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

GIRARDI, NATALIA S.; GARCIA, DAIANA; NESCI, ANDREA; PASSONE, MARÍA A.; ETCHEVERRY, MIRIAM

Barcelona

Congreso; VI International Conference of Environmental, Industrial and Applied Microbiology ? BioMicro World 2015; 2015

Microencapsulation technology is one of the most effective methods to dateto achieve controlled release of the compounds [1-2]. In this study the use ofcomplex coacervation techniques to microencapsulated essential oil (EO) of Lippia intergrifolia (poleo) and theapplication of the microcapsules obtained for controlling fungal pathogens ofpeanut seeds were evaluated. The systemof gelatin/gum arabic coacervate was used to produce microcapsules.Reticulation processes were performed with formaldehyde for 10 min and withoutcrosslinking agent. The encapsulation efficiency was determined by usingchloroform as agent extraction followed by GC/MS detection. The release ofmicroencapsulated 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 extractionfollowed by phenols quantification as estimation of poleo oil residues. Toevaluate the effect of microencapsulated poleo EO on peanut mycoflora andgermination (PG), a dose of 5000 ppm was applied on shelled and natural peanutsintended for seed purposes (medium and low PG, with and without seed treatment -methylthiophanate 10% + metalaxyl 1.33%  + micronutrients[Co and Mo]-) that were stored for 114 days at room temperature (20-25 °C).Microencapsulationoil 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, thisaction was favoured by the increase of grain aW. The formulation ofpoleo EO showed a significant antifungal effect on peanut mycoflora, withreductions of about 66%. This inhibition increased when the formulation wasapplied in combination with the seed treatment (75.6%). However, thisformulation caused complete inhibition of peanut seed germination. In conclusion, the gelatin/gum arabic system waseffective to encapsulated poleo EO, by allowing controlled release. Themicrocapsules obtained maintained the antifungal effect of poleo EO, but anadverse effect on peanut seed germination was observed. However, peanutdestined to seed is stored unshelled, therefore a change in the implementationmethodology could avoid this undesired effect and the application ofmicroencapsulated poleo EO could be considered as a viable strategy for thecontrol of fungal pathogens during the storage of peanut seeds.