This study was carried out to identify the mineral attributes in the flesh and skin tissues better related to bitter pit severity in 'Fuji' apples. 'Fruit were harvested in a commercial orchard in Southern Brazil (Lages, SC), and left for four months in conventional cold storage (at 0±0.4ºC and 90-95% RH). Subsequently, fruits were divided into four lots according to the level of bitter pit severity: none (0 pit/fruit), low (1-2 pits/fruit), moderate (3-4 pits /fruit), and high (5-16 pits /fruit). There were 15 fruit replicates for each level of bitter pit severity. Mineral analysis of Ca, Mg, K, and N in the skin and in the flesh tissues were performed on individual fruits of each severity level. The univariate analysis in the fresh tissue showed an increase of K content and of the K/Ca ratio with the increase of bitter pit severity, despite of no difference of Ca contents. In the skin, Ca and N contents reduced, and K/Ca, Mg/Ca, and (K+Mg)/Ca ratios increased with the increase of bitter pit severity. However, the canonical discriminant analysis (multivariate analysis) showed that the best segregation between levels of bitter pit severity was achieved with the Ca content in the skin. Therefore for 'Fuji' apples, it is safer to predict the occurrence of bitter pit during cold storage by assessing the Ca content in the skin rather than the in flesh. Fruit with Ca content in the skin < 240 mg kg-1 of fresh matter are susceptible to bitter pit.
Malus domestica; fruit quality; mineral nutrition; physiological disorder; multivariate analysis
