Changes in ATP, ADP and pyridine nucleotide levels related to the incidence of physiological disorders in 'Conference' pears and 'Jonagold' apples during controlled atmosphere storage

The effects of four controlled atmosphere (CA) storage conditions on ATP an d ADP levels, and the concentrations of NAD(H) and NADP(H) were investigate d in relation to the incidence of physiological disorders of 'Conference' p ears and 'Jonagold' apples during six months at 0 degrees C (+/-0.5 degrees C). ATP concentrations in apple and pear fruits stored in CA were lower th an those in air-stored fruits but their reduction was lowest for 'Conferenc e' pears stored in 1.5% CO2 + 1.5% O-2 'Jonagold' apples showed a sharp dec rease followed by a slight increase in the ATP levels at the beginning of t he second month of storage. The concentrations of NADH and NADPH in the tis sues of 'Conference' pears and 'Jonagold' apples increased in both CA- and air-stored fruits. In contrast, the oxidized nucleotides, NAD and NADP, gen erally decreased with storage time and no significant differences between t he treatments were found. Only 'Conference' pears, when stored in 6% CO2 0.5% O-2, exhibited a strong decline in NADP levels, which was associated w ith the low metabolic activity due to the high incidence of disorders. No p hysiological disorder was noted in 'Jonagold' apples during the six months of storage time, while 'Conference' pears exhibited disorders such as flesh browning, brown heart and cavities in all CPI-storage conditions. Severity of these disorders depended on CA-conditions and length of storage. For 'C onference' pears the CA-combination of 1.5% CO2 + 1.5% CO2 seemed to be mos t promising since it resulted in very low percentage of damaged fruits. A p robable relationship between energy level expressed by ATP concentrations, ATP:ADP ratios and pyridine nucleotides and the development of these disord ers is discussed.