Atividade Antifúngica de Extratos e Óleo Essencial de Gengibre em Revestimentos Nanoestruturados de Cera de Carnaúba na Conservação Pós-colheita de Tangerina e Mamão
Carregando...
Data
2020-07-31
Autores
Miranda, Marcela
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Objetivo: O objetivo deste estudo foi avaliar a atividade antifúngica de extratos alcoólicos de gengibre e de óleos essenciais, contra fitopatógenos pós-colheita, de forma isolada ou associada à nanoemulsão de cera de carnaúba na conservação da qualidade e redução da deterioração natural ou induzida em tangerinas e mamões. Formulações com nanoemulsão de cera de carnaúba e suas associações com hidroxipropil metilcelulose (HPMC), como agente adjuvante na formação de filme, e com a incorporação de óleo essencial de gengibre (GEO), foram aplicadas como revestimento protetor e avaliadas sob diversas condições de armazenamento. Metodologia: Extratos alcoólicos (GEs) e óleos essenciais (GEOs) foram extraídos de rizomas de gengibre. A atividade antifúngica desses compostos foi avaliada contra P. digitatum, P. expansum, F. solani e A. alternata in condições in vitro. Dois experimentos foram realizados com tangerinas (‘Nova’ mandarins). Estas frutas foram revestidas com microemulsões de goma laca (shellac) e cera carnaúba, e também com formulações nanoparticuladas (nanoemulsões) e comparadas com frutos não revestidos após 7 dias de armazenamento a 20 °C. Os revestimentos também foram testados em tangerinas 'Unique' armazenadas por 14 dias a 10 °C, seguido por um período de simulação de comercialização (7 dias a 20 ºC). A avaliação da qualidade dos frutos incluiu perda de peso, brilho, sólidos solúveis, acidez titulável, pH, ratio, CO2 e O2 interno, etanol, teste sensorial e de brilho após 7 dias a 20 °C. Para ensaios pós-colheita com mamões, as formulações filmogênicas foram preparadas nas concentrações de 9% e 18% de nanoemulsão de cera de carnaúba. HPMC foi usado como revestimento controle inerte, a GEO (a 3% v/v), testado como composto ativo contra infestações por fungos. Os frutos foram armazenados e avaliados em dois experimentos separados. O primeiro, realizado após 6 dias a 22 °C e 9 dias a 13 °C, seguidos por 5 dias à temperatura ambiente para simular as condições de comercialização. No segundo ensaio, mamões foram armazenados por 5 dias a 22 °C e 10 dias a 16 °C antes da condição de comercialização simulada, que foi de 3 dias a 22 °C. Análises pós-colheita e ação protetora na redução da severidade de doenças naturais e disseminação de fungos em amostras inoculadas com C. gloeosporioides e análise sensorial foram conduzidas. Resultados: Os GEOs apresentaram uma maior efetividade que os GEs e em concentrações inibitórias mínimas (MIC), menores para os óleos que as medidas para os extratos alcoólicos. Os GEs não apresentaram ação fungicida contra os fungos avaliados (MCF) na maior concentração testada (6%) em meio líquido. Na condição in vitro, os GEOs apresentaram uma melhor atividade antifúngica que os GEs, sendo mais apropriado para incorporação em revestimentos no controle de doenças pós-colheita. GEOs nos ensaios em in vitro apresentaram uma melhor atividade que os testes conduzidos em in vivo. O fungo P. digitatum apresentou maior sensibilidade aos compostos de gengibre (com menor concentração inibitória mínima), seguido por A. alternata, F. solani e P. expansum (para os quais foram necessários maiores concentração das amostras para que ocorra a inibição do crescimento micelial). Para tangerinas, revestimentos com microemulsão e nanoemulsão de cera de carnaúba resultaram na menor perda de peso em comparação ao controle e shellac. Não houve diferenças nas medidas de brilho para a 'Nova', no entanto, os frutos revestidos com shellac tiveram a maior classificação de brilho no teste visual. Todavia, para ‘Unique’, inicialmente, a cobertura de shellac resultou no maior brilho, entretanto no final do armazenamento, a nanoemulsão reteve o maior brilho comparativamente, embora não diferente da microemulsão. Os teores de CO2 e etanol aumentaram e de O2 diminuiu internamente durante o armazenamento para todos os tratamentos. Os maiores níveis de CO2 e etanol