## 3 Results and Discussions
### Colour (L*, a*, b*, and C*) of Green Rooibos Extracts as a Function of Water Activity  
The colour of GRE and \(\beta\)-GRE fluctuated during the three weeks of storage at an \(\mathrm{a_{w}}\) of 0.11 to 0.4, followed by a drastic decrease at 0.75 (Table 3). An 80% decrease in the L* value was reported for GRE, while 45% was observed for \(\beta\)-GRE when comparing the initial colour and the day 21 \(\mathrm{a_{w}}\) of 0.75 \(\mathrm{a_{w}}\) (Figure 3). Similarly, the chroma (C*) of GRE decreased by 77%, whilst that of \(\beta\)-GRE remained almost constant at a 6% reduction, denoting stability imparted by encapsulation (Table 3). [PERSON] et al. [16] also reported higher L* values of \(\beta\)-CD-assisted extracts of olive pomace compared with aqueous extracts. Moreover, they also reported the effect of varying \(\mathrm{a_{w}}\) on the colour of extracts. They found that the darkening of aqueous extracts was increased as the \(\mathrm{a_{w}}\) increased and that \(\beta\)-CD-assisted extracts maintained the lightness regardless of changes in \(\mathrm{a_{w}}\). This further proves the impact of \(\beta\)-CD encapsulation on plant extract colour stability during storage. Plant extracts are known to impart natural pigments into the food they are added to. The colour of plant extracts is important as it determines the suitability of their use as a food additive [12]. The colour of green rooibos extract is important, particularly for its intended use in another part of this study. The main aim was to apply \(\beta\)-GRE to inhibit browning in canned apples. The deep red colour of the extract may have an effect that contributes to visual browning; therefore, the lighter the colour of the extract with increased antioxidant activity, the better. Moreover, at high temperatures applied in processing, in this case, canning, GRE polyphenols might oxidise, resulting in browning [8; 21]. Therefore \(\beta\)-CD encapsulated extracts are protected from direct exposure to heat. It is worth reiterating that in the studies by [2] and [16], \(\beta\)-CD-encapsulated extracts exhibited the highest antioxidant activity (AA) compared with their aqueous counterpart. The lighter colour, as well as increased AA, renders them suitable for application in inhibiting browning in canned apples.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Sample** & **RH** & **L*** & **C*** \\ \hline GRE & 0.11 & 45.57 \(\pm\) 0.20 \({}^{\mathrm{d}}\) & 29.75 \(\pm\) 0.53 \({}^{\mathrm{f}}\) \\ \hline GRE & 0.22 & 32.69 \(\pm\) 3.02 \({}^{\mathrm{c}}\) & 17.64 \(\pm\)1.53 \({}^{\mathrm{b}}\) \\ \hline GRE & 0.30 & 44.80 \(\pm\) 0.35 \({}^{\mathrm{d}}\) & 28.03 \(\pm\) 0.43 \({}^{\mathrm{e}}\) \\ \hline GRE & 0.40 & 47.79 \(\pm\) 0.11 \({}^{\mathrm{e}}\) & 23.23 \(\pm\) 0.25 \({}^{\mathrm{c}}\) \\ \hline GRE & 0.75 & 07.17 \(\pm\) 0.35 \({}^{\mathrm{a}}\) & 06.91 \(\pm\) 0.56 \({}^{\mathrm{a}}\) \\ \hline \(\beta\)-GRE & 0.11 & 53.08 \(\pm\) 0.43 \({}^{\mathrm{f}}\) & 28.03 \(\pm\) 0.57 \({}^{\mathrm{e}}\) \\ \hline \(\beta\)-GRE & 0.22 & 54.27 \(\pm\) 0.48 \({}^{\mathrm{f}}\) & 30.22 \(\pm\) 0.16 \({}^{\mathrm{f}}\) \\ \hline \(\beta\)-GRE & 0.30 & 48.52 \(\pm\) 0.36 \({}^{\mathrm{e}}\) & 30.55 \(\pm\) 0.33 \({}^{\mathrm{f}}\) \\ \hline \(\beta\)-GRE & 0.40 & 52.82 \(\pm\) 0.63 \({}^{\mathrm{f}}\) & 31.80 \(\pm\) 0.46 \({}^{\mathrm{g}}\) \\ \hline \(\beta\)-GRE & 0.75 & 28.39 \(\pm\) 0.83 \({}^{\mathrm{b}}\) & 26.37 \(\pm\) 0.86 \({}^{\mathrm{d}}\) \\ \hline \end{tabular} Data presented as mean \(\pm\) standard deviation (\(n=3\)) of \(\mathrm{a_{w}}\)—water activity, MC—moisture content, L*—lightness (0–100) and C*—chroma of GRE—green rooibos extract and \(\beta\)-GRE—betacyclodextrin-encapsulated green rooibos extract. ANOVA and Duncan’s Post Hoc test. *–8 Means with different letter superscripts in the same column denote significant differences (\(p<0.05\)).  
\end{table}
Table 3: The effect of relative humidity on the colour of aqueous and betacyclodextrin-encapsulated green rooibos extracts.