Efficiency of CaO usage as a pre-clarification adsorbent in aqueous stevia extract
Özet
Stevia extract, when untreated, has a dark brown appearance, mainly because of the
presence of impurities. CaO nanoparticles are effectively used as an adsorbent to
purify the desired chemical compounds, decolorize the liquids, etc. in the food
industry. In this study, the efficiency of CaO nanoparticle as a pre-clarification
adsorbent was investigated for the removal of impurities in aqueous stevia extract
before the purification process. For this purpose; dry stevia leaves were ground with
distilled water (1:25, dry leaf:water, w/w) and kept in a water bath at 40 °C for 30
minutes. After the extraction process, the samples were centrifuged at 2900xg for 25
minutes at 25 °C. Then the extracts were treated with different concentrations of
CaO. Steviol glycoside composition of the CaO-treated and untreated samples
(control group) were analyzed by HPLC. According to the results, it was observed
that the obtained stevia extracts were clearer (had lower turbidity values), especially
when treated with CaO at the level of 0.15%, and no concentration loss occurred in
terms of the glycosides analyzed in the extracts. Besides, the peak areas of both
glycosides increased proportionally when CaO adsorbent was added to the main
process. For further studies, investigation of other CaO-related parameters such as
contact time, ambient conditions (pH, temperature, etc.) is recommended to be tried
to increase the efficiency of this adsorbent in stevia processing.
