Qualidade pós-colheita de tomates 'Débora' com utilização de diferentes coberturas comestíveis e temperaturas de armazenamento Quality of 'Debora' tomato using different edible coatings and storage temperatures

Este estudo visou avaliar o efeito de diferentes coberturas comestíveis sobre a qualidade pós-colheita do tomate de mesa cv. Débora. Foram utilizadas as seguintes coberturas: cera de carnaúba Fruit Wax H2 (18%), emulsão de resinas Fruit Wax M-AC (18%) e cera de carnaúba Megh Wax ECF-124 (18%); tomates sem cera serviram de controle. Foram utilizados 40 frutos por tratamento em delineamento inteiramente casualizado. Após a limpeza e aplicação das ceras, os frutos foram armazenados a 12,5&deg;C e 25&deg;C e 90% de umidade relativa. Análises para perda de massa fresca (%), coloração e qualidade foram realizadas durante quinze dias. No final do período de armazenagem, os frutos foram avaliados quanto à firmeza, pH, concentração de sólidos solúveis, vitamina C e acidez. Foi realizada também análise sensorial para frutos armazenados nas duas diferentes temperaturas. O tratamento com Megh Wax ECF-124 proporcionou menor perda de massa e frutos mais firmes em ambas as temperaturas. Tomates tratados com Fruit Wax M-AC e Megh Wax ECF-124 apresentaram maior porcentagem de frutos apropriados ao consumo. Não houve diferença significativa entre os tratamentos quanto à coloração e análises químicas, exceto para os frutos cobertos com Fruit Wax M-AC, que apresentaram menor teor de vitamina C em ambas as temperaturas e maior pH a 25&deg;C. As ceras Fruit Wax M-AC e Megh Wax ECF-124 não interferiram no sabor e no odor dos frutos. A aplicação de cera contribui para uma diminuição na perda de massa e decréscimo no número de frutos descartados devido a danos físicos e podridões, sendo que Megh Wax ECF-124 é mais eficiente na manutenção da qualidade de tomates de mesa.<br>This study aimed at evaluating the effect of edible coatings on tomato cv. Debora post-harvest quality. The following waxing emulsions were used: wax of carnauba Fruit Wax H2 (18%), emulsion of resins Fruit Wax M-AC (18%) and wax of carnauba Megh Wax ECF-124 (18%); tomatoes without wax were used as reference. A totally randomized experiment was installed using 40 fruits for each treatment. After cleaning and application of the waxes, the fruits were stored at 12,5&deg;C and 25&deg;C and 90% RH. Analyses for weight loss (%), color and quality were carried out during fifteen days. After storage, fruits were evaluated for firmness, pH, soluble concentration of solids, vitamin C, total acidity and a sensorial analysis. Tomatoes treated with Megh Wax ECF-124 presented minor weight losses and firmer fruits in both temperatures. Fruits treated with Fruit Wax M-AC and Megh Wax ECF-124 showed the highest percentage of fruits edible for consumption. There was no significant difference between treatments for color and chemical analyses, except for fruits covered with Fruit Wax M-AC, that showed low level of vitamin C on both temperatures and higher pH level at 25&deg;C. Fruit Wax M-AC and Megh Wax ECF-124 did not affect flavor and odor on fruits. Wax application contributed to reduce weight loss and the number of fruits discarted due to physical damage and diseases. Megh Wax ECF-124 was the most efficient wax for keeping fruit quality

The Bacteriophage Head-to-Tail Interface

International audienceMany icosahedral viruses use a specialized portal vertex for genome encapsidation in the viral capsid (or head). This structure then controls release of the viral genetic information to the host cell at the beginning of infection. In tailed bacteriophages, the portal system is connected to a tail device that delivers their genome to the bacterial cytoplasm. The head-to-tail interface is a multiprotein complex that locks the viral DNA inside the phage capsid correctly positioned for egress and that controls its ejection when the viral particle interacts with the host cell receptor. Here we review the molecular mechanisms how this interface is assembled and how it carries out those two critical steps in the life cycle of tailed phages