Vida útil e qualidade pós-colheita de atemoia ‘Thompson’ em função da radiação UV-C, absorvedor de etileno e cloreto de cálcio

Abstract

The postharvest life of the anonaceae is limited by physiological deterioration, caused by the excessive ripening of the fruit and the development of pathogens that cause rot, while at the same time the senescence of the fruits is characterized by a rapid browning and softening of the skin. The aim of this study was to evaluate the storage and postharvest characteristics of 'Thompson' atemoya submitted to: different doses of UV-C radiation, presence or absence of ethylene absorber and calcium chloride concentrations. Two experiments were carried out in a completely randomized design (DIC), the first with a 4x2x6 triple factorial scheme (doses of UV-C radiation x ethylene absorber x storage time) and the second in a 4x6 double factorial (calcium chloride x storage time), with four repetitions and one fruit per repetition for both experiments. In the first experiment, the fruits were exposed to different doses of UV-C radiation (0; 1,131; 2,263 and 3,394 kJ m-2), stored in low density polyethylene (LDPE) packages, in the presence or absence of the ethylene absorber (potassium permanganate sachet). For the second experiment, the effect of fruit immersion in four concentrations of calcium chloride (CaCl2) was evaluated: 0%, 2%, 4% and 6% CaCl2. In both experiments, the treated fruits were stored refrigerated, in a B.O.D. at 15 ± 2 °C and 70 ± 5% RH, for 15 days, being sampled at 0, 3, 6, 9, 12 and 15 to determine the chemical, physicalchemical and bioactive attributes. The evaluated parameters were: loss of mass, firmness, soluble solids, titratable acidity, maturation index, hydrogenionic potential, coloring (luminosity, ºhue, chroma and browning rate) and ascorbic acid for both experiments; in addition to antioxidant activity and total extractable polyphenols, for the first, and respiratory rate, for the second experiment. For the first experiment, the data were subjected to principal component analysis (PCA) and cluster analysis, using the method of grouping distance averages (UPGMA) and as a measure of dissimilarity to Euclidean distance. For the second experiment, analysis of variance (P≤0.05) was performed and, when significant, regression analysis was performed. The application of the analysis of the main components, in the first experiment, by the presentation of the PCs 1 and 2, which explained 57.09% of the data variation, and the cluster grouping analysis, allowed the characterization and differentiation between the analyzed treatments, with the formation of 5 groups, formed mainly by the days of analysis, in which it was found that until the sixth day the fruits maintained the appropriate characteristics after harvest, regardless of the treatments applied. There was no effect of exposure of fruits to UV-C radiation, however, the lower doses promoted greater maintenance of the color of the atemoya for a longer time, providing the fruits with better appearance in storage. The presence or absence of the ethylene-absorbing sachet did not affect the quality characteristics of atemoia during the storage period. The immersion of the fruits in a 6% calcium chloride solution is a viable and economical alternative for maintaining the quality of atemoia in natura, mainly in the preservation of the color and loss of mass, delaying the senescence of the fruits. Under these conditions, the fruits can be kept for up to 15 days under refrigeration (15º C) for commercialization and consumption. In the case of other concentrations (0%, 2% and 4%), the fruits maintained adequate characteristics for commercialization until the 12th day of storage.