Apple (Malus domestica) is the second largest fruit export crop from New Zealand. Exporters depend on delivering high-quality products to consumers through a complex supply chain. To minimise losses and guarantee that fruit are delivered in prime condition, apples must be picked at optimal maturity prior to storage and shipping. Accurate assessment of apple fruit maturity at harvest is required, since fruit harvested too early or too late are susceptible to physiological disorders or excessive softening during subsequent storage.
Parameters currently used to measure maturity or used as harvest indices are not reliable indicators of storage performance. Comparisons of harvest date and between orchards have shown that other factors must be involved. If testing of new indicative measures could be implemented, orchardists would be able to predict optimal harvest time several weeks in advance and thus arrange their logistical planning. This would also enable informed storage decisions, directing fruit with better storage potential to long-term storage and facilitating earlier marketing for less-optimal batches.
New biomarkers of ‘Royal Gala’ fruit maturity around the harvest period and predictors of high eating-quality value for post storage were identified using a multi-omics study (metabolomics, hormone analysis, enzyme activity analysis, proteomics and transcriptomics) across two seasons. The accuracy of these biomarkers was then tested on two additional seasons in multiple orchards across New Zealand, validating their robustness.
Additional efforts are now being deployed within a new programme, Modelling Markers to Markets, to contribute to building a digital twin of the fresh apple food system, by discovering biomarkers that predict and monitor fruit quality throughout the supply chain. The goal is thus to develop a comprehensive understanding of the effects of pre-harvest environmental conditions and stress tolerance on the biological pathways influencing postharvest fruit quality as ultimately delivered to the consumer.