The TAC, total polyphenol, flavonol and flavanol contents of the commercially flavoured rooibos samples and their respective antioxidant characteristics are presented in Table 4.16. Significant (p < 0.05) differences were found within each of the antioxidant parameters measured. The FRAP of the camomile flavoured rooibos (traditional / fermented) (1 311 ± 185 µmol/L) and the berry flavoured iced tea (RTD) (724 ± 325 µmol/L) was the lowest of all the samples with the FRAP of these two samples also significantly (p < 0.05) lower than that of each of the other commercially flavoured rooibos samples respectively. The FRAP of the honey flavoured rooibos (traditional / fermented) (1 971.99 ± 425.66 µmol/L), the lemon flavoured iced tea (RTD) (3 008 ± 2 537 µmol/L) and the peach flavoured iced tea (RTD) (2 001 ± 1 459 µmol/L) were each also significantly (p < 0.05) lower than that of the lemon flavoured rooibos (traditional / fermented) (3 632 ± 1424 µmol/L), the lemon flavoured iced tea (powder) (2 734 ± 269 µmol/L), the instant apple fruit iced tea (powder) (4 750 ± 79 µmol/L) and the instant fruit punch and lemon flavoured iced tea (powder) (3 255 ± 314 µmol) respectively (see Table 4.16).
Table 4.16: Antioxidant characteristics of the commercially flavoured rooibos products
a FRAP: Ferric reducing antioxidant power assay presented as micromole (µmol) per litre (L).
b TEAC: Trolox equivalent antioxidant capacity assay presented as micromole (µmol) per litre (L).
c Total polyphenols, flavonol content and flavanol content presented as milligram (mg) per litre (L).
d Samples with different flavourings prepared as rooibos bags with freshly boiled water, stirring for 30 seconds and steeping for three minutes (checked against a laboratory timer).
e Values: Mean ± standard deviation.
f Flavanol content not detected (ND) in all samples providing for a negligible mean excluded in the data analysis.
g Commercially flavoured samples in powder form were prepared according to the instructions on the container.
h Ready-to-drink (RTD) samples were sampled directly from the container.
i Overall significant (p<0.05) difference in the Kruskal-Wallis Test one-way analysis of variance by ranks of the samples with the significant (p<0.05) contrasts transpiring on the post-hoc pairwise multiple comparisons indicated as a combined flavouring (number presented in brackets [e.g. camomile, (traditional / fermented) as 1] significantly different (-) to another commercially flavoured sample with each flavour presented as a number in brackets [e.g.honey (traditional / fermented) as 2]).
Flavour
The TEAC of the commercially flavoured rooibos samples was the highest for the lemon flavoured rooibos (traditional / fermented) and the peach flavoured iced tea (powder). The TEAC of the lemon flavoured rooibos (traditional / fermented) (1 741 ± 864 µmol/L) was significantly (p
< 0.05) higher than that of the lemon flavoured iced tea (powder) (1 113 ± 91 µmol/L), the instant apple fruit flavoured iced tea (powder) (987.9 ± 95.8 µmol), the instant fruit punch flavoured iced tea (powder) (1 200 ± 86 µmol/L), the instant fruit punch and lemon flavoured iced tea (powder) (843.9 ± 63.8 µmol/L) and the berry flavoured iced tea (RTD) (1 498 ± 76 µmol/L) respectively.
The TEAC of the peach flavoured iced tea (powder) (1 655 ± 154 µmol/L) in contrast was significantly (p < 0.05) higher than that of each of the other commercially flavoured rooibos samples respectively, besides for that of the berry flavoured iced tea (RTD) (1 498 ± 76 µmol/L) (see Table 4.16).
The TEAC of the commercially flavoured rooibos samples was the lowest for the instant apple flavoured fruit iced tea (powder) and the instant fruit punch and lemon flavoured iced tea (powder). The TEAC of the instant apple flavoured fruit iced tea (powder) (987.9 ± 95.8 µmol/L) (see Table 4.16) was significantly (p < 0.05) lower than that of camomile flavoured rooibos (traditional / fermented) (1 299 ± 108 µmol/L), the berry flavoured iced tea (RTD) (1 498 ± 76 µmol/L), the lemon flavoured iced tea (RTD) (1 347 ± 112 µmol/L) and the peach flavoured iced tea (RTD) (1 378 ± 120 µmol/L) in addition to the two commercially flavoured rooibos samples having the highest TEAC. The TEAC of the instant fruit punch and lemon flavoured iced tea (powder) (843.9 ± 63.8 µmol/L) (see Table 4.16) was significantly (p < 0.05) lower than that of the honey flavoured rooibos (traditional / fermented) (1 247 ± 104 µmol/L) in addition to the two commercially flavoured rooibos samples having the highest TEAC, the camomile flavoured rooibos (traditional / fermented) (1 299 ± 108 µmol/L) and all the three RTD flavoured iced tea samples (results elaborated below).
The TEAC of the camomile flavoured rooibos (traditional / fermented) (1 299 ± 108 µmol/L) and the lemon flavoured iced tea (RTD) (1 347 ± 112 µmol/L) were both significantly (p < 0.05) higher than that of the lemon flavoured iced tea (powder) (1 113 ± 91 µmol/L) and the instant fruit punch and lemon flavoured iced tea (powder) (843.9 ± 63.8 µmol/L) respectively and significantly (p <0.05) lower than that of the berry flavoured iced tea (RTD) (1 498 ± 76 µmol/L).
