Il rooibos è una pianta originaria del Sud Africa, nota scientificamente come Aspalathus linearis. La sua infusione, spesso chiamata tè rooibos, è apprezzata per il sapore dolce e leggermente nocciolato.
Processo di produzione industriale
- Raccolta. Le foglie di Rooibos vengono raccolte manualmente nelle regioni montuose del Sudafrica, dove la pianta cresce naturalmente. La raccolta avviene tipicamente durante l'estate.
- Fermentazione. Dopo la raccolta, le foglie fresche di Rooibos vengono sottoposte a un processo di fermentazione naturale, che ne esalta il sapore e il colore. Successivamente, le foglie vengono essiccate al sole per arrestare il processo di fermentazione.
- Estrazione. Le foglie essiccate vengono poi macinate e sottoposte a un processo di estrazione per separare i composti bioattivi. L'estrazione può essere effettuata utilizzando acqua calda o solventi come etanolo, a seconda del tipo di estratto desiderato e del suo uso finale.
- Concentrazione. L'estratto liquido ottenuto viene concentrato sotto vuoto e purificato per rimuovere impurità e solventi residui, ottenendo così un estratto di Rooibos concentrato e di alta qualità.
- Controllo Qualità. L'estratto di Rooibos è sottoposto a controlli di qualità per verificare la concentrazione di antiossidanti, la purezza e l'assenza di contaminanti. Questi test possono includere analisi spettroscopiche, cromatografiche e microbiologiche.
Applicazioni commerciali:
Bevande. Il rooibos è conosciuto come base per infusi e tè, apprezzati per il loro gusto unico e l'assenza di caffeina, rendendoli adatti al consumo serale o come alternative al tè tradizionale per chi evita la caffeina.
Prodotti Cosmetici. Grazie alle sue proprietà antiossidanti, anti-infiammatorie (1) e antimicrobiche dovute alla presenza di polifenoli (2), il Aspalathus linearis trova applicazione in diversi prodotti cosmetici, inclusi creme per la pelle, lozioni e prodotti per la cura dei capelli, per aiutare a proteggere e rigenerare la pelle.
Integratori Alimentari. Il rooibos è utilizzato in integratori per i suoi effetti benefici sulla salute, come il supporto alla digestione, il miglioramento della salute cardiovascolare e l'azione antiossidante che contribuisce a combattere i danni dei radicali liberi. Oltre ai benefici interni, il rooibos è utilizzato in prodotti per il sollievo da disturbi come l'eczema, le allergie e le irritazioni cutanee, grazie alle sue proprietà lenitive.
Sicurezza
Rooibos è generalmente ritenuto sicuro, ma la sua efficacia dipende fortemente dalla lavorazione e dalla purezza delle materie prime (3), inoltre sono stati segnalati casi di tossicità epatica (4) per cui sarebbe buona norma non esagerare nell'assunzione.
In particolare è da segnalare che Aspalathus linearis è sensibile alla contaminazione ambientale e quindi si deve usare cautela nei pazienti che ricevono il trattamento con medicinali allopatici per evitare alterazioni indesiderate della concentrazione plasmatica del farmaco (5).
Bibliografia_____________________________________________________________________
(1) Baba, H., Ohtsuka, Y., Haruna, H., Lee, T., Nagata, S., Maeda, M., ... & Shimizu, T. (2009). Studies of anti‐inflammatory effects of Rooibos tea in rats. Pediatrics International, 51(5), 700-704.
Abstract. Background: Rooibos tea is known to be caffeine free with abundant flavonoids. Aspalathin and nothofagin, the main flavonoids contained in Rooibos tea, have stronger anti-oxidative activity than other flavonoids. As oxidative stress can induce inflammation, the anti-inflammatory effects of Rooibos tea were investigated using a rat colitis model. Conclusion: Rooibos tea may prevent DNA damage and inflammation by its anti-oxidative activity in vivo. As Rooibos tea is free from caffeine, routine intake may be safe and useful in reducing oxidative stress in children.
(2) Krafczyk, Nicole, and Marcus A. Glomb. Characterization of phenolic compounds in rooibos tea. Journal of Agricultural and Food Chemistry 56.9 (2008): 3368-3376.
