Qualidade pós-colheita de pitombas in natura submetidas a diferentes temperaturas, embalagens e doses de radiação UV-C

Abstract

The fruits of the pitombeira have great acceptance by man and fauna, the pulp is succulent, sweet, lightly acidic and of pleasant flavor, and can be consumed in natura. Therefore, this work aims to evaluate the postharvest attributes of pitomba subjected to different temperatures, packaging and doses of ultraviolet radiation C (UV-C), verifying the quality variables: physical, chemical, physicochemical and bioactive. To verify the combined effect of temperatures, packaging and the storage time, in the postharvest conservation of pitomba, a completely randomized design was used in a 5x5x7 triple factorial scheme for physical, physicochemical and chemical, and 5x5x4 for the bioactive analyses (temperatures x packages x days), with 3 replications and 10 fruits per repetition. Being five temperatures: 6°C, 8°C, 10°C, 12°C and 14±1°C to 75±5% of relative humidity (RH) and five packages: polypropylene (PP); low densitypolyethylene (LDPE); polyethylene terephthalate (PET); polyvinyl chloride (PVC) + expanded polystyrene (EPS) and without packaging (control), the evaluation was performed every 2 days, in a period of 12 days (0, 2, 4, 6, 8, 10 and 12 days), while the bioactive analyseswere performed every 4 days (0, 4, 8 and 12 days). Evaluating the effects of UV-C radiation and storage time, in the postharvest conservation of pitomba, a completely randomized design was used in a 5x8 double factorial scheme (radiation doses x days) with 3 replications and 10 fruits per repetition. The treatments were determined as to the exposure of the fruits to the irradiating source, constituting: the control 0.00 Kj m-2 (0 min); 0.60 Kj m-2 (1 min); 1.21 Kj m-2 (2 min); 2.42 Kj m-2 (4 min) and 4.84 Kj m-2 (8 min), with wave amplitude measuring 254 ηm. The installation of the experiment consisted of the packaging of the fruits irradiated in low density polyethylene (LDPE), stored at 6±1°C in BOD incubator with 75±5% relative humidity (RH). The fruits were analyzed every 2 days regarding physical, chemical, physicochemical and bioactive characteristics, for 14 days (0, 2, 4, 6, 8, 10, 12 and 14 days), except for the postharvest conservation that, in both experiments, the pitombas were evaluated by higher period, depending on their commercial quality. Were evaluated: mass loss, postharvest conservation, peel firmness, soluble solids (SS), titratable acidity (TA), maturation index (SS/TA), staining: (L*, °hue and chroma), hydrogenionic potential (pH), pulp/peel ratio, pulp/seed ratio, respiratory rate (RT), vitamin C (ascorbic acid), antioxidant activity (ATA) and phenolic compounds (FC). The data obtained with the respective analyses were subjected to analysis of variance (P≤0.05) and, when significant, the averages were compared by the Scott-Knott test and regression at level 5% of significance. In the conditions under which the experiments were carried out, the results allow us to conclude that the LDPE packaging, combined with the temperature of 6°C, ensured the lower mass loss, besides providing the fruit increment in the postharvest conservation, for up to 16 days. As for the experiment with UV-C, it was concluded that the doses of 0.60 and 1.21 kJ m-2 showed promising in the postharvest conservation of pitomba, by contributing significantly for the phenolic compounds, ascorbic acid stability, better antioxidant capacity and lower mass loss, besides being responsible for maintaining desirable postharvest characteristics, allowing fruit preservation for up to 22 days.