Effect of low-oxygen atmospheres on quality and superficial scald of Topred apples

Resumen

In a 2-year study, Topred (TR) apples harvested from the area of Lleida (NE Spain) were treated with 3 rates (0, 1000 and 2000 ppm) of diphenylamine (DPA) and held in 3 different experimental storage conditions: standard controlled atmosphere (CA) with 3% O2 and 3% CO2; low oxygen (LO) atmosphere with 2% O2 and 2% CO2; ultra-low oxygen (ULO) atmosphere with 1% O2 and 1% CO2. All samples were maintained at 1 °C and 93-94% relative humidity. The incidence of super ficial scald and quality parameters were assessed in February, April and June, after storage plus 1 and 7 days at 20 °C, in samples from each treatment (anti-scald rate and storage atmosphere). Storage in ULO was effective in extending the storage life of the fruit. Firmness retention was better in these fruits than in fruits held in CA and LO storage; generally, after a 7-day post-storage holding period at 20 °C, the differences were maintained. The soluble solids content and titratable acidity were similar for all treatments. These changes were similar for the 2 years studied. Over one season (1993-94) the ULO atmosphere provided the best control of superficial scald in TR apples, although a low concentration of anti-scald was necessary in some cases. During the 7-day post-storage holding period the fruit of all treatments showed an increased incidence of scald, but fruit from the ULO treatment could be considered acceptable for market distribution. Susceptibility of fruit to scald exhib ited seasonal variation; in the 1994-95 season, DPA treatment was necessary to control scald in ULO apples. No appreciable increase in low O2 injury was found in this cultivar held in 1 or 2% O2.