foram verificados para shellac juntamente com menor O2, indicando fermentação, sem diferenças entre os demais tratamentos. Shellac e a microemulsão também alteraram o perfil dos compostos voláteis, porém mais que os frutos do controle ou a nanoemulsão, especialmente para ‘Unique’. Em relação aos ensaios com mamões, todos os revestimentos forneceram alguma proteção, com variações nos efeitos decorrentes das condições de armazenamento e das composições das formulações. Sob armazenamento refrigerado, a maioria das análises não resultou em diferenças significativas entre as amostras. Sob temperatura ambiente e após condições simuladas de mercado, as diferenças tornam-se mais evidentes. As coberturas com nanoemulsão foram capazes de manter melhor a qualidade do mamão sobre as condições de armazenamento e mercado. Foram registradas maiores reduções na perda de firmeza, alterações de cor e taxa de respiração, atuando positivamente no atraso da maturação. Não foram relatadas alterações nos atributos como doçura, acidez, papaya flavour ou presença de sabores estranhos relacionados à fermentação interna, devido à cobertura, nos testes sensoriais. O GEO apresentou efeito na redução de doenças na superfície do mamão, principalmente quando associado à carnaúba, embora nenhuma ação tenha sido observada na inibição do crescimento de C. gloeosporioides após a inoculação. Conclusão: Os GEOs mostraram ser os agentes mais indicados para serem empregados no controle pós-colheita de fungos, por exibirem uma maior atividade antifúngica que as encontradas nos extratos alcoólicos. A combinação de nanoemulsão e GEO em revestimentos foram mais eficazes nos experimentos in vitro do que in vivo. Para os ensaios de tangerinas, as emulsões de carnaúba resultaram em uma menor perda de água, conferiram brilho e causaram menor produção de etanol do que o shellac com a nanoemulsão exibindo maior brilho após refrigeração. Menores também foram as modificações da atmosfera interna e do perfil de voláteis e, consequentemente, preservou o sabor comparado a microemulsão. As coberturas com nanoemulsões de cera de carnaúba foram mais adequadas na proteção e na manutenção da qualidade dos mamões em condições de armazenamento e de mercado. A incorporação de GEO nos revestimentos promoveu a redução de doenças nos mamões, principalmente quando combinado com a nanoemulsão de cera de carnaúba.
Objective: The aim of the present study was the evaluation of the antifungal activity of ginger alcoholic extracts and essential oils against common post-harvest phytopathogens, as isolated compounds or in association to carnauba wax nanoemulsion. In coating format these composites are able to preserve quality and slow down natural or induced decay on tangerines and papayas. Formulation based in carnauba wax nanoemulsions and their association with hydroxypropyl methylcellulose (HPMC), as a neutral film forming adjuvant, and ginger essential oil (GEO) incorporation, were applied as protective coatings and evaluated under several conditions of storage. Methodology: Alcoholic extracts (GEs) and essential oils (GEOs) were extracted from ginger rhizomes. Antifungal activities of GEs and GEOs were evaluated in vitro against P. digitatum, P. expansum, F. solani and A. alternata. Two experiments were performed with citrus (Nova’ mandarins). These fruits were coated with shellac and carnauba microemulsions, as well as nanoparticulated carnauba (nanoemulsions) and compared with uncoated control fruits after 7 days storage at 20 °C. Coatings were also tested on ‘Unique’ tangors stored for 14 days at 10 °C followed by a simulated marketing period of 7 days at 20 ºC. Fruit quality evaluation included weight loss, gloss, soluble solids (SS), titratable acidity (TA), pH, SS/TA ratio, internal CO2 and O2, ethanol, and a sensory shine rank test after storage at 20°C for 7 days. For papaya postharvest assays, the formulation was prepared in a concentration of 9% and 18% (w/v) carnauba wax nanoemulsion. HPMC was used as inert coating control and GEO (at 3% v/v) tested as active compounds against fungal infestation. The fruits were stored and evaluated in two separate experiments. The first