Diurnal Harvest Cycle and Sap Composition Affect Under-Skin Browning in ‘Honey Gold’ Mango Fruit

Abstract

Under-skin browning (USB) is an unsightly physiological disorder that afflicts ‘Honey Gold’ mango fruit. Under-skin browning symptoms develop after harvest upon the interaction of physical abrasion and physiological chilling stresses. Less understood preharvest and/or harvest factors may also influence fruit susceptibility to USB. In this study, we examined the impact of harvest time during the diurnal cycle and fruit sap components on USB development. Fruits were harvested at 4- to 6-h intervals, lightly abraded with sandpaper to simulate vibration damage during refrigerated road transport, held at 12 ± 1°C for 6 days, transported to the research facilities and ripened before USB assessment. Spurt and ooze sap from the fruit were collected at each harvest time. The samples were separated and analysed by gas chromatography–mass spectrometry. Fruit harvested at 10:00, 14:00 and 18:00 h had 3- to 5-fold higher incidence of USB than did those picked at 22:00, 2:00 and 6:00 h. Sap concentrations of the key aroma volatile compounds 2-carene, 3-carene, α-terpinene, p-cymene, limonene and α-terpinolene were higher for fruit harvested at 14:00 h compared to those picked at other times. In the fruits harvested in the afternoon, abraded skin treated with spurt sap sampled at 14:00 h had 14.3- and 29.0-fold higher incidence and severity, respectively, of induced browning than did those treated with sap collected at 6:00 h. The results showed that fruit harvested in the afternoon were more susceptible to USB than those picked at night or in early morning. The diurnal variation in fruit sensitivity was evidently associated with specific compositional differences in sap phytotoxicity. Topical application to the fruit skin of pure terpinolene and limonene resulted in induced USB damage, whereas pure carene and distilled water did not. Microscopy examination showed that while skin damage caused by pure terpinolene and limonene was not identical to USB per se, similarities suggested that sap components cause USB under inductive commercial conditions. Considered collectively, these findings suggest that night and early morning harvesting will reduce USB and thus improve the postharvest quality of Honey Gold mango fruit.

Investigation of indoor total volatile organic compound concentrations in densely occupied university buildings under natural ventilation: Temporal variation, correlation and source contribution

“…Here, fruits, biscuits and drinks were offered, which were identified as one of the most important sources of indoor VOCs, such as limonene. 26 Furthermore, the outdoor TVOC concentrations were relatively steady throughout the whole year, as shown in Figure 2; it ranged from 176 µg/m³ to 251 µg/m³, which was consistent with reported results of a previous study. 27…”

“…Here, fruits, biscuits and drinks were offered, which were identified as one of the most important sources of indoor VOCs, such as limonene. 26 Furthermore, the outdoor TVOC concentrations were relatively steady throughout the whole year, as shown in Figure 2; it ranged from 176 mg/m 3 to 251 mg/m 3 , which was consistent with reported results of a previous study. 27 Furthermore, variations in TVOC concentrations over three seasons and two building types in six typical rooms (L3, L4, L9, C11, C12 and C16) were analysed during the whole occupied period, as shown in Figure 3.…”

Postharvest factors affect under‐skin browning in ‘Honey Gold’ mango fruit

“…To test potential differences in damage on fruit collected at different times of day, 0.1 mL aliquots of either spurt sap or upper-phase spurt sap collected either in the morning (08:00) or in the afternoon (14:00) were spotted onto four areas of each fruit that had been abraded as described above. 8 Distilled water (0.1 mL) and terpinolene (0.05 mL; Sigma-Aldrich Inc., USA) were used as negative and positive controls, respectively. A rectangular piece (~1 cm 2 ) of filter paper was placed atop each treated area and then covered with a piece of aluminium foil (~1.5 × 2.3 cm) secured with plastic tape to minimise vaporization.…”

“…A rectangular piece (~1 cm 2 ) of filter paper was placed atop each treated area and then covered with a piece of aluminium foil (~1.5 × 2.3 cm) secured with plastic tape to minimise vaporization. 8 Fruit were then transported to the research facility as described for experiment 1, abraded as described for experiment 2 and then held at either 12 or 20°C for 8 days followed by removal of the foil and filter paper patches. Then, the fruit were ripened as described for experiment 1.…”

“…This is associated with differences in sap phytotoxicity. 8 Given that USB also involves browning discolouration of the skin, the possible association between sap and USB warranted investigation.…”