No national harvest maturity standards can be provided for Cox apples destined for immediate marketing or for short-term storage. In many cases particular producer or marketing groups have developed their own ‘standards’ in order to supply their retail customers with fruit of a higher sensory quality for a limited period. Such fruit is often referred to as ‘mature’ or ‘tree-ripe’ in order to distinguish this from the different character of Cox harvested earlier and stored for longer periods.
Taste panel studies on Cox were carried out at East Malling in 1980 which showed a decline in firmness, crispness and acidity with later picking, whilst sweetness and aroma increased. Cox apples with an average starch iodine staining pattern of less than 70% (black) or with more than 60% of the sample population containing in excess of 0.1 ppm ethylene, were considered to have developed acceptable eating quality on the tree and were therefore suitable for immediate sale and remained acceptable after 3 months of CA storage.
It is recognised that the storage conditions recommended for apples picked at a stage to provide long storing capability may not be the most appropriate for ‘mature’ or ‘tree-ripe’ fruit. Storage conditions need to be sufficiently stringent to prevent loss of firmness and background colour but should not induce abnormal metabolism.
Late-picked Cox apples are more likely to develop low temperature breakdown and alcoholic off-flavours in CA storage than those harvested earlier. Particular care should be taken over the monitoring of fruit quality in store.
There is a need to develop standards for harvest maturity parameters for Cox and other dessert apples intended for immediate sale. This would prevent fruit of unacceptable eating quality being supplied to the markets. Additionally harvest maturity standards are required for ‘tree-ripe’ fruit that provide acceptable eating quality for storage period of 2-3 months. Research is required to identify optimum conditions for the storage of fruit picked at advanced stages of maturity.