conducted after 6 days at 22 °C and 9 days at 13 °C followed by 5 days at room temperature to simulate marketing conditions. In the second assay papayas were stored for 5 days at 22 °C, and 10 days at 16 °C before simulated marketing condition of 3 days at 22 °C. Post-harvest analyzes and protective action towards reducing natural diseases severity and inhibit of fungal spread on samples inoculated with C. gloeosporioides, were performed along with sensory evaluations. Results: GEOs showed a more effectiveness than GEs and at minimum inhibitory concentration (MIC) lower for oils than those measured to alcoholic extracts. The GEs did not show minimum fungicidal concentration (MCF) against the tested fungi even at the highest concentration tested (6%) in broth medium. GEOs on in vitro conditions showed a better antifungal activity than GEs, indicating that they are more appropriate for incorporation into edible coatings, aiming phytopathogenic postharvest microorganism’s control. When in vitro assessment, the GEO showed a better antifungal activity than the in vivo conducted tests. The P. digitatum fungus was the most sensible to ginger compounds (with lower MIC), followed by A. alternata, F. solani and P. expansum, in this order. These required higher concentrations to attain mycelial inhibition. For tangerines, conventional and nanoemulsion carnauba wax resulted in inferior weight loss compared to control and shellac. There were no differences for gloss measurements for ‘Nova’ mandarins, however, shellac-coated fruit ranked highest for shine in visual sensory assessment. For ‘Unique’ tangors, initially, the shellac coating promoted the highest gloss (shine), but at the end of storage, the nanoemulsion exhibited the highest gloss measurement, although not different from the microemulsion. CO2 and ethanol generally increased and O2 decreased internally during storage for all treatments. The highest levels of CO2 and ethanol were measured in shellac treated samples along with the lowest O2, indicating internal fermentation, with no differences among the other treatments. Shellac and the carnauba microemulsion also altered the volatile profile more intensely than control or nanoemulsion coating, especially for ‘Unique’ tangors. For papaya, all coatings provided some protection, with variations on the effects due to storage conditions and between formulations compositions. Under cold storage, most of analyzes did not resulted in any statistically significant differences among samples. At room temperature and after simulated market conditions the differences become more evident. The nanoemulsions were able to a better maintaining of papaya quality over storage and market conditions. Higher reductions on loss of firmness, color alterations and respiration rate were recorded, with positive action in delaying maturity. No changes in attributes as sweetness, sourness, papaya flavor or the presence of off-flavors related to internal fermentation were reported in the sensory test. The GEO presented some effect in reducing natural diseases on papaya skin, particularly when associated with carnauba, although no action was observed in inhibiting C. gloeosporioides fungal growth after inoculation. Conclusion: GEOs proved to be the most indicated for use as active agents for application in post-harvest fungal control since, in general, they exhibited higher antifungal activity than the alcoholic extracts. The combination of nanoemulsion and GEO into a coating was more effective in vitro experiment than in vivo. For tangerine assays among the coatings tested, the carnauba emulsions resulted in lesser water loss, imparted more sustainable shine, and caused less ethanol production than did shellac. The carnauba nanoemulsion coatings also exhibited higher shine and fewer modifications of the atmosphere and volatiles profile, and consequently assuring a better flavor compared to the microemulsion. Papayas coated with carnauba wax nanoemulsions had the quality preserved over storage and market conditions. The incorporations of GEO into coatings, promoted a reduction of natural diseases on papaya skin, mainly when combined with carnauba.
