Conditioning for other dessert varieties
Conditioning Cox apples stored in ULO conditions by raising store oxygen concentrations 4-5 weeks before opening the store is effective in enhancing flavour. In Gala apples increasing the store oxygen from 1% O2 to ambient (21%) concentrations part way through a 4-month storage period is reported to have increased the emission of some of the volatiles contributing to aroma. No additional losses of firmness, titratable acidity or soluble solids content were detected after storage in ‘dynamic’ conditions.
Recent research has shown potential benefit of enhanced aroma production in CA-stored Fuji and Granny Smith apples by short-term exposure to hypoxic (low oxygen) treatments. The hypoxic treatment (<0.5% O2) applied for 1 day enhanced subsequent ester production possibly by providing ethanol as a precursor for ester synthesis.
1. Further work is required on UK cultivars to compare the effectiveness of hypoxic and anoxic (high oxygen) and ‘dynamic’ treatments for amelioration of low aroma production in apples after long-term storage.
Since the distinctive aroma component of Cox apples segregates as though determined by a single dominant gene, it should be possible to breed new selections with improved storage potential and conserved Cox aromatic flavour. Cultivar improvement would reduce the reliance on stringent CA conditions to retard ripening and quality loss during storage with the prospect of enhanced aroma production.
2. More rapid selection techniques are required to screen for flavour and further genetic studies might result in convenient marker genes being identified that can be used as assays for flavour at an early stage.