Microencapsulation of Peumus boldus oil by complex coacervation to provide peanut seeds protection against fungal pathogens

• Optimal encapsulation conditions were formaldehyde; 10 min; 240 gelatin bloom.
• Gelatin-gum arabic system allowed boldo oil microencapsulation with high efficiency.
• Low levels of boldo oil were released from microcapsules after 12 days of storage.
• The boldo formulation reduced significantly the fungal development on peanut seeds.
• An adverse effect on seed germination was produce by the formulation.

In this study, Peumus boldus Mol. (boldo) essential oil (EO) microcapsules were prepared using the complex coacervation technique with gelatin/gum arabic, in order to enhance the dwell period of this preservative in the storage system. Bloom gelatin 240 − formaldehyde 10 min were the optimal encapsulation conditions (94.38%). The microcapsules prepared under optimal conditions had an average diameter of 5.67 μm. Boldo EO release was very low at 12 days of incubation (1 × 10−4%) and was not affected by temperature. In grains, 99.9% of EO remained encapsulated at the end of the incubation period (10 days), including at the highest aW tested (0.95). Boldo EO formulation reduced between 31.5 and 42.5% the peanut mycoflora being Penicillium and Aspergillus the main species isolated from control and treated seeds. However, volatile compounds released by the formulation decreased the germination capacity of peanut seeds. To avoid this effect, the implementation of boldo EO formulation on stored shell peanut will be evaluated in future studies.In conclusion, boldo EO was encapsulated with high percentages of efficiency by complex coacervation keeping the antifungal ability. The application of boldo EO formulation could increase seed protection against fungal pathogens during a storage period of 114 days, if it possible to reduce the allelophatic effect.

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