Novel insights into ascorbate retention and degradation during the washing and post-harvest storage of spinach and other salad leaves

Rebecca Dewhirst, Graham J. J. Clarkson, Steve D. Rothwell, Stephen Fry

Research output: Contribution to journalArticlepeer-review

Abstract

Post-harvest treatments of pre-packaged salad leaves potentially cause l-ascorbate loss, but the mechanisms of ascorbate degradation remain incompletely understood, especially in planta. We explored the extent and pathways of ascorbate loss in variously washed and stored salad leaves. Ascorbate was assayed by 2,6-dichlorophenolindophenol titration, and pathways were monitored by 14C-radiolabelling followed by high-voltage electrophoresis. All leaves tested showed ascorbate loss during storage: lettuce showed the greatest percentage loss, wild rocket the least. Spinach leaves were particularly prone to losing ascorbate during washing, especially with simultaneous mechanical agitation; however, washing in the presence of hypochlorite did not significantly increase ascorbate loss. In spinach, [14C]oxalate was the major product of [14C]ascorbate degradation, suggesting that commercial washing causes oxidative stress. This study highlights that ascorbate/dehydroascorbic acid are lost via the oxidative pathway during washing and post-harvest storage of salad leaves. Thus changes to washing procedures could potentially increase the post-harvest retention of ascorbate.
Original languageEnglish
Pages (from-to)237–246
JournalFood Chemistry
Volume233
Early online date17 Apr 2017
DOIs
Publication statusPublished - 15 Oct 2017

Keywords

  • Vitamin C
  • Spinach
  • Salad leaves
  • Washing
  • Post-harvest storage
  • Chlorine
  • Oxalic acid

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