Antioxidant, antimicrobial and colour stability of curcumin-rich curcuma longa extract in free state and Poly Lactic Acid polymers

Abstract

Turmeric has been a popular spice throughout South Eastern Asia from earlier times which even until now are used in culinary as spice, traditional medicine, and even as dye. Its iconic yellow colour is caused by a compound called curcumin, which is known to have anti-inflammatory, antioxidant, and antimicrobial properties aside from various other health benefits. This research sought to investigate the potential of curcumin, which was extracted from turmeric (Curcuma longa) rhizome as a ‘Halalan Toyyiban’ alternative for synthetic colourant while studying its antioxidant and antimicrobial properties. The curcumin was extracted by using two extraction method, which then characterised and quantified using HPLC analysis. The extracted curcumin was tested for antimicrobial activity using the disc diffusion test, and tested for antioxidant property using the DPPH radical scavenging assay. The extracted curcumin, in both free state and in PLA polymer, was also tested for chromaticity stability where its colour changes was observed and analysed using the CIELab colour space system after it was exposed to different environmental factors as an indicator of its stability. The results showed that alkaline extraction produced higher curcumin yield compared to chemical based extraction. The extracted curcumin showed positive antimicrobial activity towards most of the tested microbes and the same inhibition activity for antioxidant test as shown from previous studies. The stability test using CIELab colour system showed that curcumin in both free state and in PLA polymer is very vulnerable towards degradation under the exposure of light, compared to any other environmental factor it was exposed to in this research. These results showed that curcumin retained, if not improved, its antimicrobial and antioxidant properties after being extracted from rhizome of Curcuma longa, and was easily degraded under the exposure of light.