Studies on the levels of total polyphenol, flavonoid, tannin and antioxidant capacity of selected Ethiopian fermented traditional beverages
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Date
2015-06
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Addis Ababa Universty
Abstract
The purposes of this study were to determine total phenolic content (TPC), total
flavonoids content (TFC), total tannin content (TTC), and total antioxidant activity (TAA) and to
compare these parameters of Ethiopian traditional alcoholic beverages from different origins of
Ethiopia within the same sample type and between different sample types. For these purposes,
methanolic extracts (70%) were prepared for semi-solid samples. Total phenolic content (TPC)
was determined by Folin-Ciocalteu’s method, total flavonoids content (TFC) was determined by
aluminium chloride (AlCl3) method, total tannin content (TTC) was determined by indirect
method precipitating with gelatin, protein while DPPH radical scavenging activity method was
used to determine the total antioxidant activity (TAA). The total phenolic content (TPC) obtained
in gallic acid equivalent, GAE mg L-1 was: korefe (285-326), tej (369–390) and tella (435–459);
the total flavonoids content (TFC) obtained in catechin equivalent, CE mg L-1 was: korefe (190-
199), tej (183–190) and tella (211–216); the total tannin content (TTC) obtained in tannic acid
equivalent, TAE mg L-1 was: korefe (19.9–25.9), tej (17.9–19.4) and tella (28.8–30.8) and the
total antioxidant activity (TAA) obtained in ascorbic acid equivalent, AAE mgL-1 was: korefe
(479–498), tej (465–479) and tella (541–561). Tella exhibited a highest scavenging effect and
the reducing capability on DPPH solution absorbance compared to others. Similarly, total
phenolic content (TPC), total flavonoids content (TFC) and total tannin content (TTC) also
showed that tella had the highest content than the rest beverages. Statistically, Pearson
correlation showed there were positive correlations between total phenolic content (TPC), total
flavonoids content (TFC) and total tannin content (TTC) with antioxidant capacity assayed by
DPPH radical scavenging assay (r = 0.969, r = 0.931 and r = 0.944, respectively). In brief, all
phenolic parameters measured and antioxidants were highly remarkable in the sequence of tella
> korefe > tej. At 95% confidence level one way ANOVA displayed that the levels of total
polyphenol, flavonoid, tannin and antioxidant activity are significantly different between unlike
sample types and the magnitude of these bioactive chemicals are in comparable amount with the
few beverages reported in the literature
KEY WORDS: Polyphenol level, Flavonoid level, Tannin level, Antioxidant capacity,
Ethiopian traditional alcoholic beverages
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Keywords
Polyphenol level, Flavonoid level, Tannin level, Antioxidant capacity, Ethiopian traditional alcoholic beverages