Enhancing aspalathin stability in rooibos (Aspalathus linearis) ready-to-drink iced teas during storage: The role of nano-emulsification and beverage ingredients, citric and ascorbic acids

Date
2011-10-13
Authors
De Beer D.
Joubert E.
Viljoen M.
Manley M.
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Background: The effects of citric and ascorbic acids on the stability of aspalathin in rooibos (Aspalathus linearis) ready-to-drink (RTD) formulations containing fermented rooibos extract (FR), aspalathin-enriched green rooibos extract (GR) and aspalathin-enriched green rooibos extract ascorbic acid solubilisate (GR-solubilisate) were investigated during storage (12 weeks at 25 °C). Results: Storage of iced tea formulations containing FR and GR extracts reduced their flavonoid content. The aspalathin content of FR iced tea without citric or ascorbic acid was reduced to undetectable levels by week 8 of storage. Addition of citric acid resulted in improved stability of aspalathin, but ascorbic acid did not impart additional stability. Iso-orientin and orientin were less affected than aspalathin, presumably owing to partial conversion of aspalathin to these flavones. Similar results were obtained for GR iced tea formulations. Improved stability of aspalathin was noted in iced tea containing GR-solubilisate with or without citric acid. Lower pH was shown to favour stability, especially for fermented rooibos iced teas. Conclusion: Citric and ascorbic acids contribute to the stability of rooibos flavonoids during storage. Differences in stability between formulations are not due to pH differences but may be related to the matrix. © 2011 Society of Chemical Industry.
Description
Keywords
Aspalathus linearis, Flavonoids, Iced tea, PH, Rooibos, Storage
Citation
Journal of the Science of Food and Agriculture
http://www.scopus.com/inward/record.url?eid=2-s2.0-79960486034&partnerID=40&md5=6c33c0e65e6ca61478f90b0ce3c7ad60
URI
http://hdl.handle.net/10019.1/16823
Collections
Stellenbosch University - Scopus Publications