Kiwifruit and apple are by far the two largest fruit export crops from New Zealand. Both species are harvested at maturity and can then be stored for a long periods of time at chilling temperatures. Delivering high quality product is the major issue for New Zealand fresh fruit exporters. Fruits must have good storage performance to reduce losses and ensure perfect quality for delivery to the consumer.
One of the most important factors affecting good storage is ensuring fruit are at the correct maturity at harvest. Soluble solids content (SSC) has been used as a measure of maturity and as a harvest index for kiwifruit in New Zealand since 19801. However, attainment of a minimum SSC is not a reliable indicator of storage performance, and comparisons of harvest date and between orchards have shown that other factors must be involved. New measures have to be found to provide a strong prediction of maturity and storage performance. With these new measures, fruit lines with good storage potential will be channelled into longer term storage and lines with less storage potential will be marketed earlier. The aim of this project is so to identify new biochemical attributes of fruit to give an improved determination of maturity at harvest and a strong predictive value for eating quality post storage.
Gold kiwifruit (Gold3) and apple (Royal Gala) from four different vines and trees respectively, were harvested at four different times, each two weeks apart, with Harvest 3 corresponding to commercial harvest. LC-MS based metabolomics analysis combined with multi-statistical analysis has been carried on both species to get an overview of fruit metabolism according to harvest time. Clear differences in metabolic fingerprint can be observed between each harvest time for both type of fruit. The important metabolites responsible for the discrimination have been identified. Related metabolic pathways were identified and tests of corresponding transcripts and enzyme activities are in progress.