Resumen de Rooibos agro-processing waste as herbal tea products: optimisation of soluble solids extraction from dust and application to improve sensory profile, colour and flavonoid content of stem infusions
Manzimase Sishi, Magdalena Muller, Dalene De Beer, Marieta van der Rijst, Elizabeth Joubert
Rooibos represents 10% of the global herbal tea market. Shrinking production areas as a result of climate change necessitate the maximum conversion of plant biomass to product. The present study aimed to determine the potential of rooibos tea processing waste (i.e. fine dust and coarse stems) as potential flavour and herbal tea ingredients, respectively. RESULTS Hot water extraction of soluble solids (SS) from rooibos dust was optimised and extracts from different production batches (n?=?20) were prepared. Their sensory profiles were similar, although less intense than that of infusions of commercial rooibos (n?=?20) when diluted to the same SS content. The turbidity and flavonoid content of the diluted extracts was mostly lower (P??0.05). CONCLUSION Rooibos dust could be used to produce a rooibos flavour extract, whereas the prominent atypical, negative ?planky/pencil shavings? aroma note of the stems would limit their inclusion in commercial rooibos blends. ? 2019 Society of Chemical Industry
