Nanofillers in Novel Food Packaging Systems and Their Toxicity Issues

Abstract

Background: Environmental concerns about petroleum-based plastic packaging materials and the growing demand for food have inspired researchers and the food industry to develop food packaging with better food preservation and biodegradability. Nanocomposites consisting of nanofillers, and synthetic/biopolymers can be applied to improve the physiochemical and antimicrobial properties and sustainability of food packaging. Scope and approach: This review summarized the recent advances in nanofiller and their applications in improved food packaging systems (e.g., nanoclay, carbon nanotubes), active food packaging (e.g., silver nanoparticles (Ag NPs), zinc oxide nanoparticles (ZnO NPs)), intelligent food packaging, and degradable packaging (e.g., titanium dioxide nanoparticles (e.g., TiO₂ NPs)). Additionally, the migration processes and related assessment methods for nanofillers were considered, as well as the use of nanofillers to reduce migration. The potential cytotoxicity and ecotoxicity of nanofillers were also reviewed. Key findings: The incorporation of nanofillers may increase Young's modulus (YM) while decreasing the elongation at break (EAB) (y = -1.55x + 1.38, R² = 0.128, r = -0.358, p = 0.018) and decreasing the water vapor (WVP) and oxygen permeability (OP) (y = 0.30x - 0.57, R² = 0.039, r = 0.197, p = 0.065). Meanwhile, the addition of metal-based NPs could also extend the shelf-life of food products by lowering lipid oxidation by an average of approx. 350.74% and weight loss by approx. 28.39% during the longest storage period, and significantly increasing antibacterial efficacy against S. aureus compared to the neat polymer films (p = 0.034). Moreover, the migration process of nanofillers may be negligible but still requires further research. Additionally, the ecotoxicity of nanofillers is unclear, as the final distribution of nanocomposites in the environment is unknown. Conclusions: Nanotechnology helps to overcome the challenges associated with traditional packaging materials. Strong regulatory frameworks and safety standards are needed to ensure the appropriate use of nanocomposites. There is also a need to explore how to realize the economic and technical requirements for large-scale implementation of nanocomposite technologies.

Keywords: active food packaging; degradable packaging; improved food packaging; intelligent food packaging; migration; nanofillers; toxicity.

Figure 1

Schematic representation of the use of nanofillers to improve the physiochemical properties of food packaging, which keeps apples fresh after about 10 days of storage. Created with BioRender.com.

Figure 2

Changes in (a) elongation at break (EAB) vs. Young’s modulus (YM): y = −1.55x + 1.38, R² = 0.128, r = −0.358, p = 0.018; and (b) changes in water vapor permeability (WVP) vs. oxygen permeability (OP): y = 0.30x − 0.57, R² = 0.039, r = 0.197, p = 0.065, when adding nanofillers as compared to control. These correlations are obtained from the data in Table 1. r: Pearson correlation coefficient; R²: Coefficient of determination. The orange line is the regression line.

Figure 3

Mechanisms of antimicrobial activities of metal NPs. (1) Cell wall penetration; (2) the inhibition of cell wall synthesis; (3) the inhibition of DNA replication; (4) collapse of cell membrane potential and electron transport with a decrease in ATP. Created with BioRender.com.

Figure 4

(A) Comparison of NP films and NP-free films for shelf-life extension applications, where shelf-life is indicated by lipid oxidation and weight loss. (B). Comparison of antimicrobial activity of NP films and NP-free films against Gram-negative A. niger and E. coli, and Gram-positive L. monocytogenes and S. aureus. The column indicates average changes in control film values and optimal film values for each parameter during the longest storage period, expressed as mean ± standard error. *: p < 0.05 between NP and NP-free film.

Figure 5

Commercial application of indicators in intelligent packaging systems. (a) Time and temperature indicators (TTI); (b). freshness indicators; (c) pH sensors; (d). RFID. Created with BioRender.com.

Figure 6

Exposure routes, translocation distribution, and excretion pathways of nanofillers in the human body. Created with BioRender.com.