Introduction: Postharvest losses can occur anywhere from harvesting to handling and shipping. In 2014, approximately $30 billion of fresh produce were lost in the United States food supply chain. In particular, small fruits shelf-life can be reduced by weight loss, stem scar injury, gray mold and ripe rot. It is important therefore find sustainable packing alternative to protect produce, increase shelf-life, minimize waste and preserve resources.
Purpose: The objective of this study was to evaluate the mechanical, physical and anti-fungal properties of packaging films loaded with essential oil (EO) nanoemulsions.
Methods: Food-grade emulsions with sub-micron droplets were used to encapsulate cinnamaldehyde (CY), eugenol (E) and thymol (T) within a refined coconut oil (carrier) in pullulan packaging systems (formulated in a previous work). Different film combinations (5 - 10% Pullulan, 1 - 2 % EO, 0 – 50 % water, 0.5 – 1 % gum concentrations) loaded with EO nanoemulsions were investigated. Tensile strength, moisture content and antifungal activity against Rhizopus stolonifer, Alternaria spp. and Aspergillus niger were measured and compared to control pullulan systems.
Results: A lower tensile strength (P > 0.05) was measured for combinations loaded with EO nanoemulsions as compared to films without active lipid solutions: 5.7, 7.9, 6.8 and 17.1 MPa for CY, E, T and control system, respectively. Nevertheless, the active combinations presented good elasticity and ductility. Active films moisture contents were lower as compared to film without EO (P < 0.05). The control formulations showed no antifungal activity. Conversely, active combinations exhibited significant inhibition zones (P < 0.05). Film containing CY had the biggest inhibition halos: 13.7, 15.7 and 14.5 mm were measured against R. stolonifer, Alternaria and A. niger, respectively.
Significance: This study demonstrates the potential application of pullulan packaging films loaded with EO nanoemulsions as a mean of controlling and reducing postharvest disease in small fruits during shipping and storage.

Valentina Trinetta

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