Efeitos dos métodos hidrotérmicos, radiação ultravioleta e revestimento na preservação pós-colheita de pitaia (Selenicereus undatus) durante o armazenamento refrigerado

Abstract

Dragon fruit holds significant marketing potential and the challenge lies in the limited understanding of effective technologies to extend its quality and shelf-life. In this context, this study aimed to assess the impact of traditional and innovative technologies on the postharvest of dragon fruit prior to cold storage. Hot water treatments at 49 and 51 °C combined with calcium chloride (CaCl2) were administered, and subsequently, the fruit were stored at 7 °C for 38 days. As innovative technologies, the effects of ultraviolet radiation (UV), including UV-B and UV-C, and the application of biodegradable coatings were explored. The individual and combined impacts of ultraviolet treatments (UV-B and UV-C) at various doses (UV-B: 1.17, 2.33, 3.50, and 4.67 kJ/m2; UV-C: 4.08, 8.17, 12.25, and 16.33 kJ/m2; and UV-B+UV-C: 10.50 kJ/m2) were evaluated for 33 days in fruit stored at 7 °C. The efficiency of corn starch coatings 3% (ST), corn starch 3% combined with Aloe vera gel (ST+AV), and Aloe vera gel alone (AV) was also assessed. The coated dragon fruit were stored for 24 days at 5 °C. All experiments involved exposing the fruit to ambient conditions after the refrigeration period. The results demonstrated that the combination of high temperatures with CaCl2 was effective in maintaining the postharvest quality of dragon fruit for an extended period and inducing chilling tolerance. Lower decay index, mass loss, color changes, respiratory rate, malondialdehyde content, and electrolyte leakage were observed in treated fruit. The response of dragon fruit to ultraviolet radiation was dose-dependent. UV-B radiation at 1.17 kJ/m2 exhibited a greater ability to maintain dragon fruit quality, reducing deterioration, respiratory rate, electrolyte leakage, and preserving its characteristic color. UV-C radiation doses beyond 4.08 kJ/m2 had a negative impact on dragon fruit postharvest, resulting in peel color degradation with subsequent yellowing. Fruit coated with starch-based coatings showed lower mass loss, higher soluble solids content, higher acidity, and better maintenance of firmness compared to uncoated fruit. The combination of starch coating with Aloe vera gel revealed superior potential in preserving the dragon fruit's visual appearance, while fruit coated only with Aloe vera gel exhibited higher deterioration and shortened postharvest life.