The food industry has traditionally used sugar (sucrose) as a sweetening agent; however the dietary and health demands are continuing to expand the market for sweeteners as an alternative to sucrose. The leaves of Stevia rebaudiana are rich source of glycosides that have sweet taste with low calorific value. The study highlights extraction of steviosides from leaves using pressurised hot water extractor, followed by purification and concentration of the sweet glycosides through ultra (UF) and nano (NF) filtration membrane in obtaining high purity steviosides. After the final purification process the stevioside content was 9.05 g per 100 g and rebaudioside A 0.2 g per 100 g stevia leaf, with total purity of stevioside 97.66% by HPLC at total operation time of 7 h. This process also improved the potency of sweetness and palatability profile when compare with other commercially available steviosides. Thus, the methodology developed establishes simple, in-expensive and eco-friendly process in obtaining pure steviosides.

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Asymmetric reduction of the heteroaryl prochiral ketones to corresponding chiral alcohols by Daucus carota was studied. The study highlights selective bioreduction of different substituted heteroaryl ketones (1a -1j) to their respective chiral alcohols (2a -2j) using plant dehydrogenase enzymes present in Daucus carota in good yields (60% -95%) and enantioselectivity (76% -99%) with S-form configuration. The results obtained confirm that the membrane bound dehydrogenase enzyme has broad substrate specificity and selectivity in catalyzing both six and five membered heteroaryl methyl ketones. The present methodology demonstrates promising and alternative green route in the synthesis secondary chiral alcohols of biologically importance in a simple, inexpensive and eco-friendly process.

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