Preparation and Application of LDPE/ZnO Nanocomposites for Extending Shelf Life of Fresh Strawberries
Aryou Emamifar1* and Mehri Mohammadizadeh2
1Department of Food Science and Technology, University of Kurdistan, 66177-15177 Pasdaran Street,
Sanandaj, Kurdistan, Iran
2Department of Food Science and Technology, Science and Research Branch, Islamic Azad University of
Kurdistan, 6616935391, Feiz Abad, Sanandaj, Kurdistan, Iran
Article history:
Received July 15, 2014
Accepted May 22, 2015
Key words:
strawberry, ZnO nanoparticles, nanocomposite, antimicrobial packaging
Summary:
Strawberries have a very short post-harvest life mostly due to their relatively high water content, intense metabolic activity and susceptibility to microbial rot. Antimicrobial low-density polyethylene nanocomposite films containing ZnO nanoparticles at different mass fractions were prepared by melt mixing and followed by compression moulding using a hot press machine. Fresh strawberries were packed in nanocomposite films and stored at 4 °C. Their microbial stability, ascorbic acid content and titratable acidity were evaluated aft er 0, 4, 8, 12 and 16 days of storage. Microbial growth rate was significantly reduced up to 16 days as a result of the use of nanocomposite packaging material containing ZnO nanoparticles. By increasing the ZnO nanoparticle mass fraction to 5 %, the antimicrobial activity of the film increased. All packages containing the ZnO nanoparticles kept the microbial load of fresh strawberries below the level that affects shelf life (5 log CFU/g) up to 16 days. The lowest degradation of ascorbic acid content (6.55 mg per 100 g), and loss of acidity (0.68 %) were observed in packages containing 3 % of ZnO nanoparticles with 10 % polyethylene-grafted maleic anhydride.
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