Effect of L-ascorbic acid, sugar, pectin and freeze-thaw treatment on polyphenol content of frozen strawberries
Jan Oszmiański , Aneta Wojdyło , Joanna Kolniak-Ostek
AbstractThe stability of phenolic compounds of three strawberry cultivars was evaluated for changes during prefreezing treatments, storage and various freezing and thawing conditions. Polyphenol content was determined by HPLC-DAD-FL The sum of assayed polyphenolic (proanthocyanidin and monomeric flavan-3-ols, anthocyanins, ellagic acid, p-cournaric acid) represented 2858.4 mg/kg in Kent, 2893.1 mg/kg in Elkat, and 2438.0 mg/kg in Senga Sengana. After freezing, 4.5-33.6% of polyphenols were lost; protective effects of prefreezing treatments were seen on anthocyanidins and proanthocyaniclins: ascorbic acid was the most effective pretreatment, allowing retention of 3.9-27.5% of anthocyanins, and almost total recovery (3.9-23.9 when associated with liquid nitrogen freezing. Pectin and sugar only allowed retention of 3.0-25.1% and 5.5-25.4% of the antocyanins, respectively. Thawing of the strawberries in a microwave oven (instead of 20 h at 20 degrees C) had a further positive effect on retention of anthocyanins, proanthocyanins, (+)-catechin and ellagic acid. (C) 2008 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.
|Journal series||LWT-Food Science and Technology, ISSN 0023-6438, (A 35 pkt)|
|Publication size in sheets||0.5|
|Keywords in English||Fragaria x ananassa Duch; Polyphenols; Anthocyanins; Proanthocyanidins; Ellagic acid; Freezing and thawing conditions; Microwave thawing|
|Publication indicators||= 52; = 61; : 2009 = 1.273; : 2009 = 2.114 (2) - 2009=2.259 (5)|
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