Articles
Rooibos reimagined: green extraction and resin-based purification of phenolics for postharvest preservation
Article number
1466_62
Pages
511 – 518
Language
English
Abstract
Postharvest losses account for about 30% of global food production, threatening food security and sustainability.
Natural solutions are vital for efficient, consumer-friendly postharvest management.
Among these, antioxidants such as flavonoids, including aspalathin, nothofagin, quercetin, and isoorientin, can reduce oxidative stress and delay crop senescence.
Rooibos tea (Aspalathus linearis), valued for its antioxidant and health benefits, is increasingly used in pharmaceutical, cosmetic, and nutraceutical products.
However, poor extraction methods limit the full use of rooibos by-products.
Natural deep eutectic solvents (NADES) offer a greener, more efficient alternative for recovering bioactive flavonoids from rooibos leaf spent (RLS). In the present study, NADES, composed of choline chloride as the hydrogen bond acceptor, combined with lactic acid (CLac), citric acid (CCit), glucose (CGluc), or sucrose (CSuc), were used to extract phenolic compounds from rooibos leaf spent, with 60% (v/v) ethanol used as a conventional solvent for comparison.
The phenolic profiles of the extracts were subsequently investigated using liquid chromatography-mass spectrometry (LC-MS). A total of 28 compounds, including 8 polyphenols and 20 flavonoids, were identified.
CCit extract exhibited the highest concentrations of major flavonoids in rooibos, including orientin (23.5 mg L‑1), aspalathin (18.3 mg L‑1), quercetin (18.3 mg L‑1), and vitexin (7.9 mg L‑1). For the first time, this study detected the existence of fisetin (16.5-36.4 mg L‑1) in RLS, a senolytic agent that selectively targets and eliminates senescent cells.
These results highlight the efficacy of NADES, specifically CCit, in enhancing the valorisation of RLS by extracting high concentrations of major flavonoids, including fisetin with senolytic properties.
This approach upcycles agricultural waste into functional, eco-friendly coatings that aid food preservation and reduce waste, while delivering higher yields of bioactive compounds, lowering production costs, and supporting the transition toward sustainable, circular bioeconomy models in the rooibos industry and beyond.
Natural solutions are vital for efficient, consumer-friendly postharvest management.
Among these, antioxidants such as flavonoids, including aspalathin, nothofagin, quercetin, and isoorientin, can reduce oxidative stress and delay crop senescence.
Rooibos tea (Aspalathus linearis), valued for its antioxidant and health benefits, is increasingly used in pharmaceutical, cosmetic, and nutraceutical products.
However, poor extraction methods limit the full use of rooibos by-products.
Natural deep eutectic solvents (NADES) offer a greener, more efficient alternative for recovering bioactive flavonoids from rooibos leaf spent (RLS). In the present study, NADES, composed of choline chloride as the hydrogen bond acceptor, combined with lactic acid (CLac), citric acid (CCit), glucose (CGluc), or sucrose (CSuc), were used to extract phenolic compounds from rooibos leaf spent, with 60% (v/v) ethanol used as a conventional solvent for comparison.
The phenolic profiles of the extracts were subsequently investigated using liquid chromatography-mass spectrometry (LC-MS). A total of 28 compounds, including 8 polyphenols and 20 flavonoids, were identified.
CCit extract exhibited the highest concentrations of major flavonoids in rooibos, including orientin (23.5 mg L‑1), aspalathin (18.3 mg L‑1), quercetin (18.3 mg L‑1), and vitexin (7.9 mg L‑1). For the first time, this study detected the existence of fisetin (16.5-36.4 mg L‑1) in RLS, a senolytic agent that selectively targets and eliminates senescent cells.
These results highlight the efficacy of NADES, specifically CCit, in enhancing the valorisation of RLS by extracting high concentrations of major flavonoids, including fisetin with senolytic properties.
This approach upcycles agricultural waste into functional, eco-friendly coatings that aid food preservation and reduce waste, while delivering higher yields of bioactive compounds, lowering production costs, and supporting the transition toward sustainable, circular bioeconomy models in the rooibos industry and beyond.
Publication
Authors
Z.P. Mina, K.A. Jimoh, T.M. Pfukwa, O.A. Fawole
Keywords
Rooibos leaf spent, phenolic compounds, NADES, postharvest preservation, circular economy
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