Flesh browning in ‘Rocha’ pear as affected by fruit mineral composition and controlled atmosphere conditions

ABSTRACT

The aim of this study was to evaluate the effect of controlled atmosphere (CA) conditions and mineral contents on flesh browning in ‘Rocha’ pear. The fruits were stored at different CA conditions: 0.5 kPa O₂ + < 0.03 kPa CO₂; 1.0 kPa O₂ + < 0.03 kPa CO₂; 1.0 kPa O₂ + 1.0 kPa CO₂; 1.0 kPa O₂ + 2.0 kPa CO₂ and 1.0 kPa O₂ + 3.0 kPa CO₂. Fruit were evaluated for incidence and severity of flesh browning after 9 months of storage (−0.5 ± 0.1 °C and 96 ± 2% RH). Also, fruit with and without the disorder were assessed for contents of Ca, Mg, K, and N, as well as the K/Ca, Mg/Ca, and N/Ca ratios. Fruit stored at 1.0 kPa O₂ + 3.0 kPa CO₂ had higher incidence of flesh browning than those stored at 0.5 kPa O₂ + < 0.03 kPa CO₂ and 1.0 kPa O₂ + < 0.03 kPa CO₂, as well as higher severity of disorder than all the other storage conditions. Pears with flesh browning had lower Ca content, as well as higher K content and higher K/Ca, Mg/Ca, and N/Ca ratios than fruit without the disorder. However, the multivariate analysis of all these mineral elements showed that the K/Ca ratio provides the best discrimination between fruit with and without flesh browning in ‘Rocha’ pears.

Key words
Pyrus communis; canonical discriminant analysis; storage; calcium deficiency; physiological disorder