Encapsulation of thyme essential oil using electrospun zein fiber for strawberry preservation

BACKGROUND: Strawberry is a nutrient-rich and important small fruit because of its high content of beneficial phytochemicals and several vitamins like vitamin C, vitamin E and vitamin B6. However, strawberry is highly perishable due to its susceptibility to mechanical damage, microbiological decay, and softening in texture. Recently, there has been an increasing interest in using various essential oils as natural food preservatives. Although, they have limited stability to exposure to high temperatures, light and oxygen, which could eventually affect sensory quality attributes. The electrospinning method is a simple and well-organized process that has been used to encapsulate essential oils. In this study, the effect of thyme essential oil (TEO) encapsulated into zein electrospun fiber film was assessed on extending the shelf life and preserving the quality of strawberry fruit during storage. FINDINGS: Results indicated that TEO presented potent antibacterial activity against Bacillus cereus, Escherichia coli and Aspergillus fumigatus. The scanning electron microscopy images of zein fiber had a linear shape, absence of beads, and smooth surface. The encapsulation efficiency (EE) of TEO in the zein fiber was about 75.23%. Encapsulated TEO released at a slower rate than free TEO. The zein/TEO fibers (zein fiber film loaded with TEO) significantly (p ˂ 0.05) decreased weight loss and maintained the anthocyanin content, firmness and color of the strawberries during storage. After 15 days of storage, weight loss reduced about 15% and firmness was higher about 20% in packed fruit with zein/TEO fibers compared to control. CONCLUSIONS: Interestingly, after 15 days of cold storage, the strawberries firmness, appearance, and sensory evaluation, which are important quality factors from both postharvest and consumers’ viewpoint, in zein/TEO fiber treatment were acceptable and had higher scores compared to the control. In conclusion, the present study demonstrated the benefits of incorporating TEO into zein films, which could play a significant role in the active packaging and preservation of strawberry fruits.