Microcapsule preparation of essential oil of Lippia intergrifolia and its application on peanut seed preservation.

GIRARDI, N.S.; GARCÍA, D.; NESCI, A.; PASSONE, M.A.; ETCHEVERRY, M.

Congreso; BioMicroWorld 2015.VI International Conference on environmental. Industrial and applied Microbiology.; 2015

Microencapsulation technology is one of the most effective methods to date to achieve controlled release of the compounds [1-2]. In this study the use of complex coacervation techniques to microencapsulated essential oil (EO) of Lippia intergrifolia (poleo) and the application of the microcapsules obtained for controlling fungal pathogens of peanut seeds were evaluated. The system of gelatin/gum arabic coacervate was used to produce microcapsules. Reticulation processes were performed with formaldehyde for 10 min and without crosslinking agent. The encapsulation efficiency was determined by using chloroform as agent extraction followed by GC/MS detection. The release of microencapsulated poleo EO was evaluated at different temperatures (4 and 25 °C) of storage and on peanut kernels conditioned at different water activities (0.65, 0.75, 0.85, 0.95 aW). For this, chloroform was used as agent of extraction followed by phenols quantification as estimation of poleo oil residues. To evaluate the effect of microencapsulated poleo EO on peanut mycoflora and germination (PG), a dose of 5000 ppm was applied on shelled and natural peanuts intended for seed purposes (medium and low PG, with and without seed treatment -methyl thiophanate 10% + metalaxyl 1.33% + micronutrients [Co and Mo]-) that were stored for 114 days at room temperature (20-25 °C).Microencapsulation oil process gave efficiency between 99 and 100%. At the end of storage period (78 days), between 3.5 and 63% of poleo EO were released from microcapsules, this action was favoured by the increase of grain aW. The formulation of poleo EO showed a significant antifungal effect on peanut mycoflora, with reductions of about 66%. This inhibition increased when the formulation was applied in combination with the seed treatment (75.6%). However, this formulation caused complete inhibition of peanut seed germination. In conclusion, the gelatin/gum arabic system was effective to encapsulated poleo EO, by allowing controlled release. The microcapsules obtained maintained the antifungal effect of poleo EO, but an adverse effect on peanut seed germination was observed. However, peanut destined to seed is stored unshelled, therefore a change in the implementation methodology could avoid this undesired effect and the application of microencapsulated poleo EO could be considered as a viable strategy for the control of fungal pathogens during the storage of peanut seeds.