Phenolic profiles and antioxidant activities of commercial beers

The phenolic profiles and corresponding antioxidant activities of 34 commercial beers in Chinese markets were evaluated. Results found remarkable variations in total and individual phenolic contents as well as antioxidant activity across beer brands. Gallic and ferulic acids were the dominant phenolic compounds identified in the tested beer samples and both of them accounted for >50% of the total phenolic compounds. Results from Pearson correlation analysis suggested that five antioxidant activity assays positively correlated well (p < 0.01) with each other and showed significant positive correlations (p < 0.05) with (+)-catechin, protocatechuic, and caffeic acids contents. Stepwise linear regression further demonstrated that different phenolic components responsible for beer antioxidant activity were dependent on the method used, and that ferulic acid, syringic acid, (+)-catechin, caffeic acid, protocatechuic acid and (−)-epicatechin together made 55.0–88.1% of contribution to the antioxidant activity of beer.     

Phenolic Profiles and Total Antioxidant Capacity of Marketed Beers in Serbia

The aim of this research was to determine the total phenolic and flavonoid contents as well as to measure antioxidant activity of 24 different commercial beers consumed in Serbia. The major phenolic acids (gallic acid, protocatechuic acid, 4-hydroxybenzoic acid, 2,5-dihydroxybenzoic acid, vanillic acid, caffeic acid, syringic acid, p-coumaric acid, ferulic acid, sinapic acid, salicylic), (+)-catechin, and (-)-epicatechin were also determined by high pressure liquid chromatography method using a photodiode array detector. Gallic acid, ferulic acid, and protocatechuic acid are the most abundant phenolic acids in all samples, followed by (+)-catechin. The total phenolic content was determined using the Folin-Ciocalteu assay. The total flavonoids were measured using spectrophotometrics as the aluminum chloride assay. The results showed that the highest total phenolic and flavonoid contents were established in dark and light beer samples. 2,2-Diphenyl-1-picrylhidrazyl radical scavenging activity, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) radical cation scavenging activity, and ferric reducing/antioxidant power were used to assess the antioxidant potential of beers. These assays, based on different chemical mechanisms, were selected to take into account the wide variety and range of action of antioxidant compounds present in selected beer samples. All beers showed antioxidant power, but a wide range of antioxidant capacities was observed. Statistical differences between ferric reducing-antioxidant power and the other two antioxidant capacity assays were confirmed. This study will be useful for the appraisal of phenolic profile and antioxidant activities of various beers, and it will also be of interest for people who like drinking this beverage.     

Characterization of Brazilian lager and brown ale beers based on color, phenolic compounds, and antioxidant activity using chemometrics

BACKGROUND: Epidemiological studies have shown that beer has positive effects on inhibiting atherosclerosis, decreasing the content of serum low‐density lipoprotein cholesterol and triglycerides, by acting as in vivo free radical scavenger. In this research, the antioxidant activity of commercial Brazilian beers (n = 29) was determined by the oxygen radical absorbance capacity (ORAC) and 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH^·) assays and results were analyzed by chemometrics. RESULTS: The brown ale samples (n = 11) presented higher (P < 0.05) flavonoids (124.01 mg L^?1), total phenolics (362.22 mg L^?1), non‐flavonoid phenolics (238.21 mg L^?1), lightness (69.48), redness (35.75), yellowness (55.71), color intensity (66.86), hue angle (59.14), color saturation (0.9620), DPPH^· values (30.96% inhibition), and ORAC values (3, 659.36 µmol Trolox equivalents L^?1), compared to lager samples (n = 18). Brown ale beers presented higher antioxidant properties (P < 0.05) measured by ORAC (1.93 times higher) and DPPH (1.65 times higher) compared to lager beer. ORAC values correlated well with the content of flavonoids (r = 0.47; P = 0.01), total phenolic compounds (r = 0.44; P < 0.01) and DPPH (r = 0.67; P < 0.01). DPPH values also correlated well to the content of flavonoids (r = 0.69; P < 0.01), total phenolic compounds (r = 0.60; P < 0.01), and non‐flavonoid compounds (r = 0.46; P = 0.01). CONCLUSION The results suggest that brown ale beers, and less significantly lager beers, could be sources of bioactive compounds with suitable free radical scavenging properties. Copyright © 2010 Society of Chemical Industry     

