Impaired aroma production of CA-stored ‘Jonagold‘ apples as affected by adenine and pyridine nucleotide levels and fatty acid concentrations

Abstract

SummaryPreclimacteric ‘Jonagold’ apples were stored for up to six months following two fruiting seasons. Storage was at 0°C in air (control) and various controlled atmosphere (CA) conditions. Fruits kept under CA-storage produced less aroma volatiles than air-stored fruits. This suppression of aroma volatiles was accentuated with increasing storage duration. Greatest impairment was caused by very low oxygen (0.5% O2) combined with high CO2 (6%) concentrations. Respiration rate was inhibited to a similar degree as the emission of aroma volatiles. There were lower ATP concentrations in fruits kept under CA-storage, thereby decreasing the ATP:ADP ratio and energy charge of tissues. On the other hand, concentrations of NADPH and NADH increased in CA as well as in air stored fruits. However, there were no significant differences between CA-treatments. Moreover, no correlations between NADPH or NADH concentrations and volatile aroma or fatty acid production were found. For that reason pyridine nucleotides are not considered to be of regulatory significance. CA storage caused an overall decrease in the concentrations of free- and esterified fatty acids. These acids are considered the dominant precursors of volatile aroma substances in apples. Suppressed aroma production appeared to be highly correlated with the concentration of free linoleic acid. Impaired aroma production of ‘Jonagold’ apples was apparently related to lower ATP concentrations and decreased fatty acid biosynthesis under CA-storage.