| Congresso Brasileiro de Microbiologia 2023 | Resumo: 968-1 | ||||
Resumo:Packages act as barrier technology for preserving food quality, extending shelf life, and reducing losses. Investigations in obtaining active biodegradable coatings have been developed to minimize microbiological contamination and extend postharvest shelf life. Within this context, GRAS products such as oregano (Origanum vulgare) essential oil (OEO) stand out for being a potent antimicrobial agent, however, it presents instability, volatility, and unfavorable effects on sensory properties when applied directly to the food surface. Thus, this work aimed to investigate the development of nanoemulsion of oregano essential oil (NOEO) and its incorporation into the polymeric blend of alginate (ALG) and carboxymethyl cellulose (CMC), for the production of active coatings. The compounds present in OEO were identified by gas chromatography coupled with mass spectrometry. The minimum inhibitory concentration (MIC) was determined by the dilution technique in microplates (96 wells), with an inoculum of Colletotrichum sp. and OEO between 500 and 0.97 µg/mL. The minimum fungicidal concentration (MFC) was made after obtaining the MIC results. Primary emulsion (EOEO) (OEO - 0.25% m/m, Tween 80 - 0.25% m/m, and water) was homogenized in Ultra-Turrax T25, (5 min/ 10,000 rpm). Then submitted to ultrasonic treatment (BS4d34/34mm, 150W/3min), resulting in NOEO. NOEO was added to the polymeric blend of ALG (1% m/m) and CMC (0.5% m/m), crosslinked with calcium chloride(+), (NOEO/ALG(+)/CMC), or without crosslinking(-), (NOEO/ALG(-)/CMC) and homogenized for 5 min. The characterization was done for mean droplet size (nm), polydispersity index (PDI), and ζ-potential, measured by dynamic light scattering (DLS) (Zetasizer Nano Series). Stability was observed visually during 30 days. The in vitro antifungal activity of the nanoemulsions was evaluated by microplate dilution technique (96 wells). Of the 16 compounds found, Carvacrol = p-Cimen-2-ol = Isothymol was the main compound identified (60.75%). The MIC was 62.50 µg/mL. At concentrations of 500 and 250 µg/mL, the OEO exerts fungicidal action, inhibiting 100% of mycelial growth. The mean droplet size of NOEO was 132.93 nm. NOEO/ALG(+)/CMC showed smaller droplet sizes (p ≤ 0.05) when compared to NOEO/ALG(-)/CMC, 531.20 and 717.98 nm, respectively. NOEO showed a lower polydispersity index. There was no difference (p > 0.05) between NOEO/ALG(+)/CMC and NOEO/ALG(-)/CMC samples, despite the low polydispersity index in the nanoemulsions, crosslinking did not influence the droplet size homogeneity and stability. NOEO had a negative ζ-potential value (-16.85), however, NOEO/ALG(-)/CMC presented a lower ζ-potential (-25.95 mV), remaining stable, as observed in the visual analysis. The addition of the nanoemulsion to the polymeric blend (NOEO/ALG(+)/CMC and NOEO/ALG(-)/CMC) changed the appearance of the solution to milky white, however, after 30 days these samples were still homogeneous, with a yellowish hue. The in vitro analysis showed that there was no growth in the wells inoculated with NOEO, NOEO/ALG(+)/CMC, and NOEO/ALG(-)/CMC solutions, confirming the antimicrobial activity of the nanoemulsions. It can be concluded that the nanoemulsions were stable and evidenced the efficiency of the polymeric blend developed for this work and its use can be an effective alternative in the development of active coatings for use in post-harvest. Palavras-chave: biopolymer, fruits and vegetables, essential oil, antifungal activity, edible coating Agência de fomento:Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro [E- 26/202.186/2020; E- 26/204.328/2021]. | |||||