Antifungal and functional properties of starch-gellan films containing thyme (Thymus zygis) essential oil

The Efficiency of Deoxynivalenol Degradation by Essential Oils under In Vitro Conditions

Essential oils (EOs) are complex natural products of plant origin and exhibit different desirable, e.g., antimicrobial properties. Their growth inhibition effect on the pathogenic fungi of the genus, Fusarium, which forms deoxynivalenol (DON), has been documented. DON is the most common contaminant of grains and their products, causing strong emetic effects after their consumption. The aim of the study was to investigate the ability of selected EOs to degrade DON under in vitro conditions, using various incubation terms. The impact of a different temperature, pH, incubation time, mycotoxin, and essential oil concentration was tested. The results indicate that the kind of EO influences the effectiveness of mycotoxin level reduction, and the most effective EOs were palmarosa and lemon oils. A higher reduction of DON content by EOs was achieved after 24 h of the experiment (up to 72%), at a pH range between 3 and 6 and a temperature of 20 °C. Moreover, the effect of various doses of white and pink grapefruit and palmarosa EOs (100 and 200 μL/mL) on toxin level reduction was observed. The experiment confirmed that the selected EOs may be effective in DON reduction, as previously documented in experiments with zearalenone.

Alginate Films Encapsulating Lemongrass Essential Oil as Affected by Spray Calcium Application

The necessity of producing innovative packaging systems has directed the attention of food industries towards the use of biodegradable polymers for developing new films able to protect foods and to extend their shelf-life, with lower environmental impact. In particular, edible films combining hydrophilic and hydrophobic ingredients could retard moisture loss, gas migration and ensure food integrity, reducing the necessity of using synthetic plastics. Alginate-based films obtained from emulsions of lemongrass essential oil (at 0.1% and 0.5%) in aqueous alginate solutions (1%), with Tween 80 as surfactant (0.3%), were obtained by casting and characterized as to microstructure and thermal behavior, as well as tensile, barrier and optical properties. Films were also crosslinked through spraying calcium chloride onto the film surface and the influence of oil emulsification and the crosslinking effect on the final film properties were evaluated. The film microstructure, analyzed through Field Emission Scanning Electron Microscopy (FESEM) revealed discontinuities in films containing essential oil associated with droplet flocculation and coalescence during drying, while calcium diffusion into the matrix was enhanced. The presence of essential oil reduced the film stiffness whereas calcium addition lowered the film’s water solubility, increasing tensile strength and reducing the extensibility coherent with its crosslinking effect.

Characterization and application of the microencapsulated carvacrol/sodium alginate films as food packaging materials

The carvacrol (CAR) was microencapsulated by β-cyclodextrin (βCD). To extend the shelf-life of white mushrooms against Trichoderma sp., the microencapsulated CAR (βCD-CARM)/sodium alginate (SA) films were prepared and characterized. The antifungal, physical, and mechanical properties of the films were investigated in this study. The results showed that the βCD-CARM with a core-to-wall ratio of 1:10 had better encapsulation efficiency and antifungal activity against Trichoderma sp., which was isolated from postharvest white mushrooms stored at 4 °C. The optimum concentration of βCD-CARM against Trichoderma sp. in vitro was 15 g/L. The water resistance, mechanical properties, light barrier property and heat aging of the film were enhanced after adding βCD-CARM. The films with 30 g/L βCD-CARM could efficiently against Trichoderma sp. The performance of βCD-CARM/SA films was confirmed to control the release of CAR for enhanced antifungal activity. Besides, the βCD-CARM/SA films increased the activities of active free-radical scavenging enzymes to alleviate oxidative damage and delay senescence of the postharvest white mushrooms.

Antibacterial activity, optical, mechanical, and barrier properties of corn starch films containing orange essential oil

The incorporation of antimicrobial compounds into natural polymers can promote increased shelf life and ensure food safety. The aim of this study was to evaluate the antibacterial activity, morphological, optical, mechanical, and barrier properties of corn starch films containing orange (Citrus sinensis var. Valencia) essential oil (OEO). The corn starch films were prepared using the casting method. OEO and the corn starch films incorporated with OEO showed higher antibacterial activity against Staphylococcus aureus and Listeria monocytogenes. The addition of OEO to the films increased the morphological heterogeneity and contributed to the reduction of the tensile strength and elongation of the films, and it increased the moisture content, water solubility, and water vapor permeability. The water vapor permeability and partial or total solubility of a film in water prior to consumption of a product are of interest when the film is used as food coating or for encapsulation of specific molecules.

Antifungal Starch–Gellan Edible Coatings with Thyme Essential Oil for the Postharvest Preservation of Apple and Persimmon

Starch–gellan (80:20) coating formulations were applied to apples and persimmons to analyse their effectiveness controlling the weight loss, respiration rate, fruit firmness, and fungal decay during postharvest. Thyme essential oil (EO) was incorporated (0.25 and 0.5 g per g of polymer) directly or encapsulated in lecithin to enhance antifungal action. Coatings did not reduce weight loss or firmness changes in apples, but they prevented water loss in persimmons. In contrast, no significant effect of the coatings was observed on the respiration rates and the respiration quotient of persimmons, whereas the respiration rates and quotient was increased in apples. On the other hand, the coatings without lecithin reduced the incidence and severity of black spot caused by Alternaria alternata in persimmons, regardless of the content of essential oil. Likewise, these reduced the severity of gray mold caused by Botrytis cinerea in apples. No positive effect of lecithin in coatings was observed on the postharvest quality and decay in either apples or persimmons, nor did EO exert antifungal action despite its proven effectiveness in in vitro tests.