Preservation of strawberry fruit quality via the use of active packaging with encapsulated thyme essential oil in zein nanofiber film

Strawberry is highly perishable with a short shelf life mainly due to physiological deterioration and microbiological decay. Thyme essential oil (TEO), which is a natural antimicrobial and antioxidant agent, encapsulated in zein (Z) nanofiber could be used by electrospinning to examine the ability of the nanofiber for strawberry quality preservation. Test groups were designated as zein nanofiber film, and zein loaded with TEO nanofiber film (Z/TEO). The fruit packed in PET container without film on its lid was used as the control group. Packages of fruits were then stored in a cool room at 4 ± 0.5 °C and 85 ± 5% RH for 15 days. Results indicated that the scanning electron microscopy images of nanofibers had a linear morphology, smooth surface and bead-free structure. Fourier transform infrared also showed that the encapsulation of TEO in the zein was a physical process and no chemical interactions occurred between ingredients during electrospinning. Moreover, differential scanning calorimetry data confirmed the thermal stability of TEO encapsulated in zein nanofibers. Active packaging including nanofiber films significantly preserved the biochemical and microbial properties of fruit. Indeed, stored fruit in packages containing nanofiber Z/TEO (Zein loaded with TEO nanofiber film) significantly (p˂0.05) lowered total bacterial counts, fungi and yeast, and maintained the total phenols content, antioxidant activity and titratable acidity of the strawberries during 15 days of storage at 4 °C. In conclusion, this study revealed the benefits of incorporating TEO into zein films, which may have a great potential in active packaging and preservation of strawberry fruits.