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Use of Green Rooibos ( Aspalathus linearis ) Extract and Water-Soluble Nanomicelles of Green Rooibos Extract Encapsulated with Ascorbic Acid for Enhanced Aspalathin Content in Ready-to-Drink Iced Teas.
MedLine Citation:
PMID:  20923193     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Heat-induced changes in aspalathin, iso-orientin, and orientin content of ready-to-drink (RTD) green rooibos iced tea formulations were investigated. An organic-solvent-based aspalathin-enriched extract prepared from green rooibos was used "as-is" or encapsulated with ascorbic acid in a water-soluble nanomicelle-based carrier system. The common iced tea ingredients, ascorbic acid, and/or citric acid were added to the iced tea containing green rooibos extract. Only citric acid was added to the iced tea containing the nanomicelles. Heat treatments consisted of pasteurization (93 °C/5 min and 93 °C/30 min), normal-temperature sterilization (NTS; 121 °C/15 min), and high-temperature sterilization (HTS; 135 °C/4 min). Pasteurization had little or no effect on the flavonoid content. NTS and HTS induced significant losses in the flavonoids. The addition of citric and ascorbic acids improved the stability of the flavonoids, but encapsulation of green rooibos extract with ascorbic acid in nanomicelles did not offer additional stability. The only benefit of using the water-soluble nanomicelles was the improved clarity of the RTD product. Iso-orientin and orientin contents were substantially less affected than aspalathin by the heat treatments, partially because of conversion of aspalathin to these flavones, which countered losses. 5-Hydroxymethylfurfural (HMF), a known dehydration product of hexoses under mild acidic conditions and also a degradation product of ascorbic acid, was observed in formulations containing citric and/or ascorbic acids.
Authors:
Elizabeth Joubert; Melvi Viljoen; Dalene De Beer; Christiaan J Malherbe; D Jacobus Brand; Marena Manley
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2010-10-5
Journal Detail:
Title:  Journal of agricultural and food chemistry     Volume:  -     ISSN:  1520-5118     ISO Abbreviation:  -     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-10-6     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0374755     Medline TA:  J Agric Food Chem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Agricultural Research Council (ARC) Infruitec-Nietvoorbij, Private Bag X5026, Stellenbosch 7599, South Africa.
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