The postharvest preservation of apples indicated that well-preserved varieties of apples had increased superoxide dismutase (SOD) activity initially, and the activity declined during later storage as apples deteriorated. The increased SOD activity linked to better preservation correlated with higher phenolic content and free-radical scavenging-linked antioxidant activity. Well-preserved varieties were able to maintain a more stable pentose phosphate pathway (measured by the activity of glucose-6-phosphate dehydrogenase) throughout the storage period. Proline content increased with proline dehydrogenase (PDH) activity in the initial storage period, indicating proline catabolism supporting potential adenosine 5′-triphosphate (ATP) synthesis. During later storage, succinate dehydrogenase activity increased, while PDH activity declined indicating a shift to tricarboxylic acid cycle and likely nicotinamide adenine dinucleotide hydrogen (NADH) generation for ATP synthesis. This shift, coupled with the declining SOD activity, coincides with rapid deterioration. The guaiacol peroxidase activity generally declined in late stages, indicating postharvest deterioration
