Antioxidant activity and the most abundant phenolics in commercial dark beers

Figures & data

Table 1. Characteristics of nine commercial dark beers.

Brand of dark beer	Original extract* [%]	Alcohol content* [%,v/v]	Country of origin
B1 Andechs Doppelbock Dunkel	18.5	7.1	Germany
B2 Erdinger Weissbier Dunkel	12.9	5.6	Germany
B3 Flötzinger Bräu Export Dunkel	12.6	5.3	Germany
B4 Flötzinger Bräu Weizen Dunkel	12.5	5.5	Germany
B5 Krušovice	10.0	3.8	Czech
B6 Zlatopramen	11.0	4.6	Czech
B7 Samson	10.0	3.6	Czech
B8 Kozel	10.0	3.8	Czech
B9 Porter Żywiec	21.4	9.5	Poland

*The values according to the producers declaration.

Figure 1. Chromatogram of the polyphenol standards mixture, at 280 nm: 1—gallic acid, 2—chlorogenic acid, 3—vanilic acid, 4—caffeic acid, 5—syringic acid, 6—p-coumaric acid, 7—ferulic acid, 8—synapic acid, 9—quercetin, and 10—kaempferol.

Figure 2. Chromatogram of dark beer Erdinger Weissbier after hydrolysis, at 280 nm.

Figure 3. Chromatogram of the polyphenol standards mixture, at 340 nm: 2—chlorogenic acid, 4—caffeic acid, 6—p-coumaric acid, 7—ferulic acid, 8—synapic acid, 9—quercetin, and 10—kaempferol.

Table 2. Antioxidant activity of the dark beer samples measured using ABTS and DPPH assays.

Nonhydrolyzed beer sample	ABTS [mMT/dm^Citation3	DPPH [mMT/dm^Citation3]	Hydrolyzed beer sample	ABTS [mMT/dm^Citation3]	DPPH [mMT/dm^Citation3]
B1	0.61^e ± 0.04	0.40^c,d ± 0.01	B1	4.60^c ± 0.28	3.53^b ± 0.10
B2	0.51^c ± 0.00	0.35^b,c ± 0.00	B2	3.20^a ± 0.00	3.23^b ± 0.05
B3	0.54^d ± 0.01	0.40^c,d ± 0.00	B3	4.11^b ± 0.58	3.16^b ± 0.23
B4	0.39^b ± 0.04	0.35^b ± 0.02	B4	4.09^b ± 0.11	3.22^b ± 0.20
B5	0.25^a ± 0.03	0.23^a ± 0.03	B5	2.73^a ± 0.24	2.60^a ± 0.12
B6	0.55^d ± 0.06	0.37^b,c ± 0.00	B6	4.19^b,c ± 0.26	3.16^b ± 0.02
B7	0.64^f ± 0.00	0.42^d ± 0.01	B7	4.71^c ± 0.40	3.76^c ± 0.18
B8	0.61^e ± 0.01	0.40^c,d ± 0.00	B8	4.40^b,c ± 0.20	3.10^a,b ± 0.14
B9	0.72^g ± 0.00	0.67^e ± 0.00	B9	3.99^b ± 0.01	3.17^b ± 0.01
Average	0.54	0.40		4.00	3.21

Mean values from two repetitions ± standard deviations.

Means in the same column with different superscript are significantly different (α = 0.05).

mMT/dm³—mmol of trolox per 1dm³.

Table 3. Phenolic compounds determined by HPLC in the dark beers samples expressed in mg per 1 dm³.