Objective: The aim of the present study was the evaluation of the antifungal activity of ginger alcoholic extracts and essential oils against common post-harvest phytopathogens, as isolated compounds or in association to carnauba wax nanoemulsion. In coating format these composites are able to preserve quality and slow down natural or induced decay on tangerines and papayas. Formulation based in carnauba wax nanoemulsions and their association with hydroxypropyl methylcellulose (HPMC), as a neutral film forming adjuvant, and ginger essential oil (GEO) incorporation, were applied as protective coatings and evaluated under several conditions of storage. Methodology: Alcoholic extracts (GEs) and essential oils (GEOs) were extracted from ginger rhizomes. Antifungal activities of GEs and GEOs were evaluated in vitro against P. digitatum, P. expansum, F. solani and A. alternata. Two experiments were performed with citrus (Nova’ mandarins). These fruits were coated with shellac and carnauba microemulsions, as well as nanoparticulated carnauba (nanoemulsions) and compared with uncoated control fruits after 7 days storage at 20 °C. Coatings were also tested on ‘Unique’ tangors stored for 14 days at 10 °C followed by a simulated marketing period of 7 days at 20 ºC. Fruit quality evaluation included weight loss, gloss, soluble solids (SS), titratable acidity (TA), pH, SS/TA ratio, internal CO2 and O2, ethanol, and a sensory shine rank test after storage at 20°C for 7 days. For papaya postharvest assays, the formulation was prepared in a concentration of 9% and 18% (w/v) carnauba wax nanoemulsion. HPMC was used as inert coating control and GEO (at 3% v/v) tested as active compounds against fungal infestation. The fruits were stored and evaluated in two separate experiments. The first conducted after 6 days at 22 °C and 9 days at 13 °C followed by 5 days at room temperature to simulate marketing conditions. In the second assay papayas were stored for 5 days at 22 °C, and 10 days at 16 °C before simulated marketing condition of 3 days at 22 °C. Post-harvest analyzes and protective action towards reducing natural diseases severity and inhibit of fungal spread on samples inoculated with C. gloeosporioides, were performed along with sensory evaluations. Results: GEOs showed a more effectiveness than GEs and at minimum inhibitory concentration (MIC) lower for oils than those measured to alcoholic extracts. The GEs did not show minimum fungicidal concentration (MCF) against the tested fungi even at the highest concentration tested (6%) in broth medium. GEOs on in vitro conditions showed a better antifungal activity than GEs, indicating that they are more appropriate for incorporation into edible coatings, aiming phytopathogenic postharvest microorganism’s control. When in vitro assessment, the GEO showed a better antifungal activity than the in vivo conducted tests. The P. digitatum fungus was the most sensible to ginger compounds (with lower MIC), followed by A. alternata, F. solani and P. expansum, in this order. These required higher concentrations to attain mycelial inhibition. For tangerines, conventional and nanoemulsion carnauba wax resulted in inferior weight loss compared to control and shellac. There were no differences for gloss measurements for ‘Nova’ mandarins, however, shellac-coated fruit ranked highest for shine in visual sensory assessment. For ‘Unique’ tangors, initially, the shellac coating promoted the highest gloss (shine), but at the end of storage, the nanoemulsion exhibited the highest gloss measurement, although not different from the microemulsion. CO2 and ethanol generally increased and O2 decreased internally during storage for all treatments. The highest levels of CO2 and ethanol were measured in shellac treated samples along with the lowest O2, indicating internal fermentation, with no differences among the other treatments. Shellac and the carnauba microemulsion also altered the volatile profile more intensely than control or nanoemulsion coating, especially for ‘Unique’ tangors. For papaya, all coatings provided some protection, with variations on the effects due to storage conditions and between formulations compositions. Under cold storage, most of analyzes did not resulted in any statistically significant differences among samples. At room temperature and after simulated market conditions the differences become more evident. The nanoemulsions were able to a better maintaining of papaya quality over storage and market conditions. Higher reductions on loss of firmness, color alterations and respiration rate were recorded, with positive action in delaying maturity. No changes in attributes as sweetness, sourness, papaya flavor or the presence of off-flavors related to internal fermentation were reported in the sensory test. The GEO presented some effect in reducing natural diseases on papaya skin, particularly when associated with carnauba, although no action was observed in inhibiting C. gloeosporioides fungal growth after inoculation. Conclusion: GEOs proved to be the most indicated for use as active agents for application in post-harvest fungal control since, in general, they exhibited higher antifungal activity than the alcoholic extracts. The combination of nanoemulsion and GEO into a coating was more effective in vitro experiment than in vivo. For tangerine assays among the coatings tested, the carnauba emulsions resulted in lesser water loss, imparted more sustainable shine, and caused less ethanol production than did shellac. The carnauba nanoemulsion coatings also exhibited higher shine and fewer modifications of the atmosphere and volatiles profile, and consequently assuring a better flavor compared to the microemulsion. Papayas coated with carnauba wax nanoemulsions had the quality preserved over storage and market conditions. The incorporations of GEO into coatings, promoted a reduction of natural diseases on papaya skin, mainly when combined with carnauba.
Descrição
Palavras-chave
Óleo essencial, Nanoemulsão, Cera de carnaúba, Qualidade da fruta, Sensorial, Voláteis de aroma, Essential oil, Nanoemulsion, Carnauba wax, Fruit quality, Sensory, Aroma volatile