Industrial Peanut Oil-Cake as a Base Material for the Construction of Nanocapsules Loaded With Oregano Essential Oil...

The objective was to develop and characterize nanocapsules (NPs) employing a peanut oil-cake concentrate (POCC) obtained from the industrial peanut oilcake as wall material incorporated with oregano essential oil (OEO) as core. POCC was employed to fabricate oregano essential oil nanocapsules (OEO-NPs) with different POCC/OEO ratios: control (NPs-0), ratio 1:1 (OEO-NPs-1) and ratio 1:5 (OEO-NPs-5). The average diameter of NPs-0 was 404.00 ± 1.00 nm. The nanoparticle size decreased from 190.63 ± 1.00 nm for OEO-NPs-1 to 164.53 ± 1.00 nm for OEO-NPs-5. The zeta potential found for the different NPs samples highlighted that a long-term stability of the nanoparticles can be expected. The polydispersity index (PDI) value decreased as the amount of OEO added increased. OEO-NPs-5 presented a higher monodispersion in comparison to the other treatments. No porosity or crack zones were detected on the surface of the NPs in the scanning electron microscopy analysis. The encapsulation efficiency (EE) was 91.33%, and 85.15% for OEO-NPs-1 and OEO-NPs-5, respectively. According to the results from the in-vitro OEO release study, the delivery system made by POCC was suitable for controlling the release of OEO. The storage study carried out at 4°C for 90 days showed a decrease in the oxidizing capacity during storage. In general, no significant differences were observed in the volatile compounds profile for OEO-NPs-1 and OEO-NPs-5 during 90 storage days. The POCC demonstrated a good capacity to incorporate OEO with good EE and high release rate control, indicating that NPs made with POCC have potential for food preservation. PRACTICAL APPLICATIONS: Nanocapsules formed from a valueless by-product of the peanut industry and the incorporation of oregano essential oil demonstrated an antioxidant effect, representing an alternative in the food industry for food preservation.