Sensory characterization of rooibos tea and the development of a rooibos sensory wheel and lexicon

Rooibos samples were collected throughout the 2009 harvesting season from different geographic areas in the Western Cape, South Africa, and from different producers to capture as much potential variation in rooibos sensory characteristics as possible. The quality (i.e. the appearance of the leaves, and the color and flavor of the infusion) of 69 samples was evaluated by expert graders, and samples were grouped into four quality grades. Using descriptive analysis sensory profiles of the rooibos samples were developed and 121 aroma, flavor, taste, and mouthfeel descriptors were generated. A rooibos sensory wheel was created by selecting 27 flavor, taste and mouthfeel attributes and grouping these terms together to form a logical, convenient and user-friendly overview of the sensory descriptors associated with rooibos. The most frequently occurring descriptors were selected to compile a rooibos sensory lexicon of 14 flavor, taste and mouthfeel attributes along with a definition and reference standard for each term. It was found that the term “characteristic” rooibos flavor may be described as a combination of honey, woody and herbal-floral notes with a slightly sweet taste and subtle astringency. Also, differences in the sensory characteristics between and within different quality grades were established with low-quality tea often being associated with green, hay-like and musty flavors and a bitter or sour taste. High-quality tea was generally associated with pleasant rooibos attributes including honey, woody, floral and caramel notes and a sweet taste. This research is a first step towards the broader objective of standardizing the sensory terminology of rooibos tea.

► Sensory profiles for rooibos tea samples of four quality grades were developed. ► Sensory descriptors were summarised in a rooibos sensory wheel and lexicon. ► Large variation in sensory attributes was observed between rooibos samples. ► Characteristic attributes are honey, woody, floral, sweet taste and astringency.