Aiming for the perfect cup of rooibos and honeybush – Challenges and strategies in balancing “taste” and health

Rooibos (Aspalathus linearis) and honeybush (Cyclopia species) are indigenous South African fynbos plants traditionally used as medicinal herbal teas. Today, they are enjoyed for their unique “taste” (a term commonly used by consumers when referring to flavour) and are recognised as “healthy” beverages. The health benefits of these teas are largely attributed to their high phenolic content, particularly aspalathin in rooibos and mangiferin in honeybush, which are the main polyphenols produced by the respective plants. Although the green variants of rooibos and honeybush contain higher levels of aspalathin and mangiferin, their flavourful oxidised counterparts, red rooibos and brown honeybush, are generally preferred by consumers. Processing, particularly the essential oxidation step in the production of both red rooibos and brown honeybush, significantly impacts the sensory profiles and polyphenol levels of a cup of tea. Storage of their green teas can also lead to the loss of aspalathin and mangiferin. The main focus of this review is thus a discussion of the trade-offs between maximising desirable sensory properties and retaining high levels of bioactive phenolics in rooibos and honeybush. Challenges in limiting polyphenol oxidation during processing and storage, and the strategies employed, including plant breeding and harvesting for optimal quality and bioactive content, are highlighted. The review also examines the impact of other ingredients in beverage products. A short section focusses on the nanoencapsulation and complexation of rooibos and honeybush extracts. The need for detailed descriptions of the specific herbal tea (species; oxidation status) and sample preparation methods used in health-related studies to enable comparison of results across studies are highlighted. The review concludes with suggestions for future research to help the South African herbal tea industry meet consumer demands for teas that not only “taste” good but also provide health and wellness benefits.