Natural Variation in the Phenolic Composition of Rooibos and Changes During Production of Herbal Tea and Other Products

Development of sensory tools for green rooibos (Aspalathus linearis (Burm.f.) R.Dahlgren) and changes in quality attributes during shelf‐life storage

“…According to the UN Food and Agriculture Organization, such a moisture content would give an adequate safety margin to prevent microbial growth in black tea during storage, but a moisture content ≥6 g (100 g) −1 db causes product quality deterioration 36 . No data are available for green rooibos, but samples of green rooibos with a moisture content ≤3 g (100 g) −1 db, stored in sealed containers, were shown to retain their color 32 . The moisture content of the green rooibos samples for the present study varied from 1.31 to 7.39 g (100 g) −1 db (mean = 4.50 g (100 g) −1 db) (Table 1).…”

“…36 No data are available for green rooibos, but samples of green rooibos with a moisture content ≤3 g (100 g) −1 db, stored in sealed containers, were shown to retain their color. 32 The moisture content of the green rooibos samples for the present study varied from 1.31 to 7.39 g (100 g) −1 db (mean-= 4.50 g (100 g) −1 db) (Table 1). Samples from the 2022 production year which were stored for less than 1 month before sampling and analysis had the lowest moisture content (<4 g (100 g) −1 db) (Fig.…”

“…Generally, the soluble solids concentration of green rooibos infusions is higher than that of fermented rooibos infusions (0.8–1.7 g L −1 ) 41 . This is to be expected since the fermentation process of rooibos decreases the soluble matter of the leaves 32 . Turbidity values of the green rooibos infusions varied between 30.9 and 134 NTU (mean = 72.9 NTU).…”

“…This is not unexpected since the processing of green rooibos does not involve keeping the plant material moist for an extended period as required for the production of fermented rooibos. 32 The attributes 'dusty', 'seaweed' and 'planky/pencil shavings', previously considered to be undesirable in fermented rooibos, 31 were perceived at very low intensities (<5) in some infusions (Fig. 1).…”

“…41 This is to be expected since the fermentation process of rooibos decreases the soluble matter of the leaves. 32 Turbidity values of the green rooibos infusions varied between 30.9 and 134 NTU (mean = 72.9 NTU). No data are available linking NTU values of rooibos to quality; however, rooibos infusions should be 'clear'.…”