Development and control of scald on wonderful pomegranates during long-term storage

Scald of the husk surface is an important factor limiting long-term storage of pomegranates and little information is available about its ause and methods of control. We evaluated the efficacy of prestorage treatment with diphenylamine and/or 1-methylcyclopropene and of tmospheric modification during storage on scald incidence and severity on Wonderful pomegranates. Scald incidence and severity were greater on pomegranates harvested during late season than on those harvested during mid season, ndicating that this disorder may be associated with senescence. All pomegranates from both harvests that were kept in air exhibited some cald after 4–6 months at 7 ◦C. Neither diphenylamine, at 1100 or 2200 L L−1, nor 1-methylcyclopropene at 1 L L−1, alone or together educed scald incidence and severity. In contrast, the three controlled atmosphere (CA) storage conditions tested (1 kPa O2, 1 kPa O2 + 15 kPa O2 and 5 kPa O2 + 15 kPa CO2) significantly reduced scald incidence and severity on pomegranates from both harvest dates for up to 6 months t 7 ◦C. However, the two CA treatments with 1 kPa O2 resulted in greater accumulation of fermentative volatiles (acetaldehyde, ethanol, nd ethyl acetate) than the CA treatment with 5 kPa O2, especially in the mid-season-harvested pomegranates. In addition to its fungistatic ffects, 15 kPa CO2 appears to be critical for inhibition of scald development on pomegranates. These results confirm recommendation by ess-Pierce and Kader (2003) of 5 kPa O2 + 15 kPa CO2 (balance N2) as the optimal CA for pomegranates at 7 ◦C and 90–95% relative umidity. Since very little if any -farnesene or its conjugated trienol oxidation products were found in the peel of pomegranates, it appears hat the biochemical basis of scald in pomegranates is different from that in apples. CA storage (5 kPa O2 + 15 kPa CO2) decreased or prevented hanges in carotenoid, acyl lipid, and phenylpropanoid metabolism that were associated with scald development in stem-end peel tissue of ir-stored fruit and are indicative of stress and/or senescence. 2006 Elsevier B.V. All rights reserved.