Influence of blanching and freezing broccoli (Brassica oleracea var. italica) prior to storage and cooking on glucosinolate concentrations and myrosinase activity

V. Rungapamestry, A.J. Duncan, Z. Fuller, B. Ratcliffe

Research output: Contribution to journalArticlepeer-review

Abstract

Glucosinolates contribute to the chemoprotective
eVects of Brassica vegetables. The inXuence of blanching
and freezing broccoli, followed by storage or cooking,
on its glucosinolate concentration and myrosinase activity
was investigated. Myrosinase activity was reduced by 93%,
while glucosinolate concentration was unaltered after
blanch-freezing broccoli. Blanch-frozen Brassica retained
the glucosinolate content of its fresh counterpart after storage
at T = ¡20 °C for up to 90 days. Fresh or blanch-frozen
broccoli was stir-fried, boiled, boiled and kept hot for 2 h, or left uncooked. Stir-frying retained the highest glucosinolate concentration and myrosinase activity, regardless of pre-cooking. Boiling and keeping blanch-frozen broccoli
hot completely denatured myrosinase and decreased glucosinolate concentration by 42%. Aromatic and indole glucosinolates were reduced to a larger extent than aliphatic glucosinolates, especially when boiled broccoli was kept hot. The Wnal concentration of glucosinolates in Brassica is inXuenced by cooking, while the myrosinase activity is modiWed by pre-treatment and subsequent cooking.
Original languageEnglish
Pages (from-to)37-44
Number of pages8
JournalEuropean Food Research and Technology
Volume227
Issue number1
DOIs
Publication statusPublished - 24 Jul 2007

Keywords

  • Glucosinolates
  • Myrosinase
  • Broccoli
  • Blanching
  • Freezing
  • Cooking
  • Storage

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