superscripts are considered statistically different (LSD test, P ≤ 0.05)

Fig. 7

Photograph of the antibacterial and antifungal activities of the prepared films against different pathogenic bacterial strains, unicellular fungi, and plant pathogenic fungi