| Congresso Brasileiro de Microbiologia 2023 | Resumo: 968-2 | ||||
Resumo:During the production chain, fruits face problems due to their susceptibility to postharvest rot, preferably by fungi, reducing their shelf life. Active biodegradable coatings with essential oil have been developed in order to minimize microbiological contamination and extend postharvest shelf life. Oregano (Origanum vulgare) essential oil (OEO) is a product considered GRAS and stands out as an antimicrobial agent. The aim of this work was to investigate the development of different OEO nanoemulsions, evaluate their antifungal potential against Colletotrichum sp. and the application of active coatings in papaya post-harvest. Primary emulsion (EOEO) (water, OEO (0.25% m/m) and Tween 80 (0.25% m/m)) was prepared by homogenization in Ultra-Turrax T25 (5 min/10,000 rpm). Then submitted to ultrasonic treatment (150W for 3 min), resulting in the sample called OEO Nanoemulsion (NOEO). NOEO was added to the polymeric mixture of Alginate (ALG) and carboxymethyl cellulose (CMC) (1% m/m and 0.5% m/m, respectively), crosslinked with calcium chloride(+), (NOEO/ALG(+)/CMC), or without crosslinking(-), (NOEO/ALG(-)/CMC) and homogenized for 5 min. The characterization of the nanoemulsions was done in terms of mean droplet size (nm), polydispersity index (PDI) and potential ζ, measured by dynamic light scattering (DLS) (Zetasizer Nano Series). To evaluate the effect of nanoemulsions on mycelial growth of Colletotrichum sp. isolate, Petri dishes containing BDA were added with 100 µL of filmogenic solution. Mycelial agar discs (8 mm) were transferred to the center of the plate and incubated in BOD at 25 ± 0.5 °C for 15 days and the orthogonal diameters of the colonies were measured. The antifungal activity of the nanoemulsions were evaluated in vivo. Peels (epidermis) of papaya were cut into uniform slices (3 cm), coated with 200µL of the solutions, followed by artificial inoculation (10 µL of Colletotrichum sp. spore suspension, (3.6 x 106)) and evaluated after 72h. The average droplet size of the nanomulsion in water (NOEO) was 131.80 nm. Among the formulations, the cross-linked nanoemulsions (NOEO/ALG(+)/CMC) showed the smallest droplet sizes when compared to the non-cross-linked nanoemulsions (NOEO/ALG(-)/CMC), of 542.70 and 679.30 nm, respectively. NOEO presented lower polydispersity index. Crosslinking did not influence the droplet size homogeneity and stability. All the nanoemulsions presented ζ-potential below - 30 mV, being stable. However, the polymeric nanoemulsion without crosslinking (NOEO/ALG(-)/CMC) presented the highest negative ζ-potential (- 23.72 mV). NOEO caused inhibition of mycelial growth for the Colletotrichum sp. isolate until the 5th day of evaluation. Colletotrichum sp. when in contact with NOEO/ALG+/CMC and NOEO/ALG-/CMC solutions showed lower growth velocity, when compared to solutions without OEO. Polymeric nanoemulsions (NOEO/ALG+/CMC and NOEO/ALG-/CMC) acted as a potent antimicrobial agent, considering only 22% of contaminated papaya peels after 72h. While peels coated only with ALG/CMC showed 100% contamination. Thus, it was observed that the nanoemulsions were stable and evidenced the efficiency of the developed polymer mixture. The addition of the nanoemulsion to the polymeric mixture (NOEO/ALG(+)/CMC and NOEO/ALG(-)/CMC) confirms the antimicrobial activity of the nanoemulsions and its use can be an effective alternative in the development of active coatings with antimicrobial activity for use in papaya post-harvest. Palavras-chave: post-harvest, papaya, essential oil, antifungal, 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]. | |||||