Development of browning induced in `Braeburn' apple (Malus ×domestica Borkh.) fruit by a damaging CO2 concentration was monitored weekly using magnetic resonance imaging (MRI) during a 4-week storage trial (0.5 °C, 2 kPa O2/7 kPa CO2). Discrete patches of high-intensity signal, distributed randomly throughout the fruit, were observed in multislice images of samples after 2 weeks of storage; these patches were eventually confirmed as being sites of browning reactions after dissection at the end of the trial. Subsequently (weeks 3 and 4), signal intensity at sites of incipient damage increased and patches enlarged and coalesced. After 2 weeks of storage, the extent of affected tissue, averaged across all image slices, was 1.5%, increasing to 15.9% and 21.3% after 3 and 4 weeks. The average rate at which tissue damage spread in individual slices was 0.81 (range: 0–3.70) cm2·d–1 between weeks 2 and 3, declining to 0.32 (range: 0–1.55) cm2·d–1 in the final week. Tissue damage induced under these conditions did not spread at the same rate at all locations within individual fruit, nor was it preferentially located toward the stem or calyx ends of the fruit.
Christopher J. Clark and Douglas M. Burmeister
H. John Elgar, Douglas M. Burmeister, and Christopher B. Watkins
`Braeburn' apple (Malus ×domestica Borkh.) fruit can be susceptible to the development of an internal disorder called “`Braeburn' browning disorder” (BBD). Factors associated with development of this disorder were investigated. Susceptibility to injury was greater in fruit exposed to 2 or 5 kPa CO2 than to 0 kPa CO2 during storage. Susceptibility also increased with decreasing O2 partial pressure in the range of 5 to 1 kPa in the storage atmosphere. However, fruit stored in 1 kPa O2 remained firmer than those stored at higher partial pressures, regardless of CO2 level. BBD appeared to develop during the first 2 weeks of storage, and delays in air at 0 °C prior to controlled-atmosphere (CA) storage decreased incidence and severity of the disorder. The incidence of BBD was also reduced when the time to establish CA conditions was prolonged. We recommend that `Braeburn' apples be stored under CA conditions of ≤1.0 kPa CO2 and 3.0 kPa O2. Delayed application of CA for 2 weeks after fruit enter the coldstorage may also reduce development of BBD.
H. John Elgar, Nagin Lallu, and Christopher B. Watkins
The incidence and severity of “`Braeburn' browning disorder” (BBD), a CO2-induced disorder of `Braeburn' apple (Malus ×domestica Borkh.), vary markedly with production district and orchard block. We investigated the effects of harvest date, blush, and crop load on fruit maturity, minerals, skin permeance, and BBD incidence. Incidence of BBD was higher in late-than in early-harvested fruit and in fruit on light than on heavily cropping trees, but blush intensity did not influence susceptibility to the disorder. Fruit maturity factors were affected by region, harvest date, blush type, and crop load, but no consistent relationships between these factors and BBD occurrence were found. Concentrations of Ca, Mg, and/or K were influenced by harvest date, blush type, and crop load, and skin permeance to gas exchange was affected by growing region and blush type, but not by harvest date or crop load. However, no physiological or mineral factor measured in this study was strongly correlated with susceptibility of fruit to BBD. Fruit from orchards that have a history of susceptibility to BBD, or subjected to adverse harvest date, regional, crop load, microclimate, and seasonal influences, should be segregated at harvest, and should not be held in controlled-atmosphere (CA) storage. Crop load should be managed to reduce the occurrence of biennial bearing.
Yiping Gong, Peter M.A. Toivonen, O.L. Lau, and Paul A. Wiersma
Apple fruits (Malus domestica Borkh. cv. Braeburn) harvested from two orchards (A and B) on the same day were stored in air or pretreated in air for 0, 2 (2dCA) or 4 weeks (4dCA) before moving into controlled atmosphere (CA) storage with 1.5% O2 + 5% CO2. During storage at 1 °C for 9 weeks in air and/or CA, changes of pyruvate decarboxylase (PDC) activity, alcohol dehydrogenase (ADH) activity, acetaldehyde (AA) and ethanol (EtOH) concentrations in flesh tissue were assayed in addition to the incidence of Braeburn browning disorder (BBD). Immediate introduction to CA conditions induced the development of BBD with the highest incidence 62.2%, however delaying application of CA for 2 and 4 weeks reduced the incidence of BBD to 38.5% and 27.0%. The development of disorder in grower B was less than in grower A. 2dCA and 4dCA treatments did not influence PDC activity compared with treatment of CA. However, ADH activity and the accumulation of AA and EtOH in treatments of 2dCA and 4dCA were markedly lower than those in CA. The accumulation of AA in grower B was lower than grower A. The results of this study suggest that the delayed application of CA reduced BBD and this may be due to reduced anaerobic metabolism of fruits in the delayed CA.
Elena de Castro, William V. Biasi, and Elizabeth J. Mitcham
internal flesh browning in ‘Fuji’ apples ( Volz et al., 1998 ) and ‘Braeburn’ browning disorder ( Elgar et al., 1998 ). Table 1. Incidence of flesh browning in 2002 and 2004 after 2 months of storage in air or indicated controlled atmosphere at 0
Elena de Castro, Bill Biasi, Elizabeth Mitcham, Stuart Tustin, David Tanner, and Jennifer Jobling
al., 1998 ) and Braeburn browning disorder (BBD) ( Elgar et al., 1998 ; Lau, 1998 ). Flesh browning in apples occurs intermittently and in unpredictable patterns, perhaps due to the interaction of yet-to-be-identified pre- and postharvest factors
Carolina Contreras, Nihad Alsmairat, and Randy Beaudry
also found in ‘Braeburn’ apples and is known as “Braeburn browning disorder” (BBD) per Elgar et al. (1998) . BBD is triggered by elevated CO 2 and reduced O 2 during CA storage; hence, the recommendations are to store ‘Braeburn’ apples at less than 1