Abstract. Polyphenols present in rooibos, a popular herbal tea from Aspalathus linearis, were isolated in two steps. First, phenolic ingredients were separated by multilayer countercurrent chromatography (MLCCC). Preparative high-performance liquid chromatography (HPLC) was then applied to obtain pure flavonoids. The purity and identity of isolated compounds was confirmed by different NMR experiments, HPLC-diode array detector (DAD), or gas chromatography−mass spectrometry (GC-MS) analysis. This strategy proved to be valid to isolate material in up to gram quantities and to verify known and previously not published polyphenol structures. In addition the chemistry of dihydrochalcones and related intermediates was studied. The dihydrochalcone aspalathin was oxidized to the corresponding flavanone-C-glycosides ((R)/(S)-eriodictyol-6-C-β-d-glucopyranoside and (R)/(S)-eriodictyol-8-C-β-d-glucopyranoside). Flavanone-6-C-β-d-glucopyranosides were further degraded to flavones isoorientin and orientin.
(3) Areo, O. M., & Njobeh, P. B. (2021). Risk assessment of heavy metals in rooibos (Aspalathus linearis) tea consumed in South Africa. Environmental Science and Pollution Research, 28(42), 59687-59695.
Abstract. A total of 80 rooibos tea samples from a range of brands were purchased from various registered retail shops in South Africa. The samples were bought during 2019 winter (40) and summer (40) period which are classified as 6 natural rooibos, 18 herbal rooibos samples, and 16 flavor rooibos samples and subjected for heavy metal analysis such as chromium (Cr), iron (Fe), arsenic (As), cadmium (Cd), and lead (Pb) using inductively coupled plasma mass spectrometer (ICP-MS). Human health risks were determined by estimating the daily intake non-cancer hazard quotient (THQ) and hazard index (HI) via oral exposure to toxic elements based on daily tea consumption. The concentration range of the determined heavy metals in rooibos tea samples were as follows: Cr (0.17–11.98 mg/kg), Fe (31–450 mg/kg), As (ND–0.51 mg/kg), Cd (0.09–0.17 mg/kg), and Pb (0.06–2.73 mg/kg). Cr was found in higher amount when compared to the World Health Organization (WHO) permissive limit (1.3 mg/kg). The concentrations of all studied heavy metals during winter and summer period were compared using two-way Anova, and no significant differences (p = 0.832) were observed for the two seasons. Both the target risk quotient (THQ) and the hazard index (HI) levels in all analyzed tea were well below 1, implying that intake of rooibos tea with analyzed heavy metals should not cause a threat to human health. On the other hand, the continuous intake due to the high concentrations of trace metals such as Cr may pose a serious chronic health risk due to accumulation in body tissues over time. The study, therefore, suggests constant monitoring of these heavy metals in teas in order to limit the risk of exceeding the permissive limits.
(4) Carrier P, Debette-Gratien M, Jacques J, Grau M, Loustaud-Ratti V. Rooibos, a fake friend. Clin Res Hepatol Gastroenterol. 2021 Mar;45(2):101499. doi: 10.1016/j.clinre.2020.06.020. Epub 2020 Aug 20. PMID: 32828746.
Abstract. Rooibos is consumed worldwide and its use considered safe. It contains scavengers of free radicals and is so is deemed to be a liver protector. Nevertheless, hepatic toxicity exists even if rare. It is probably underdiagnosed and clinicians should think about it in case of acute hepatitis. We report a case of liver injury attributed to Rooibos.
(5) Pyrzanowska J. The toxic contaminants of Aspalathus linearis plant material as well as herb-drug interactions may constitute the health risk factors in daily rooibos tea consumers. Int J Environ Health Res. 2023 Feb;33(2):129-142. doi: 10.1080/09603123.2021.2009780. Epub 2021 Nov 25. PMID: 34823434.
Abstract. Rooibos tea is brewed using Aspalathus linearis plant material sensitive to environmental contamination. This review covers the safety data from preclinical experiments as well as human studies and delivers a report on its hepatic activity. In vitro tea investigation reveals antioxidative and anti-mutagenic features and ability to modulate microsomal enzymes. In rodent research, it exerts protective or neutral impact on liver functions and morphology, yet several human case reports suggest possible acute hepatic damage. Summarizing rooibos consumption seems to be safe in terms of hepatotoxicity; however, there may be designated a group of consumers with higher risk of liver irritation. The contamination of plant material may contribute to herb-induced liver injury. Due to the impact on CYPs, there is a possible risk of herb-drug interactions affecting bioavailability of some co-administered medicines. Caution should be exercised in patients receiving the treatment with allopathic medicines to avoid untoward alteration of drug plasma concentration.
Aspalathus linearis 
