Impact of Thermal, Agitation and Microwave Assisted Extraction Techniques on Ascorbic Acid Content of Red Beet (Beta vulgaris L)

Abstract

The processing techniques for food product incorporation or consumption, generally influences
the stability of ascorbic acid, same is true for red beet, because ascorbic acid is a natural water-soluble
vitamin and highly sensitive to heat, light and air. The objective of the study was to investigate the influence
of extraction techniques viz., thermal, agitation assisted and microwave assisted extraction on ascorbic acid
content of red beet using different solvent compositions like distil water, distil water with 0.5 % citric acid,
20% ethanol, 20% ethanol with 0.5 % citric acid, 50% ethanol and 50% ethanol with 0.5 % citric acid.
The impact of extraction techniques was evaluated on the basis of different temperatures (40, 50 and 60 oC),
agitation speeds (150, 170 and 190 rpm) and microwave power levels (160, 320 and 480 W). With
Spectrophotometric results it was found that highest ascorbic acid content was in agitation assisted extraction
as 104.0132 µg/g dry weight (DW) at 190 rpm in T5 sample (where 50 % ethanol used as solvent) followed by
48.1247 µg/g DW in microwave assisted extraction in T6 (50% ethanol + 0.5% citric acid) and 20.4423 µg /g
DW was obtained in thermal extraction at 40oC followed by 20.0757 at 60oC in T5 (where 50 % ethanol used
as solvent). The results indicate that solvent type and extraction methods significantly influenced ascorbic
acid content extracted in the samples.