Controlled atmosphere storage of ‘Granny Smith’ apples

Abstract The effect of controlled atmosphere (CA) regimens on the storage quality of ‘Granny Smith’ apples has been examined over two seasons. Fruit quality was assessed by physical parameters, incidence of storage disorders and sensory evaluation. There were small differences in fruit quality between 2% O 2 /2% CO 2 and 3% O 2 /3% CO 2 atmospheres, with slight advantages of 2% O 2 /2% CO 2 in terms of titratable acidity. A 2% O 2 5% CO 2 atmosphere resulted in fruit of the same firmness as those in 2% O 2 /2% CO 2 , although titratable acid levels were lower. Compared with 2% O 2 /2% CO 2 , fruit from a 1% O 2 / 1.5% CO 2 atmosphere were not significantly firmer or more acid. Low (0.75%) CO 2 concentrations with either 2% or 3% O 2 resulted in softer fruit, suggesting that moderate levels of CO 2 are important for maintenance of flesh firmness. Fruit from 2% O 2 / 0.75% CO 2 atmospheres were also less green than fruit from 2% O 2 % CO 2 , but there was no effect of CO 2 on colour when O 2 levels were 3%. Low CO 2 concentrations resulted in a high incidence of coreflush and flesh browning. Sensory analysis did not detect differences between fruit from any of the CA treatments except 2% O 2 /0.75% CO 2 , which had the lowest acidity, lowest juiciness, and less overall acceptability.