RESUMEN
This study aimed to evaluate the effect of different levels of relative humidity (RH) on the maintenance of Postharvest quality of 'Niagara Rosada' table grapes after cold storage at 0.5°C for 21 days. A completely randomized design was used, with five replicates of 18 clusters per treatment. The selected levels of relative humidity were 85, 90, 95 and 100%, obtained by means of electronic humidity controllers. The fruits were evaluated in relation to rot incidence, berry cracking, browning rate, respiratory rate, titratable acidity, soluble solids, resistance to abscission, berry drop and weight loss. The evaluations were assessed at 20 days of storage and after two and four days of shelf-life (20°C; 85% RH). The results showed that as higher as relative humidity, higher is rot incidence and that the variables rachis browning and weight loss were inversely related to relative humidity. Resistance to abscission at the end of storage was higher when humidity ranged between 90 and 95%, but it was not affected after transfer to shelf-life from cold storage. Relative humidity ranging between 90 and 95% offer the best conditions to maintain the Postharvest quality of 'Niagara Rosada' table grapes.
Este trabalho teve como objetivo avaliar o efeito de diferentes níveis de umidade relativa (UR) sobre a manutenção da qualidade pós-colheita de uvas de mesa 'Niagara Rosada', após armazenamento sob refrigeração, a 0,5°C durante 21 dias. Foi utilizado delineamento inteiramente casualizado, com cinco repetições de 18 cachos por tratamento. Os níveis de umidade relativa utilizados foram 85, 90, 95 e 100%, conseguidos com o auxílio de controladores eletrônicos. Os frutos foram avaliados quanto à incidência de podridões e rachaduras, índice de escurecimento, taxa respiratória, acidez titulável, sólidos solúveis, resistência ao degrane, degrane e perda de massa. As avaliações foram realizadas aos 20 dias de armazenamento e após dois e quatro dias de exposição dos frutos à condição ambiente (20°C; 85% UR). Os resultados indicaram que quanto maior o teor de umidade, maior a incidência de podridões, e que as variáveis escurecimento da ráquis e perda de massa possuem relação inversa à umidade relativa. A resistência ao degrane na saída da câmara foi maior com umidade entre 90 e 95%, mas não foi afetada após a transferência dos cachos à condição ambiente. O armazenamento sob refrigeração e umidade relativa na faixa de 90 a 95% proporciona melhor manutenção da qualidade pós-colheita de uvas 'Niagara Rosada'.
RESUMEN
Several postharvest diseases of table grapes (Vitis vinifera) occur during storage, and gray mold rot is a particularly severe disease because the causal agent, Botrytis cinerea, grows at temperatures as low as 0degrees C. Other postharvest diseases, such as those caused by Penicillium spp. and Aspergillus spp., also often lead to deterioration in the quality of table grapes after harvest. The use of plant essential oils such as thymol and linalool, to reduce postharvest diseases in several kinds of fruits, including table grapes and oranges, has received much attention in European countries. However, to the best of our knowledge there has been no report of the use of thymol fumigation to control gray mold in table grapes in Korea. Thymol (30 microg/mL) and linalool (120 microg/mL) significantly inhibited mycelial growth and conidia germination of B. cinerea. The occurrence rate of gray mold rot of B. cinerea and other unknown fungi was significantly reduced by fumigation with 30 microg/mL thymol in several table grape cultivars, such as Campbell early, Muscat Bailey A, Sheridan, and Geobong. In this study, fumigation with 30 microg/mL thymol, had no influence on the sugar content and hardness of grapes, but reduced fungal infection significantly. This suggests that 30 microg/mL thymol could be utilized to reduce deterioration of grapes due to gray mold and other fungal infections during long-term storage.