Starch recovery from turmeric powder (Curcuma longa) after ethanol curcumin extraction in comparison to the conventional method

Abstract

Recovery starch from organic waste significantly contributes to sustainable agricultural production. This study aimed to recover starch from the waste mimicking generated from the curcumin extraction by using ethanol. The physicochemical properties of the isolated starch such as microscopic morphology, Fourier transform infrared spectroscopy, X-ray diffraction, total starch, iodine binding capacity of starch, curcumin content determined by high-performance liquid chromatography were compared to that of starch obtained from the conventional method of extraction from the fresh rhizome. The results showed that the starch obtained from the fresh rhizome had a higher yield (21.3% vs. 8.5%) compared to that of starch isolated from the turmeric powder after extracting curcumin. The total starch analysis indicated that the former starch had a higher purity (98% vs. 77%, dw). The SEM imaging showed that both starches had irregular shapes with a thick flat and smooth surface. Although the starch isolated from the turmeric powder showed the dedicated properties of starch, the peak intensity and crystalline structure were remarkably decreased, observed under FTIR and X-ray diffraction analyses, respectively. The pasting analysis showed a clear change in starch obtained from the turmeric powder after ethanol extracting curcumin since a low peak viscosity was recorded. The HPLC curcumin quantification showed that both starches had a very low residue of curcumin (18.4 mg/100 g and 66.5 mg/100 g, dw) after isolation. The process of recovery starch after curcumin extraction from turmeric would be further improved to prevent the changes in physicochemical properties and for better yield.