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The pitahaya (Hylocereus undatus) is highly perishable and susceptible to chilling injury (CI) The objective of this study was to measure a set of biochemical, physiological, physical-chemical and physical variables in gradually chilling injured pitahaya fruits and assess the degree of correlation of each one with this damage. Pitahayas were stored at 2 or 7±1 °C and 90±6 % RH for up to 30 d, and then held at 22±4 °C and 60±8 % RH for up to 7 d. A visual evaluation of CI was conducted using a five point hedonic scale after storage and transfered to 22 °C. Titratable acidity (TA), total soluble solids, TSS/TA ratio, superoxide dismutase activity (SOD), glutathione activity (GR), piruvate decarboxylase (PDC), alcohol deshydrogenase activity (ADH), weight loss, ethanol content, electrolyte leakage (EL), translucency, hue, chroma, and firmness were analysed in fruit samples. Of which, TA, SOD, ethanol content, EL, and translucency were positively correlated with CI (rs=0.61, 0.65, 0.53, 0.83, and 0.68). [ABSTRACT FROM AUTHOR]

Delayed cooling (conditioning) was evaluated for effectiveness in avoiding chilling injuries of Maciel peaches harvested at two ripeness stages, mature-green or tree-ripe, and immediately thereafter placed in cold rooms at 0°C (controls) or maintained for 2 days (tree-ripe) or 3 days (mature-green) at 20°C before transfer to cold storage at 0°C. After 7, 14, 21 or 28 days, samples were retrieved from storage and kept for 3 more days to complete ripening at 20°C. Delayed cooling mature-green (DCMG) peaches had higher weight losses compared to control mature-green fruit at retrieval from storage and more reduced fresh weight losses after ripening. Peaches harvested at the tree-ripe stage did not differ significantly in weight loss. DCMG peaches were less firm than control mature-green peaches after retrieval from storage. Delayed cooling tree-ripe fruits (CTR) were firmer than controls. No woolliness symptoms were observed in any of the treatments. Flesh browning was determined in all conditioned peaches after 21 or 28 days at 0°C. Leatheriness was observed in all the peaches transferred to air after 21 or 28 days at 0°C. Conditioning of Maciel peaches is not an efficient postharvest procedure to avoid chilling injuries and, therefore, should not be recommended for this cultivar. [ABSTRACT FROM AUTHOR]