Physiological disorders, bitter rot and other fungal decay of ‘Aroma’ apple fruit stored in controlled atmosphere

Abstract

ABSTRACTEffects of controlled atmosphere (CA) conditions on physiological disorders and fungal fruit decay on apple ‘Aroma’ were investigated. Fruit from three growing seasons were stored at 1% or 2% O2 (both at 2% CO2) at either 1°C or 3°C in small research units; controls were kept in the same ventilated rooms at the two temperatures (ambient air). The fruit were removed from storage after four or six months and assessed for fruit decay immediately afterwards and after two weeks at 20°C. Fruit quality parameters were recorded at the end of storage. On a three-year average, fruit stored in CA was less ripe at the end of storage. After both four and six months storage, CA reduced total decay (physiological disorders and fungal decay) by on average 70% and 45%, respectively, compared to storage in ambient air. Senescent breakdown was lower after CA storage for four months, but not after six months and not after simulated shelf life. Soft scald was lower when stored in CA both after cold storage at 1°C and simulated shelf life. After storage at 3°C there was lower incidence of soft scald when stored in CA after four months, but not after six months. For fungal fruit decay in general, there was no effect of low oxygen, however, 2% O2 gave slightly less bitter rot (Colletotrichum acutatum) than 1% O2 and significantly less than ambient air after simulated shelf life. Averaged over all oxygen levels, 1°C gave significantly less bitter rot than 3°C. It may be concluded that use of CA for storage of ‘Aroma’ is a good way of reducing development of physiological disorders. However, development of bitter rot seemed to be more influenced by temperature and storage time than by low O2.