Nonhydrolyzed beer sample	Gallic acid	Caffeic acid	p-Coumaric acid	Ferulic acid	Synapic acid	Quercetin	Kaempferol
B1	6.34^f ± 0.29	0.06^b ± 0.00	0.55^h ± 0.01	4.03^g ± 0.07	0.80^d ± 0.01	0.04^c ± 0.00	0.06^a ± 0.00
B2	1.33^b ± 0.01	0.10^d ± 0.00	0.21^e ± 0.00	2.37^e ± 0.03	0.67^c ± 0.01	0.02^a ± 0.00	0.09^b ± 0.00
B3	3.48^d ± 0.12	0.05^b ± 0.00	0.09^b ± 0.00	1.50^c ± 0.01	0.46^b ± 0.00	0.03^b ± 0.00	0.11^c ± 0.00
B4	1.46^b ± 0.03	0.06^b ± 0.00	0.04^a ± 0.00	0.34^a ± 0.02	0.42^b ± 0.05	0.05^d ± 0.00	0.07^a ± 0.00
B5	0.92^a ± 0.01	0.03^a ± 0.00	0.11^c ± 0.01	0.92^b ± 0.12	0.21^a ± 0.00	0.03^b ± 0.00	0.06^a ± 0.00
B6	2.25^d ± 0.18	0.14^e ± 0.00	0.38^g ± 0.01	2.17^e ± 0.30	0.59^c ± 0.01	0.06^e ± 0.01	0.10^b ± 0.01
B7	1.28^a,b ± 0.05	0.07^c ± 0.01	0.26^f ± 0.00	1.80^d ± 0.09	0.42^b ± 0.00	0.03^b ± 0.00	0.16^d ± 0.00
B8	3.31^e ± 0.32	0.07^c ± 0.01	0.17^d ± 0.00	1.35^c ± 0.01	0.42^b ± 0.01	0.06^e ± 0.00	0.10^b ± 0.00
B9	1.76^c ± 0.04	0.16^f ± 0.00	0.58^i ± 0.00	3.50^f ± 0.04	0.99^e ± 0.06	0.06^e ± 0.00	0.18^e ± 0.01
Average	2.46	0.08	0.27	1.99	0.55	0.04	0.10
Hydrolyzed beer sample
B1	8.08^f ± 0.09	1.96^e ± 0.02	1.83^f ± 0.03	25.86^f ± 1.01	7.87^f ± 0.15	1.70^g ± 0.06	0.29^f ± 0.02
B2	1.62^b ± 0.03	0.53^a ± 0.04	0.23^a ± 0.02	8.78^a ± 0.63	6.19^c,d ± 0.01	0.47^a ± 0.03	0.08^a ± 0.00
B3	5.03^e ± 0.15	1.06^c ± 0.00	0.57^d ± 0.00	21.73^e ± 0.10	6.51^d,e ± 0.02	1.31^f ± 0.05	0.31^f ± 0.02
B4	2.59^c ± 0.03	1.11^c ± 0.09	0.39^c ± 0.02	18.3^d ± 0.34	13.94^g ± 0.50	0.95^c ± 0.01	0.13^b ± 0.01
B5	1.21^a ± 0.02	0.82^b ± 0.04	0.35^b ± 0.01	9.62^a ± 0.47	3.25^a ± 0.04	0.59^b ± 0.00	0.19^c ± 0.01
B6	4.08^d ± 0.13	1.05^c ± 0.02	0.66^d ± 0.01	15.64^b ± 0.54	4.14^b ± 0.21	0.94^c ± 0.03	0.18^c ± 0.01
B7	4.50^d ± 0.16	1.35^c ± 0.05	0.58^e ± 0.00	16.58^b,c ± 0.43	4.01^a,b ± 0.20	1.05^d ± 0.02	0.30^f ± 0.01
B8	5.04^e ± 0.03	1.13^c ± 0.00	0.55^d ± 0.01	21.93^e ± 0.00	7.07^e,f ± 0.79	1.22^e ± 0.02	0.24^e ± 0.01
B9	2.42^c ± 0.18	1.64^d ± 0.03	0.58^d ± 0.01	17.54^c,e ± 0.37	5.50^c ± 0.13	0.99^c,d ± 0.03	0.21^d ± 0.01
Average	3.84	1.18	0.64	17.33	6.50	1.02	0.21

Mean values from two repetitions ± standard deviations.

Means in the same column with different superscript letters are significantly different (α = 0.05).

Figure 4. Chromatogram of dark beer Erdinger Weissbier after hydrolysis, at 340 nm.

Figure 5. Principal component analysis with distribution of analyzed parameters for the nonhydrolyzed beer samples: CAF: caffeic acid; COU: p-coumaric acid; FA: ferulic acid; GAL: gallic acid; KAE: kaempferol; QUE: quercetin; and SYN: synapic acid.

Figure 6. Principal component analysis with distribution of the nonhydrolyzed beer samples.

Figure 7. Principal component analysis with distribution of analyzed parameters for the hydrolyzed beer samples: CAF: caffeic acid; COU: p-coumaric acid; FA: ferulic acid; GAL: gallic acid; KAE: kaempferol; QUE: quercetin; and SYN: synapic acid.

Figure 8. Principal component analysis with distribution of the hydrolyzed beer samples.

Block, G.; Patterson, B.; Subar, A. Fruit, Vegetables, and Cancer Prevention; A Review of the Epidemiological Evidence. Nutritional Cancer 1992, 18, 1–29.

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