Authors : Savita Senwar; Dr. Nasreen Anjum Khan

Volume/Issue : Volume 11 - 2026, Issue 8 - August

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Google Scholar : https://tinyurl.com/yuzchd26

DOI : https://doi.org/10.38124/ijisrt/26aug1090

Note : A published paper may take 4-5 working days from the publication date to appear in PlumX Metrics, Semantic Scholar, and ResearchGate.

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Abstract : This study compared fresh beetroot extract, a commercial dehydrated beetroot powder extract, and phenolphthalein side by side, using UV–Vis spectrophotometric scanning across a buffered pH range (1.3 - 11.5) and a weak acid-strong base titration (0.1 M CH₃COOH against 0.1 M NaOH). The fresh extract retained strong, stable absorbance at 480 nm and 535 nm across the acidic-to-neutral range, declining sharply only above pH 8-9, close to where phenolphthalein’s absorbance rose, an intersection marking a shared transition zone. The powdered extract, by contrast, showed a consistently weak, largely pH-insensitive signal, with its apparent absorption maximum shifted to 300 nm.

Keywords : Beetroot; Beta Vulgaris; Betalains; Betacyanin; Betaxanthin; Natural pH Indicator; UV-Vis Spectrophotometry; AcidBase Titration; Green Chemistry.

References :

1. K. A. Abdulsalam and I. A. Oladosu, “Methyl orange, an organic dye: Its health impact and sorptive removal from waste water,” Int. J. Prog. Sci. Technol., vol. 33, no. 1, pp. 150-160, 2022.
2. S. Samuel et al., “Novel eco-friendly acid-base indicators from innovative plant-based sources: Water-based extraction and applications in titration,” Sustain. Chem. Environ., 2024.
3. W. Maqsood et al., “Efficacy of plant extracts as green indicators in acid-base titrimetric analysis: Perspective towards green chemistry,” Microchem. J., p. 113221, 2025.
4. L. Yin et al., “Green analytical chemistry metrics for evaluating the greenness of analytical procedures,” J. Pharm. Anal., vol. 14, no. 11, p. 101013, 2024.
5. Z. Tamura, S. Abe, K. Ito, and M. Maeda, “Spectrophotometric analysis of the relationship between dissociation and coloration, and of the structural formulas of phenolphthalein in aqueous solution,” Anal. Sci., vol. 12, no. 6, pp. 927-930, 1996.
6. R. Pratiwi, D. S. Maharani, and S. G. Redjeki, “Betalain pigments: Isolation and application as reagents for colorimetric methods and biosensors,” Biosensors, vol. 15, no. 6, p. 349, 2025.
7. H. M. C. Azeredo, “Betalains: properties, sources, applications, and stability – a review,” Int. J. Food Sci. Technol., vol. 44, no. 12, pp. 2365-2376, 2009.
8. S. J. Calva-Estrada, M. Jiménez-Fernández, and E. Lugo-Cervantes, “Betalains and their applications in food: The current state of processing, stability and future opportunities in the industry,” Food Chem. Mol. Sci., vol. 4, p. 100089, 2022.
9. I. Sadowska-Bartosz and G. Bartosz, “Biological properties and applications of betalains,” Molecules, vol. 26, no. 9, p. 2520, 2021.
10. P. Kumari et al., “Natural pH indicators from flowers and vegetables: Extraction, characterization and comparative evaluation as eco-friendly alternatives to synthetic indicators,” Int. J. Pharmacol. Clin. Res., vol. 8, no. 6, pp. 48-52, 2026.
11. R. Abedi-Firoozjah et al., “Application of red cabbage anthocyanins as pH-sensitive pigments in smart food packaging and sensors,” Polymers, vol. 14, no. 8, p. 1629, 2022.
12. L. C. P. Gonçalves et al., “A comparative study of the purification of betanin,” Food Chem., vol. 131, no. 1, pp. 231-238, 2011.
13. Ž. Tarasevičienė, A. Paulauskienė, J. Černiauskienė, and A. Degimienė, “Chemical content and color of dried organic beetroot powder affected by different drying methods,” Horticulturae, vol. 10, no. 7, p. 733, 2024.
14. S. V. Gokhale and S. S. Lele, “Betalain content and antioxidant activity of Beta vulgaris: Effect of hot air convective drying and storage,” J. Food Process. Preserv., vol. 38, no. 1, pp. 585-590, 2014.
15. D. M. Lukitasari et al., “pH-dependent stability of major betalains in the encapsulated beetroot extracts (Beta vulgaris L.),” J. Food Sci., vol. 89, no. 5, pp. 2761-2773, 2024.