Abstract
The effect of different drying treatments of stevia leaves on antioxidant activity, ferric
reducing power (FRAP), total phenolic content as well as stevioside and rebaudioside
A content were evaluated. Drying treatments that were applied were oven drying (80°C
and 60°C), sun drying, microwave drying and freeze drying. Results of all samples were
compared with fresh leaves. Antioxidant activity of dried leaves was evaluated using
DPPH radical scavenging activity and ferric reducing power (FRAP) by
spectrophotometer. Stevioside and rebaudioside A content were evaluated using HPLC.
Among all drying treatments, microwave was found to be the highest in scavenging the
DPPH radical activity with no significant different with freeze dried and fresh leaves
(P> 0.05). Inhibitory concentration at 50% of microwaved leaves was the lowest
compared to other dried leaves. In addition to that, microwave dried leaves exhibit
highest total phenolic content at 53.95 ± 2.83 mg/g gallic acid equivalent. As for
stevioside and Rebaudioside A, no degradation happened in comparison with fresh
leaves after drying treatment. Stevioside appeared to be higher in content than
rebaudioside A. This indicate that microwave can be good drying method, without
altering the stevioside and rebaudioside A content inside the leaves, thus maintaining
the sweetening properties of the leaves.
Ariffah Abdul Halim, Zamzahaila Mohd Zain, Aidilla Mubarak, Fauziah Tufail Ahmad. (2019) Effect of different drying methods on antioxidant properties, stevioside and rebaudioside A contents of stevia (Stevia rebaudiana bertoni) leaves, Asian Journal of Agriculture and Biology, Volume 7, Issue 1.
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