Abstract

  The aim of the present work was to quantify caffeine and total phenolic content and to evaluate the antioxidant activity in commercially available black tea, green tea, Turkish coffee and traditional Omani qahwa. Aqueous extracts of tea and coffee samples prepared by decoction were subjected to the phytochemical screening test for phenols and caffeine. Caffeine in the samples was quantified with the help of a linear regression equation obtained from the standard plot. Total phenolic and flavonoid contents in the tea and coffee were estimated colorimetrically. Antioxidant activity of the samples was investigated by DPPH (1, 1 diphenyl picrylhydrazyl) free radical assay and phosphomolybdenum methods. All the test extracts showed the presence of phenolic compounds and caffeine. The results indicated a variation in caffeine content, phenolic content, flavonoid content and antioxidant activity between the two extracts and among same extracts with different brand names. In general, Mumtaz black tea was found to contain the highest caffeine (24.44 mg/g) and phenolic content (8.27 mg/g of GAE). It also showed the highest total antioxidant activity (10.46 mg/g of ascorbic acid equivalent) but surprisingly its flavonoid content and antioxidant activity by DPPH method was lower than other samples. Tea was found to be richer in phenols and caffeine but Omani qahwa showed better antioxidant activity. It can be concluded that phenolic content and the antioxidant activities depend on the origin, brands and additives of these beverages that may lead to variation in the content and bioactivity.

Keywords: Turkish and Omani Qahwa; Black Tea; Green Tea; Phenols; Antioxidant; Caffeine

References

1. Daniele W., et al. “Systematic review of the potential adverse effects of caffeine consumption in healthy adults, pregnant women, adolescents, and children”. Food and Chemical Toxicology 1 (2017): 585-648.
2. Jeszka-Skowron M., et al. “Chlorogenic acids, caffeine content and antioxidant properties of green coffee extracts: influence of green coffee bean preparation”. European Food Research and Technology 242 (2016): 1403-1409.
3. Khan N and Mukhtar H. “Tea and health: studies in humans”. Current Pharmaceutical Design 34 (2013): 6141-6147.
4. Evans WC., et al. “Trease and Evans pharmacognosy (16^th Edition)”. Edinburgh; New York: Saunders/Elsevier (2009).
5. Ziyin Y., et al. 2013. “Recent studies of the volatile compounds in tea”. Food Research International 2 (2013): 585-599.
6. Chacko SM., et al. “Beneficial effects of green tea: A literature review”. Chinese Medicine 5 (2010): 13.
7. Jane VH and Balz F. “Coffee and Health: A Review of Recent Human Research”. Critical Reviews in Food Science and Nutrition 2 (2006): 101-123.
8. Chanyarin S., et al. “Effects of roasting degree on radical scavenging activity, phenolics and volatile compounds of Arabica coffee beans (Coffea arabica cv. Catimor)”. International Journal of Food Science and Technology 46.1 (2011): 2287-2296.
9. Poole RL and Tordoff MG. “The Taste of Caffeine”. Journal of Caffeine Research2 (2017): 39-52.
10. Pawar P. “Green Tea and Weight Loss: An update (Meta-Analysis)”. International Journal of Biotechnology and Biomedical Sciences 1 (2015): 21-24.
11. Li X., et al. “Tea consumption and risk of ischaemic heart disease”. Heart1 (2017): 783-789.
12. Zhang Y., et al. “Coffee consumption and the incidence of type 2 diabetes in men and women with normal glucose tolerance: the Strong Heart Study”. Nutrition, Metabolism and Cardiovascular Diseases 6 (2011): 418-423.
13. Lopez-Barrera DM., et al. “Spent coffee grounds, an innovative source of colonic fermentable compounds, inhibit inflammatory mediators In vitro”. Food Chemistry Journal1 (2016): 282-290.
14. Iriondo De Hond A., et al. “Coffee Silver skin Extract Protects against accelerated aging caused by oxidative agents”. Molecules Journal6 (2016): 721.
15. Park JB. “Finding Potent Sirt Inhibitor in Coffee: Isolation, Confirmation and Synthesis of Javamide-II (N-Caffeoyltryptophan) as Sirt1/2 Inhibitor”. PLOS ONE3(2016): e0150392.
16. Zhao Y., et al. “Black tea consumption and serum cholesterol concentration: Systematic review and meta-analysis of randomized controlled trials”. Clinical Nutrition4 (2015): 612-619.
17. Zhang ZF., et al. “Updated association of tea consumption and bone mineral density: A meta-analysis”. Medicine Journal 96 (2017): e6437.
18. Jose Manuel L and Paulo Eduardo SM. “Phenolic compounds of green tea: Health benefits and technological application in food”. Asian Pacific Journal of Tropical Biomedicine 8 (2016): 709-719.
19. Odzakovic B., et al. “Effect of roasting degree on the antioxidant activity of different Arabica coffee quality classes”. Acta Scientiarum Polonorum Technologia Alimentaria 4 (2016): 409-417.
20. Richelle M, et al. “Comparison of the antioxidant activity of commonly consumed polyphenolic beverages (coffee, cocoa, and tea) prepared per cup serving”. Journal of Agriculture and Food Chemistry 2 (2001): 3438-3442.
21. Harborne JB. “Phytochemical Methods: A Guide to Modern Techniques of Plant Analysis”. (1 Edition) Chapman and Hall, London (1973).
22. Tadelech A and Gholap AV. “Characterization of caffeine and determination of caffeine in tea leaves using UV-visible spectrometer”. African Journal of Pure and Applied Chemistry 1 (2011): 1-8.
23. Mohamed Al-F., et al. “Comparison of Antioxidant Activity, Anthocyanins, Carotenoids, and Phenolics of Three Native Fresh and Sun-Dried Date (Phoenix dactylifera) Varieties Grown in Oman”. Journal of Agricultural and Food Chemistry 53.19 (2005): 7592-7599.
24. Soysa C., et al. “Extraction Kinetics of phytochemicals and antioxidant activity during black tea (Camellia sinensis ) brewing”. Nutrition Journal 14.1 (2015): 74.
25. Sethiya NK., et al. “The total antioxidant content and radical scavenging investigation on 17 phytochemical from dietary plant sources used globally as functional food”. Biomedicine and Preventive Nutrition 3 (2014): 439-444.
26. Mirela K., et al. “Phenol content and antioxidant activity of green, yellow and black tea leaves”. Chemical and Biological Technologies in Agriculture 1 (2015): 1-6.
27. Jenna M., et al. “Caffeine Content of Brewed Teas”. Journal of Analytical Toxicology4 (2008): 702-704.
28. Bansode PA., et al. “Spectrophotometric determination of total phenolic content of some commonly consumed teas in India”. Bionano Frontier1 (2014.): 78-80.
29. Mitchell D C., et al. “Assessing dietary exposure to caffeine from beverages in the U.S. population using brand-specific versus category-specific caffeine values”. Food and Chemistry Toxicology 80 (2015): 247-252.
30. Kopjar M., et al. “Phenol content and antioxidant activity of green, yellow and black tea leaves”. Chemical and Biological Technologies in Agriculture1 (2015): 1-6.

Citation

Citation: Dhanalakshmi UM, Shah A Khan., et al. “In Vitro Antioxidant Activity, Spectrophotometric Determination of Caffeine, Total Phenol and Flavonoid Contents in Traditional Omani Qahwa in Comparison with Green and Black Tea".Acta Scientific Nutritional Health 4.10 (2020): 50-56.

Copyright

Copyright: © 2020 Dhanalakshmi UM, Shah A Khan., et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.