AN INVESTIGATION ON THE POTENTIAL OF EXTRACTING NATURAL DYES FROM BEETROOT AND TURMERIC

Abstract

Today, owing to the environmental and health drawbacks associated with synthetics dyes, stringent standards are imposed by many countries including Mauritius. Following this issue, great enthusiasm is evoked in the rival of natural colourants which are nowadays gaining popularity due to their green approach. Two well-known, readily available and low cost natural dyes bearing plants in Mauritius namely beetroot (Beta Vulgaris) and turmeric (Curcuma Longa) were opted in this study. A comparative study between the extraction of betalains and curcuminoids from the two plants were systematically evaluated between conventional magnetic stirring (MS) and novel microwave assisted extraction techniques (MAE). The optimum operating conditions to yield maximum hues from the two plant species were 50 % aqueous ethanol, agitation speed of 160 rpm, microwave power of 320 W, particle sizes of 0.45 mm and a solid to solvent ratio (SSR) of 1/35. Under the optimised conditions, the results demonstrated that the extraction yields for MAE were higher and more efficient than the conventional one. Consequently, for MS extraction of beetroot and turmeric, the maximum yields recovered were 69.55 % and 48.00 %, whilst the yield for MAE extraction rose to 89.64 % and 79.73 % respectively. Using the experimental data, this research also explored Peleg’s and Elovich’s kinetic models of dyes extraction.