Evaluation of bioactive low-density polyethylene (LDPE) nanocomposite films in combined treatment with irradiation on strawberry shelf-life extension

Authors: BEGUM, T - Institut National De La Recherche Scientifique (INRS); Follett, Peter; SHANKAR, S - Institut National De La Recherche Scientifique (INRS); MOSKOVCHENKO, L - Institut National De La Recherche Scientifique (INRS); SALMIERI, S - Institut National De La Recherche Scientifique (INRS); LACROIX, M - Institut National De La Recherche Scientifique (INRS)

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2023
Publication Date: 4/3/2023
Citation: Begum, T., Follett, P.A., Shankar, S., Moskovchenko, L., Salmieri, S., Lacroix, M. 2023. Evaluation of bioactive low-density polyethylene (LDPE) nanocomposite films in combined treatment with irradiation on strawberry shelf-life extension. Journal of Food Science. 88(5):2141-2161. https://doi.org/10.1111/1750-3841.16551.
DOI: https://doi.org/10.1111/1750-3841.16551

Interpretive Summary: In active formulation of silver nanoparticles and cinnamon essential oil was incorporated into low-density polyethylene film to produce a bioactive packaging for preservation of fresh strawberries. Efficacy of the bioactive film with and without irradiation was tested against several pathogenic and spoilage fungi. The film plus irradiation treatment improved food safety and extended shelf life in strawberries.

Technical Abstract: A central composite design (CCD) was performed to develop and optimize active low-density polyethylene (LDPE) based nanocomposite films. The independent variables were cellulose nanocrystals (CNCs) (0 to 0.75 %), active formulation (100 to 300 µL), and glycerol (0.25 to 1 %), while the dependent variable was the inhibitory capacity (IC, %). The active formulation was a mixture of silver nanoparticles (AGPPH) and cinnamon essential oil (EO). Using an agar volatilization assay, the films were tested against two pathogenic bacteria (Escherichia coli O157:H7 and Salmonella Typhimurium) and two spoilage fungi (Aspergillus niger and Penicillium chrysogenum). It has been optimized that the LDPE film containing 300 µL active formulation, 0.375 % CNC, and 0.625 % glycerol showed the highest bactericidal and fungicidal properties (IC =75 %) against all tested bacteria and fungi. The components of the active LDPE nanocomposite film were varied and evaluated for efficacy in fresh strawberries, with or without '-irradiation (500 Gy). The fruits were kept in a polyethylene terephthalate (PET) clamshell box and divided into five groups based on the nanocomposite films added in the PET clamshell and named Group-1 (control) (LDPE/CNC/Glycerol), Group-2 (LDPE/CNC/Glycerol/AGPPH), Group-3 (LDPE/CNC/Glycerol/cinnamon EO), Group-4 (LDPE/CNC/Glycerol/active formulation) and Group-5 (LDPE/CNC/Glycerol/active formulation/500 Gy '-radiation). The Control Group (Group-1) contained the fruits with LDPE nanocomposite films without active agents. The effects of different packaging treatments with or without '-irradiation on the shelf life and quality of fruits during storage at 4°C were evaluated by measuring weight loss (%), decay (%), firmness (N), color (L*, a*, and b*), total phenolic and anthocyanin content. Strawberries kept in clamshell with all active LDPE nanocomposite films exhibited lower weight loss and decay than control samples. The LDPE/CNC/Glycerol/active formulation film and '-irradiation significantly (P = 0.05) reduced the decay and weight loss during storage of strawberries for 12 days than the active film treatment alone. The different packaging treatments did not have any significant effect (P > 0.05) on fruit firmness, but storage time (from 0 to 12 days) did have a significant (P = 0.05) effect. Total phenols and anthocyanin content in strawberries increased with storage time when packed in all active films’ treatments compared to the control (without active film). The nanocomposite films were characterized by mechanical properties (tensile strength-TM, elongation at break-Eb), water vapor permeability (WVP), and surface color properties (L*, a*, b*, 'E). The Eb of active composite films decreased in Group-2, 3, 4, and 5 films compared to the control film (LDPE/CNC/Glycerol). WVP was not influenced by any of the active film components (AGPPH or cinnamon EO or active formulation or '-radiation). The color difference ('E) was significantly affected by AGPPH (Group-2) compared with the control film (LDPE without active formulation). In addition, the combined treatment of active LDPE-nanocomposite films and ' irradiation might be an alternative way to extend the shelf life of storage strawberries as well as maintain the quality of the fruits during storage time.