Postharvest changes in internal fruit quality in apples with sunburn browning.

摘要

Postharvest changes in flesh firmness, soluble solids concn. (SSC) and titratable acidity (TA) associated with increasing severity of sunburn browning of apples were investigated in regular atmosphere cold storage. In 2005, cv. Gala apples were harvested at maturity and sorted into 5 classes ranging from no sunburn (Sb-0) to severe sunburn browning (Sb-4). Flesh firmness, SSC and TA were measured on flesh tissue beneath the sunburned area of apples at harvest and at monthly intervals for 6 months.In 2006, a similar protocol was used for cv. Gala, Golden Delicious, Jonagold, Granny Smith and Fuji apples, except that these fruit quality traits were determined at harvest and after 3 and 6 months in regular atmosphere cold storage. Flesh firmness andSSC increased, but TA decreased both yr in all cultivars as sunburn severity increased from Sb-1 to Sb-4. Patterns of higher firmness with more severe sunburn browning persisted during cold storage even though firmness in all classes of fruits decreasedgradually with time in cold storage. Patterns of lower TA as severity of sunburn increased also persisted during cold storage, but TA declined more markedly in apples with more severe sunburn. The ratio of SSC to TA (SAR) increased as the severity of sunburn increased in all cultivars. SAR also increased markedly from harvest to 3 and 6 months after harvest with ratios exceeding 200 in Sb-4 of some cultivars after 6 months storage. This occurred because TA declined very markedly as time in cold storageincreased. Relative water concn. of tissue in sunburned areas of apples declined as the severity of sunburn increased, and helped to account for the higher SSC and firmness observed in sunburned apples.