Abstract

The goal of this study was to use GC-MS and UHPLC-UV-VIS-based metabolomic tools combined with chemometric analysis to discriminate between fruit with blackspot physiological disorder independently of storage condition (regular air or controlled atmosphere) and without blackspot (hereafter referred to as 'Control'). The study looked at polar metabolites, enzymes, fatty acids and oxidative stress markers. Fruit with high levels of lenticel damage are more likely to develop blackspot, which appears to be exacerbated by H2O2 and peroxidation of lipids. Lower catalase (CAT), peroxidase (POD), polyphenol oxidase (PPO), superoxide dismutase (SOD) and phenylalanine-ammonia lyase (PAL) activities together with lower levels of polyphenols (syringic acid, epigallocatechin, quercetin and vanillic) and fatty acids (linolenic, linoleic and palmitic acid), as well as ss-sitosterol, methyl-3-hydroxybutyrate, glyceric acid, hydroxyl butanoic acid, L-threonic acid, hydroxyl glutaric acid and xylose contributed to a higher prevalence of blackspot disorder in stored Hass avocados, which was accompanied by upregulation of soluble proteins. Finally, chemometric analysis revealed a positive relationship between blackspot disorder with gluconic, palmitoleic, galactose oxime, glyceric, hydroxyglutaric, MDA, syringic and oleic acid, as well as a negative relationship with catechin, epigallocatechin, SOD, CAT and tagatose. The study concluded that oxidative stress is the main driver of 'Blackspot' physiological disorder.