Pós-colheita de maçãs tratadas termicamente por imersão em água quente e ultravioleta

Abstract

The demand for fruit free of chemical residues have increased over the years. The adoption of laws that prohibit or limit the use of agrochemicals in the Danish orchards and the elevated incidence of rot in apple (Malus domestica Borkh) storage, encouraged the use of alternative measures aiming at reducing storage rot, resulting in fruits that meet the quality desired by the final consumer. In this study, we adopted the immersion of different apple cultivars (Ingrid Marie and Pinova), derived from a Danish orchard, in different temperatures, with the objective of evaluating the physiological responses in the post-harvest period and the degree of decontamination of the apples during storage. Two different immersion methods were used: manual and automatic. After submitted to the treatments, the apples manually immersed in hot water were used for accompanying the process of internal heating of the fruits. During the storage period, the apples were evaluated by surface color, respiratory rate, mass loss, firmness, soluble solids, physiological disorders and storage rot incidence. Multispectral images and the evaluation of damages caused to the fruits by automatic immersion were also evaluated. We verified that, for cv. Ingrid Marie, the range in temperature between 50 and 54oC for 180 seconds resulted in fruits with higher participation of the color red (elevated a* value), while for cv. Pinova, submitted to the temperature of 50oC, there was higher participation of the color red (higher a* value) and more vivid colors. In the automatic method, the fruits submitted to the temperatures of 54oC for 30 seconds, followed by the application of ultraviolet C resulted in more vivid colors (higher croma value) and higher hue for cv. Ingrid Marie. In relation to the respiratory rate, cv. Pinova showed lower respiration when submitted to 50oC for 180 seconds, while cv. Ingrid Marie showed lower respiration rate when submitted to 52oC for 180 seconds. Fruits from both cultivars treated with the automatic immersion method had lower disease incidence when submitted to the temperature of 54oC for 30 seconds without presenting physical damages and, for the fruits treated manually, the temperature of 50oC for 180 seconds was best for cv. Ingrid Marie and Pinova. The application of the thermal treatments in the automated form was effective, presenting itself as a good option for the producer.