Abstract:
The current evidences show an increasing trend of sugar intake paralleled to the rise of
obesity and type 2 diabetes among the Thai population. Consumption of health beverages
derived from fruits and herbs which contain high amounts of added sugar may play a causative
role in development of these diseases. Furthermore, sugar fortification may affect antioxidant
stability in these beverages, including shelf life of them.
This study was to determine antioxidant capacity, total phenolics and sugar content of
selected Thai health beverages and then find an appropriate amount of fortified sugar in health
beverages by evaluating the effect of varying added sugar on antioxidant capacity and total
phenolic contents in selected pasteurized beverages with consumer acceptance in taste. The
storage effects of pasteurized and sterilized beverages on antioxidant capacity and total
phenolic compounds were also evaluated.
The beverage Brix in six pasteurized health beverages were increased by adding sugar
(0, 10, 15, 20, and 25 °Brix), and they were tested for consumer acceptance at minimum
amount of sugar fortification. They were also evaluated for antioxidant stability after 7 days of
storage at 5°C in a refrigerator. Twelve sterilized beverages were selected to evaluate
antioxidant stability after 1 and 3 months of storage at room temperature. The antioxidant
capacities were determined by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical
scavenging and Photochemiluminescence (PCL) assay. Folin-Ciocalteu assay and Nelson’s
reducing sugar test were used to determine total phenolic compounds and total sugar contents,
respectively.
There were decreasing trends in antioxidant capacity with increasing amounts of sugar
content among the samples, with significant inverse correlation by DPPH assay (r = -0.6 to -
0.9, p < 0.01), except sacred lotus root drink. With PCL assay, significant inverse correlation
in lipid soluble antioxidant capacity (ACL) values was found only in ginger drink (r = -0.5, p <
0.05). No significant change in total phenolic compounds was found, except in ginger drink.
Appropriately added sugar at 8 to 9 °Brix (18 – 24 g of sugar/serving) were well accepted in
the sensory test by general consumers (n = 30). There were significant losses in antioxidant
capacity measured by both assays and total phenolic compounds of pasteurized beverages by
storage duration in some kinds of beverage. Most sterilized beverages showed a good retention
of antioxidant capacity and total phenolic compounds during storage.
Even though adding sugars in the studied beverages may not have shown strong
correlation with antioxidant capacities, general consumers should perceive that not only
antioxidants but also excess caloric intake will be provided by fruit and herb beverages with
added sugars.