CHAPTER 4 RESULTS
4.3 Effect of thermal processing on the total polyphenol and carotenoid contents and the TAC of the soup recipe formulations
4.3 Effect of thermal processing on the total polyphenol and carotenoid contents and
4.3.1 Chunky vegetable soup
As shown in Table 4.3 thermal processing resulted in a significant (p < 0.05) increase in the total polyphenol content of the thermally processed control chunky vegetable soup recipe formulation when compared to the raw control soup recipe formulation. The experimental soup recipe formulations also both increased in total polyphenol contents after thermal processing with the total polyphenol contents in the control and both the experimental recipe formulations significantly higher (p < 0.05 for each) when compared to the raw soup recipe formulations containing either water, fermented or unfermented rooibos. The increase in polyphenol content after thermal processing in the experimental soup recipe formulations was the highest with the use of unfermented rooibos as the liquid ingredient. On thermal processing the polyphenol content increased with 3 mg GAE/100 g in the fermented rooibos soup recipe formulation and with 8 mg GAE/100 g in the unfermented rooibos soup recipe formulation.
Thermal processing had a detrimental effect on the carotenoid content of the control and both the experimental chunky vegetable soup recipe formulations (Table 4.3). The carotenoid content with thermal processing significantly decreased (p < 0.05 for each) in the raw and cooked control and experimental soup recipe formulations. The decrease in the carotenoid content was the greatest with thermal processing of the raw control soup recipe formulation (- 563 µg/100 g), followed by the unfermented rooibos experimental soup recipe formulation (- 509 µg/100 g) and with the lowest decline occurring in the raw fermented rooibos experimental soup recipe formulation (- 465 µg/100 g).
There was a slight although not significant (p > 0.05) increase in the H-ORAC after thermal processing of the cooked control chunky vegetable soup recipe formulation compared to the raw control soup recipe formulation. Thermal processing of the soup recipe formulation when water was substituted with fermented rooibos did not result in a significant (p > 0.05) increase in H-ORAC when compared to the raw recipe formulation, while thermal processing of the experimental recipe formulation substituted with unfermented rooibos, resulted in a significantly (p < 0.05) higher H-ORAC, when compared to the raw experimental soup recipe formulation. Thermal processing significantly (p < 0.05 for each) reduced the L-ORAC of the cooked control and experimental chunky vegetable soup recipe formulations when compared to the raw control and the experimental recipe formulations. Thermal processing increased the TAC of the control and experimental chunky vegetable soup recipe formulations;
however, the increase was only significant (p < 0.05) for the thermally processed soup recipe
formulation containing unfermented rooibos versus the raw recipe formulation containing unfermented rooibos as was found for the increase in the H-ORAC (Table 4.3).
A strong correlation was found between the TAC and the total polyphenol content (r = 0.999) and the H-ORAC (r = 1.000) of the chunky vegetable soup recipe formulation, whereas the correlation between the TAC and the L-ORAC (r = 0.088) and the carotenoid content (r = 0.073) was low.
4.3.2 Butternut soup
As shown in Table 4.3 thermal processing also resulted in a significant (p < 0.05) increase in the total polyphenol content of the cooked control butternut soup recipe formulation when compared to the raw control recipe formulation. The experimental soup recipe formulations also both increased in total polyphenol contents after thermal processing with the total polyphenol contents in the control and both the experimental recipe formulations significantly higher (p < 0.05 for each) when compared to the raw soup recipe formulations containing either water, fermented or unfermented rooibos. The increase in the total polyphenol content on thermal processing was the highest (+ 6 mg GAE/100 g) for the experimental recipe formulation containing fermented rooibos.
Thermal processing significantly (p < 0.05 for each) reduced the carotenoid content of the cooked control and both the cooked experimental butternut soup recipe formulations compared to the raw control and the raw experimental soup recipe formulations (Table 4.3).
This detrimental effect on the carotenoid content of the control and both the experimental butternut soup recipe formulations was also found with the chunky vegetable soup control and experimental recipe formulations (see 4.3.1).