In addition, the TEAC of both the berry flavoured iced tea (RTD) (1 498 ± 76 µmol/L) and the peach flavoured iced tea (RTD) (1 378 ± 120 µmol/L) was significantly (p <0.05) higher than that of the honey flavoured rooibos (traditional / fermented) (1 247 ± 104 µmol/L), the lemon flavoured iced tea (powder) (1 113 ± 91 µmol/L), the instant fruit punch flavoured iced tea
(powder) (1 200 ± 86 µmol/L) and the instant fruit punch and lemon flavoured iced tea (powder) (843.9 ± 63.8 µmol/L), respectively. The TEAC of the berry flavoured iced tea (RTD) (1 498 ± 76 µmol/L) was in addition significantly (p < 0.05) higher than that of the lemon flavoured iced tea (RTD) (1 347 ± 112 µmol/L) and the peach flavoured iced tea (RTD) (1 378 ± 120 µmol/L) (see Table 4.16).
The total polyphenol content of the commercially flavoured rooibos samples was the highest for the instant apple fruit flavoured iced tea (powder) (629.2 ± 47.0 mg/L), the lemon flavoured rooibos (traditional / fermented) (626.7 ± 293.0 mg/L) and the instant fruit punch and lemon flavoured iced tea (powder) (625.4 ± 39.3 mg/L) and lowest for the berry flavoured iced tea (RTD) (41.92 ± 79.37 mg/L). The total polyphenol content of the instant apple fruit flavoured iced tea (powder) and the lemon flavoured rooibos (traditional / fermented) was significantly (p <
0.05) higher than that of the berry flavoured iced tea (RTD) and in addition to that of the camomile flavoured rooibos (traditional / fermented) (176.5 ± 46.2 mg/L), the honey flavoured rooibos (traditional / fermented) (331.0 ± 83.2 mg/L), the peach flavoured iced tea (powder) (298.5 ± 16.5 mg/L), the lemon flavoured iced tea (RTD) (371.5 ± 264.8 mg/L) and the peach flavoured iced tea (RTD) (323.7 ± 225.3 mg/L) respectively, while the total polyphenol content of the instant fruit punch and lemon flavoured iced tea (powder) was also significantly higher than that of all these samples respectively besides for that of the peach flavoured iced tea (powder).
The berry flavoured iced tea (RTD) had a significantly (p < 0.05) lower total polyphenol content (41.92 ± 79.37 mg/L) than that of all the commercially flavoured rooibos samples respectively, except for the camomile flavoured rooibos (traditional / fermented) (176.5 ± 46.2 mg/L). The total polyphenol content of the camomile flavoured rooibos (traditional / fermented) (176.5 ± 46.2 mg/L) and the peach flavoured iced tea (RTD) (323.7 ± 225.3 mg/L) were in addition also significantly (p < 0.05) lower than that of the honey flavoured rooibos (traditional / fermented) (331.0 ± 83.2 mg/L), the instant fruit punch flavoured iced tea (powder) (373.1 ± 30.4 mg/L) and the lemon flavoured iced tea (RTD) (371.5 ± 264.8 mg/L) respectively, while the total polyphenol content of the camomile flavoured rooibos (traditional / fermented) was significantly (p < 0.05) lower than that of the lemon flavoured iced tea (powder) (300.4 ± 42.1 mg/L) and that of the peach flavoured iced tea significantly (p < 0.05) higher than that of the lemon flavoured iced tea (powder) (see Table 4.16).
The commercially flavoured rooibos samples in tea bag form, i.e. camomile (traditional / fermented), honey (traditional / fermented) and lemon (traditional / fermented), delivered the highest flavonol content while instant fruit punch flavoured iced tea (powder) and instant fruit punch and lemon flavoured iced tea (powder) delivered the lowest flavonol content. The flavonol content of these commercially flavoured rooibos samples in tea bag form (fermented / traditional) (camomile, honey and lemon at 16.93 ± 4.07 mg/L, 21.04 ± 5.41 mg/L and 26.30 ± 4.85 mg/L respectively) were significantly (p < 0.05) higher than that of the other commercially flavoured rooibos samples respectively, except for the flavonol content of camomile flavoured rooibos (traditional / fermented) not being significantly (p > 0.05) higher than that of the lemon flavoured iced tea (RTD) (15.09 ± 9.70 mg/L). The lemon flavoured rooibos (traditional / fermented) in addition also yielded a significantly (p < 0.05) higher flavonol content than the camomile flavoured rooibos (traditional / fermented). The flavonol content of the lemon flavoured iced tea (RTD) (15.09 ± 9.70 mg/L) and the peach flavoured iced tea (RTD) (10.92 ± 6.68 mg/L) was significantly (p < 0.05) higher than that of the instant fruit punch flavoured iced tea (powder) (3.55 ± 4.72 mg/L) and the instant fruit punch and lemon flavoured iced tea (powder) (3.55 ± 3.99 mg/L). The lemon flavoured iced tea (RTD) had in addition a significantly (p < 0.05) higher flavonol content (15.09 ± 9.70 mg/L) than the instant apple fruit flavoured iced tea (powder) (5.13
± 1.04 mg/L) and the berry flavoured iced tea (RTD) (7.10 ± 4.47 mg/L) respectively (see Table 4.16).
Only two commercially flavoured rooibos samples delivered a flavanol content reading. The lemon flavoured rooibos (traditional / fermented) provided the higher flavanol content (at 65.26 ± 79.95 mg/L) and the honey flavoured rooibos (traditional / fermented) the lower (at 7.56 ± 3.22 mg/L) (see Table 4.16).
4.1.6 Rooibos sample(s) identification providing the highest total polyphenol content and