ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Digital image-based quantification of ethanol in distilled spirits using red cabbage (Brassica oleracea) extract

Harriet Jane R. Caleja-Ballesteros and Joel I. Ballesteros

Institute of Chemistry, University of the Philippines, Diliman, Quezon City, Philippines

E-mail: hrcaleja@up.edu.ph

Received: 17 March 2023  Accepted: 11 August 2023

Abstract:

Anthocyanins are currently used in green chemistry as a coloring agent for colorimetric analysis due to their ability to change color in different pH environments. A red cabbage (Brassica oleracea)-based digital image analytical method for the determination of ethanol concentration is proposed in this study. Hydroxide ions were added to change the color of the extract. The addition of ethanol in the red cabbage–NaOH mixture affects the degree of ionization of the hydroxide solution. The effect of the addition of varying concentrations of ethanol was digitized into RGB channel values. The change in the R-channel value was found to be linear versus the concentration range of alcohol from 5.0 to 50.0%(v/v), and the limit of detection obtained was 2.97%(v/v). The proposed method was also applied to the distilled spirit samples, and the results were validated using Gas Chromatography with Flame Ionization Detector (GC-FID) measurements. The difference in the results from the two methods was not statistically significant which makes the proposed method a cheaper, simpler, and greener alternative tool in the analysis of ethanol in distilled spirits.

Graphical Abstract

Keywords: Green chemistry; Red cabbage; Anthocyanin; Ethanol; Distilled spirit; Digital image colorimetry

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-03034-5

Chemical Papers 77 (12) 7977–7984 (2023)