Postharvest Cold-Storage Behaviour of ‘Nadorcott’ Mandarin Fruit Remains Unaffected by Preharvest Shade Netting

Abstract

During postharvest cold storage, fruit sustains physical and biochemical changes, which may result in physiological rind disorders that consequently affect the fruit’s marketability. Preharvest conditions are known to affect postharvest fruit quality, with the effect of preharvest shade netting being currently unknown. To this end, ‘Nadorcott’ mandarin (Citrus reticulata Blanco) fruit, grown under shade netting and without it, was harvested during two consecutive seasons from an orchard in Citrusdal, Western Cape, South Africa. The fruit was evaluated prior to, as well as after a 7-day shelf-life period following cold storage at either −0.6 or 4 °C for 14, 27 and 34 days, respectively, for changes in rind and pulp colour, rind carotenoids, soluble solid content (SSC), citric acid content and SSC/citric acid ratio. Weight loss and the incidence of rind physiological disorders (staining) were also recorded. The results showed that shade net did not affect the storage behaviour of the fruit, as no treatment differences were seen. However, a storage duration effect for both treatments was evident in some internal and external quality parameters, viz., weight loss percentage and carotenoid content increased over the storage duration. Inconsistency regarding the storage duration effect on the rind colour, SSC and acid content were evident between seasons, at both temperatures. Staining only occurred in the first season after 34 days at both temperatures. The results indicated that shade netting had no negative effect on the cold-storage behaviour of ‘Nadorcott’ fruit. However, contrasting findings from this study emphasized that the condition of the fruit at harvest plays a significant role in the postharvest behaviour of the fruit during cold storage, and different growing conditions may also be a contributable factor.