There was a slight although not significant (p > 0.05) increase in the H-ORAC after thermal processing of the cooked control butternut soup recipe formulation compared to the raw control butternut soup recipe formulation. The experimental soup recipe formulations also both increased in H-ORAC after thermal processing with the H-ORAC of both experimental recipe formulations significantly higher (p < 0.05 for each) when compared to the raw soup recipe formulations containing either fermented or unfermented rooibos. Thermal processing significantly (p < 0.05 for each) decreased the L-ORAC of the cooked control and both experimental butternut soup recipe formulations when compared to the raw control and the experimental recipe formulations as was found for the carotenoid contents (Table 4.3) and the L-ORAC of the cooked control and both the experimental chunky vegetable soup recipe formulations (see 4.3.1).
Thermal processing increased the TAC of the control butternut soup recipe formulation;
however, this increase was not significant (p > 0.05). The experimental soup recipe formulations’ TAC also both increased after thermal processing, with the TAC of both experimental recipe formulations significantly higher (p < 0.05 for each) when compared to the raw soup recipe formulations containing either fermented or unfermented rooibos (Table 4.3).
As for the chunky vegetable soup recipe formulation a strong correlation existed between the TAC and the total polyphenol content (r = 0.909) and the H-ORAC (r = 1.000) for the butternut soup recipe formulation with the correlation between the TAC and the L-ORAC (r = -0.577) and the carotenoid content (r = -0.199) again low.
4.3.3 Chicken noodle soup
Thermal processing significantly (p < 0.05) increased the total polyphenol content of the cooked control chicken noodle soup recipe formulation compared to the raw soup mixture.
Thermal processing of the chicken noodle soup experimental recipe formulations when water was substituted with fermented or unfermented rooibos resulted in significantly decreased (p
< 0.05 for each) total polyphenol contents of these soup recipe formulations. The loss in the polyphenol content after thermal processing in the unfermented rooibos experimental soup recipe formulation was double (- 10 mg GAE/100 g) compared to the loss in the fermented rooibos experimental soup recipe formulation (- 5 mg GAE/100 g) (Table 4.3).
No carotenoids could be detected in either the thermally processed control or experimental chicken noodle soup recipe formulations (Table 4.3). Thermal processing therefore extensively reduced the carotenoid content of the cooked control and both the experimental chicken noodle soup recipe formulations compared to the raw control and the raw experimental soup recipe formulations carotenoid content.
There was a significant (p < 0.05) increase in the H-ORAC after thermal processing of the cooked control chicken noodle soup recipe formulation compared to the raw control soup recipe formulation. The opposite results occurred for the experimental recipe formulations.
The H-ORAC of the chicken noodle experimental soup recipe formulations on thermal processing was significantly lower (p < 0.05 respectively) than that of the raw soup mixtures.
The decrease in the H-ORAC on thermal processing was somewhat higher in the experimental soup recipe formulation with fermented rooibos with it decreasing 715 µmole
TE/100 g compared to the experimental soup recipe formulation with unfermented rooibos that decreased by 666 µmole TE/100 g with thermal processing (Table 4.3).
Thermal processing significantly (p < 0.05 for each) decreased the L-ORAC of the cooked control and both experimental chicken noodle soup recipe formulations when compared to the raw control and the experimental recipe formulations. Thermal processing resulted in a decrease of the L-ORAC to between 0 and 1 µmole TE/100 g measured in the three cooked soup mixtures. The highest decrease on thermal processing occurred in the fermented rooibos (- 22 µmole TE/100 g) followed by the control (- 22 µmole TE/100 g) soup recipe formulation and the lowest decrease in the unfermented rooibos (-19 µmole TE/100 g) soup recipe formulation (Table 4.3).
The TAC of the raw control soup recipe formulation significantly (p < 0.05) increased on thermal processing by 366 µmole TE/100 g. There was a significant (p < 0.05 for each) decrease in the TAC of the experimental soup recipe formulations on thermal processing compared to the TAC of the raw experimental recipe formulations. The TAC of the experimental soup recipe formulation with the fermented rooibos herbal tea decreased by 736 µmole TE/100 g and the TAC of the experimental soup recipe formulation with the unfermented rooibos herbal tea by 684 µmole TE/100 g after thermal processing (Table 4.3).
These changes in the TAC of the control and experimental soup recipe formulations correspond to the changes in the H-ORAC of the soup recipe formulations on thermal processing.
A strong correlation also existed between the TAC (r= 0.900) and the H-ORAC (r = 1.000) for the chicken noodle soup recipe formulation with the correlation between the TAC and the L-ORAC (r = 0.38) and the carotenoid content (r = 0.39) again low.
CHAPTER 5