Evaluation of the Antioxidant and Antimicrobial Potential of SiO2 Modified with Cinnamon Essential Oil (Cinnamomum Verum) for Its Use as a Nanofiller in Active Packaging PLA Films

Abstract

One of the main causes of food spoilage is the lipid oxidation of its components, which generates the loss of nutrients and color, together with the invasion of pathogenic microorganisms. In order to minimize these effects, active packaging has played an important role in preservation in recent years. Therefore, in the present study, an active packaging film was developed using polylactic acid (PLA) and silicon dioxide (SiO2) nanoparticles (NPs) (0.1% w/w) chemically modified with cinnamon essential oil (CEO). For the modification of the NPs, two methods (M1 and M2) were tested, and their effects on the chemical, mechanical, and physical properties of the polymer matrix were evaluated. The results showed that CEO conferred to SiO2 NPs had a high percentage of 2,2-diphenyl-l-picrylhydrazyl (DPPH) free radical inhibition (>70%), cell viability (>80%), and strong inhibition to E. coli, at 45 and 11 µg/mL for M1 and M2, respectively, and thermal stability. Films were prepared with these NPs, and characterizations and evaluations on apple storage were performed for 21 days. The results show that the films with pristine SiO2 improved tensile strength (28.06 MPa), as well as Young’s modulus (0.368 MPa) since PLA films only presented values of 27.06 MPa and 0.324 MPa, respectively; however, films with modified NPs decreased tensile strength values (26.22 and 25.13 MPa), but increased elongation at break (from 5.05% to 10.32–8.32%). The water solubility decreased from 15% to 6–8% for the films with NPs, as well as the contact angle, from 90.21° to 73° for the M2 film. The water vapor permeability increased for the M2 film, presenting a value of 9.50 × 10−8 g Pa−1 h−1 m−2. FTIR analysis indicated that the addition of NPs with and without CEO did not modify the molecular structure of pure PLA; however, DSC analysis indicated that the crystallinity of the films was improved. The packaging prepared with M1 (without Tween 80) showed good results at the end of storage: lower values in color difference (5.59), organic acid degradation (0.042), weight loss (24.24%), and pH (4.02), making CEO-SiO2 a good component to produce active packaging.

Smart Packaging Based on Polylactic Acid: The Effects of Antibacterial and Antioxidant Agents from Natural Extracts on Physical–Mechanical Properties, Colony Reduction, Perishable Food Shelf Life, and Future Prospective

“…The tensile strength of the resulting film also decreases due to the plasticizing effect of essential oils. Essential oils are highly hydrophobic, so they affect the hydrophilic/hydrophobic balance of the film [50,51]. Based on the previous works, it can be concluded that the tensile properties of PLA smart packaging are influenced by the amount of active agent, type of active agent, and specific formulation of the PLA blend.…”

Effect of Nano-Silica and Sorbitol on the Properties of Chitosan-Based Composite Films

“…When water droplets come into contact with the film, they quickly diffuse due to the attraction of hydroxyl groups [57,71]. Martínez-Aguilar et al [72] added nano-SiO 2 to a PLA film, observing that the WCA of the film decreased. Yu et al [71] constructed a superhydrophilic surface with nano-SiO 2 on chitosan film; the WCA of the film decreased from 66.1 • to 3 • .…”