Fruit maturity and vapour heat treatment influence ‘flesh cavity with white patches’ disorder in ‘Calypso™’ mango

Abstract

‘Calypso™’ mango was developed in Australia and is an important export cultivar. However, it can express internal disorders (IDs) after postharvest vapour heat treatment (VHT), a prerequisite phytosanitary protocol for export. IDs negatively influence consumer satisfaction, including repeat purchase. The incidence and severity of fruit disorders are typically influenced by genetic, environmental, and management factors, with harvest maturity being generically important. Fruit was sampled at a commercial VHT facility for nine export case study supply chains. Half of the fruit were maintained as untreated controls, while the other half were subject to VHT. Fruit maturity was assessed individually as % dry matter (DM) by means of a hand-held near-infrared reflectance (NIR) spectrometer. Thereafter, fruit were held at 20-22°C and ~90% relative humidity (RH) until the eating ripe stage as determined by hand firmness. Each fruit was then cut and visually assessed for incidence and severity of IDs. Fruit maturity in the different supply chains and within each harvest batch varied up to range of 14.4 to 19.9% DM. A disorder termed ‘flesh cavity with white patches’ (FCWP) was consistently elicited by VHT. Its expression was negatively correlated (r=-0.51) with fruit maturity at harvest, whereby relatively ‘less mature’ fruit were more prone to FCWP post-VHT. Thus, incidence and severity of FCWP could prospectively be minimised by harvesting and/or sorting for DM prior to VHT.