Escurecimento da polpa em pera ‘Rocha’ influenciado pela composição mineral do fruto e condições de atmosfera controlada

Abstract

Resumo: O objetivo deste trabalho foi avaliar o efeito de condições de armazenamento em atmosfera controlada (AC) e da composição mineral do fruto sobre ocorrência de escurecimento da polpa em pera 'Rocha'. Os frutos foram armazenados sob diferentes condições de AC: 0,5 kPa O 2 + < 0,03 kPa CO 2 ; 1,0 kPa O 2 + < 0,03 kPa CO 2 ; 1,0 kPa O 2 + 1,0 kPa CO 2 ; 1,0 kPa O 2 + 2,0 kPa CO 2 e 1,0 kPa O 2 + 3,0 kPa CO 2 . Os frutos foram avaliados quanto à incidência e severidade de escurecimento da polpa após 9 meses de armazenamento (−0,5 ± 0,1 °C e UR de 96 ± 2%). Posteriormente, frutos com e sem a presença do distúrbio foram avaliados quanto às concentrações de Ca, Mg, K, N e as relações K/Ca, Mg/Ca e N/Ca. O armazenamento sob 1,0 kPa O 2 + 3,0 kPa CO 2 proporcionou aos frutos maior incidência de escurecimento da polpa em relação aos armazenados sob 0,5 kPa O 2 + < 0,03 kPa CO 2 e 1,0 kPa O 2 + < 0,03 kPa CO 2 , ocasionando ainda maior severidade do distúrbio em comparação às demais condições de armazenamento. Peras com escurecimento da polpa apresentaram menores concentrações de Ca, bem como concentrações mais elevadas de K e maiores relações dos elementos K/Ca, Mg/Ca e N/Ca, comparativamente a frutos sem incidência do dano. Todavia, a análise multivariada de todos esses elementos minerais mostrou que a relação K/Ca foi a mais indicada para discriminar frutos sem e com escurecimento da polpa em peras 'Rocha'. 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 O 2 + < 0.03 kPa CO 2 ; 1.0 kPa O 2 + < 0.03 kPa CO 2 ; 1.0 kPa O 2 + 1.0 kPa CO 2 ; 1.0 kPa O 2 + 2.0 kPa CO 2 and 1.0 kPa O 2 + 3.0 kPa CO 2 . 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 O 2 + 3.0 kPa CO 2 had higher incidence of flesh browning than those stored at 0.5 kPa O 2 + < 0.03 kPa CO 2 and 1.0 kPa O 2 + < 0.03 kPa CO 2 , 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. Palavras

The influence of the summer pruning on ‘Fuji’ apples storage under controlled atmosphere

“…A high N/Ca ratio can be harmful to fruit quality, as it increases the susceptibility to the occurrence of disorders related to Ca deficiency (Stüpp, Rosa, Amarante, Mafra, & Steffens, 2013). In the plant, N can be remobilized from leaves to fruit through the phloem (Miqueloto, Amarante, Steffens, Santos, & Mitcham, 2014;De Martin et al, 2017). The removal of shoots in the pruning carried out in February may have led to lower N transport to the fruit, which possibly caused the lower N concentration and N/Ca ratio in the fruit.…”

“…One of the factors that may explain the result is the lower N/Ca ratio found in fruit from plants pruned in February (Table 3). De Martin et al (2017) concluded that flesh browning in 'Rocha' pears is associated with lower Ca concentration, higher K concentration, and higher N/Ca, Mg/Ca, and K/Ca ratios. A lower N/Ca ratio can lead to a lower occurrence of flesh browning because Ca plays a fundamental role in maintaining the structure of the cell wall of fruit (Gao, Xiong, Li, Chen, & Zhu, 2019) and preserving the integrity of cell membranes (Miqueloto et al, 2014).…”

“…The concentrations of mineral elements (skin+flesh) (expressed in mg kg −1 FW), which make it the same for all parameters, were quantified using the methodology described by De Martin et al (2017). The N was determined using 0.2 g of the fresh sample digested with 2.0 mL of concentrated sulfuric acid (Merck, Germany) and 3.0 mL of hydrogen peroxide and kept at 350°C.…”