Investigation of total polyphenol, antioxidant activity, and levels of metals in Ethiopian commercial beers

Abstract

Total polyphenol, antioxidant activity, and heavy metal contents in selected Ethiopian beers (Dashen= B1, Harar = B2, Habesha= B3, Saint George= B4, and Walya= B5) were investigated. The average concentration of total phenolic content in B1, B2, B3, B4, and B5 were found to be 219.80, 206.09, 190.24, 193.00, and 212.10 mg GAE/L, respectively. The obtained results showed that B1 contained significantly highest total polyphenol content (219.80±2.83 mg/L) and showed the highest radical scavenging capacities (84.16±0.65). According to Pearson’s correlation between polyphenol extract with antioxidant activities, suggested that phenolic compound in beer were contributor to antioxidant activity. Similarly, all the beer samples were analyzed for Cd, Cr, Cu, Ni, and Pb with flame atomic absorption spectrophotometer. The total metal concentrations of Cd, Cr, Cu, Ni, and Pb were found to be in the range of (ND–0.022 mg/L), (0.02 −0.041), (0.023-0.054), (ND-0.064), and (ND-0.022 mg/L), respectively. The efficiency of the procedure was validated by spiking and the percent recovery of the metals varied from 90.9 to 104.3%.

Keywords:

• Beers
• polyphenol
• antioxidant
• metals

PUBLIC INTEREST STATEMENT

The growth of Ethiopian population has got an increase in the consumption beer from time to time. This leads to beer market competition throughout the country as the consumer beer brand preference gets improved. Beer contains a variety of polyphenols which can be important for its chemical stability and shelf life. The ingredients hops, malt, and water; and brewing processes are the sources of naturally occurring antioxidant compounds and trace metals. Recently, consumers are paying their attention toward the importance of dietary antioxidant components for the betterment of human health. There is, however, very limited or no published information on the total polyphenol content, antioxidant activities, and levels of metals of Ethiopian beers. This work investigated the total polyphenol content, antioxidant activities, and levels of metals. The results showed that Ethiopian Beers could be considered as potential sources of phenols that have got promising potential antioxidant activities. The levels of metals in beers were also found under maximum permissible limit given many countries.

Conflict of Interests

The authors declare that there is no conflict of interest regarding the publication of this paper.

Additional information

Notes on contributors

Molla Tefera

Dr. Molla Tefera (First author) is an assistant professor in analytical chemistry at the University of Gondar, Chemistry Department, Ethiopia. He has published over 10 articles in reputable journals and his research lines primarily on electrochemical method of developing sensors for the determination of electroactive substances in food, environment and pharmaceuticals. Besides, he is working on bioactive characteristics and develops analytical methods for assessment of the level and removal methods of selected pollutants like metals, pesticides, and aflatoxins in food and environmental samples.