Effect of ginger essential oil on citrus fruit decay when applied in a nano-emulsion coating

Authors: MIRANDA, MARSELA - Sao Paulo State University (UNESP); MARCOS, DAVID - Embprapa; GARRIDO ASSIS, ODILIO BENEDITO - Sao Paulo State University (UNESP); Sun, Xiuxiu; Ference, Christopher; Plotto, Anne; Bai, Jinhe; Baldwin, Elizabeth - Liz

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/16/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Fruits and vegetables losses from harvest to consumption are estimated to be around 40 and 50% of the total production. Tangerine is a non-climateric fruit, very perishable and highly susceptible to post-harvest pathogens. Edible coatings are considered an attractive alternative for fruit preservation, as they can provide an efficient gas barrier, reduce moisture loss, and in some cases, act as an antimicrobial agent. Carnauba wax nanoemulsioncoatings were more compatible to the incorporation of essential oil due to smaller sized lipid micelles in the coating structure. The combination of lipids and anti-microbial ginger extracts into carnauba wax nanoemulsion, have the potential to reduce produce decay. Therefore, the main aim of this study was to evaluate ginger extracts and essential oil antifungal in vitro activity and antimicrobial nanoemulsion edible coatings effects to preserve fruit quality and decrease decay. First, the antimicrobial activity of ginger oil and extracts was evaluated using the follow analyses: Poisoned Food Technique (PFT), Inverted Petri-dishes Test (IPD) and Penicillium digitatum spore germination percentage rate. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were carried out for P. digitatium and Colletotrichum gloeosporioides. Second, "Nova' mandarin fruits were coated with commercial carnauba and shellac microemulsions and experimental carnauba nanoemulsion. All treatments were compared to uncoated fruit, used as control. Fruit quality evaluation included weight loss, gloss, soluble solids (SS), titratable acidity (TA), pH, SS/TA ratio, internal carbon dioxide (CO2) and oxygen (O2), ethanol, and a sensory shine rank test after storage at 20°C for 7 days. After, the effect of 0.8% Ginger Essential Oil (GEO) added in a nanoemulsion coating was tested on "Unique" tangerines stored for 14 days in cold temperature (10 °C) followed by a simulated marketing period. Fruit quality and effect of this antimicrobial-coating on disease development were performed for natural decay and for P. digitatum-inoculated fruit.The results showed that conventional and nanoemulsion carnauba wax resulted in the least weight loss compared to control and shellac. There were no differences for gloss measurements, but fruit gloss decreased with time and shellac-coated fruit ranked highest for shine in sensory tests. There were no practical differences for SS, TA, pH and ratio among treatments. CO2 and ethanol generally increased and O2 decreased during storage, while the highest levels of CO2 and ethanol were found for the shellac treatment along with the lowest O2, indicating fermentation, with no differences among the other treatments. GEO generally exhibited higher antimicrobial activity than the other ginger extracts. The combination of nanoemulsion and GEO into a coating was more effective in vitro experiment than in vivo. Higher concentrations of GEO in nanoemulsion coatings will be tested in future experiments, as GEO showed promising antimicrobial ability for application in edible coatings for fruits.