Roasting of malt and xanthohumol enrichment in beer

The use of commercial roasted malts increases the content of the hop polyphenol xanthohumol (XN) in beer. This carrier effect is caused by high molecular melanoidins from roasted malt. Three roasting trials with different malts were performed in order to study the development of XN enrichment of wort and beer in laboratory and brewing trials. Different colour measurements, malt and flavour analysis, radical formation and antioxidative activity of selected samples were carried out. Furthermore, sensory tests of beers were conducted. During roasting the XN and isoxanthohumol enrichment in wort and beer rose with the roasting intensity of malt until it reached a maximum. The XN content in wort increased linearly with the colour of wort made from the malt samples. In PVPP-treated worts and in filtered beers, the XN content increased exponentially with the colour. After passing through a maximum, both the colour value and XN content in wort and beer decreased. Interestingly, the colour losses were more intensive than the losses of XN in worts and beers. The development of radical formation and the reducing power was linked during roasting. That means reducing groups of melanoidins are responsible for reducing power and prooxidative properties of malts. These functional groups of melanoidins are involved in the development of XN enrichment properties, because a linear correlation between these parameters was found. In conclusion, the roasting regimes showed potential for the development of special malt for the XN enrichment in beer- or malt-based beverages in late roasting stages. The use of this special malt brings more XN with less coloured malt in beer.     

The influence of unmalted barley on the oxidative stability of wort and beer

The aim of this study was to investigate the influences of unmalted barley on the brewing process and the quality of the resulting beer‐like beverages, with the main focus on the oxidative stability, using traditional beer analyses, GC‐MS for the determination of aging compounds and electron paramagnetic resonance spectroscopy to determine free radical activity. For the investigation, brews with different barley proportions and 75% barley brews with a colour malt addition, to compensate for a lower colour using barley, were produced. In general, it can be said that beers with a proportion of up to 50% barley achieved a comparable or higher extract yield and final attenuation owing to the combined effectiveness of the malt and microbial enzymes. Although all analytical values were within the normal range according to Methodensammlung der Mitteleuropäischen Brautechnischen Analysenkommission (MEBAK), a slight decrease in total polyphenols and free amino nitrogen content was observed. Also in response to higher barley portions, an increase of higher molecular weight proteins and β‐glucan was detected. Barley is not exposed to heat and oxidative stress in the malting plant, which explains the lower values of the thiobarbituric acid index and colour as an indicator of Maillard reaction products in the resulting wort and beer. Additionally, the results demonstrate a slower increase of aging compounds during beer storage with increasing barley proportions. Furthermore, it was observed that higher barley proportions led to a better oxidative stability indicated by a lower radical generation (T₄₅₀‐value) in wort and an increasing beverage antioxidant index/endogenous antioxidative potential (BAX/EAP value) in the final beverage. The case of ‘barley beers’ showed that the positive effect of barley on the oxidative beer stability was greater than the negative effect of the addition of colour malt, to adjust the colour of a 100% malt beer. In sensory comparison with beer produced with 100% malt, the beers brewed with a barley proportion up to 50% showed a slight flavour preference and up to a 75% equivalent evaluation. Copyright © 2012 The Institute of Brewing & Distilling     

Antioxidant activity and typical ageing compounds: their evolutions and relationships during the storage of lager beers

Five commercial lager beers were used to investigate the evolution of antioxidant activity and ageing compounds during storage. The relationships between antioxidant activity and ageing compounds were clarified by principal component analysis (PCA). Results showed that total phenolic content (TPC) and antioxidant activities of beers evaluated by different assays gradually decreased by 16.08–22.71% (average of 18.56%) and 1.99–78.79% (averages of 24.44–70.50%), which was accompanied by 100.50–269.35% (average of 178.77%) and 11.11–57.14% (average of 28.73%) of increases in total ageing compounds and thiobarbituric acid (TBA) value, respectively, during 6 months of storage at 25 °C. Results from PCA elucidated that there were negative correlations between antioxidant activities and ageing compounds of beers during storage, and satisfactory discrimination among beers with different storage time could be achieved on the basis of antioxidant activities and typical ageing compounds selected.     

Formation of 4-vinyl and 4-ethyl derivatives from hydroxycinnamic acids: Occurrence of volatile phenolic flavour compounds in beer and distribution of Pad1-activity among brewing yeasts

This work represents a survey of the occurrence of hydroxycinnamic acids and volatile phenols in a variety of beer styles. The contribution of 4-vinylguaiacol to the overall flavour perception of top-fermented specialty beers was shown. Significant differences in hydroxycinnamic acids (both free and ester-bound) and volatile phenol content between different beers were observed. The variability in volatile phenol content between different beers and beer styles can be explained by the high incidence of Pad1⁺ phenotype and the variability of Pad1 activity observed among top-fermenting brewing yeast strains. The relative importance of thermal versus enzymatic decarboxylation can account for the differences found between bottom and top-fermented beers. Concerning the optimisation of volatile phenol levels in beer, the selection of a suitable brewing yeast strain is the most important means of creating a phenolic taste profile in beer. Given that a considerable amount of hydroxycinnamic acids in beer still occurs in ester-bound form, enhancing the enzymatic release of these phenolic flavour precursors during mashing can greatly enhance the phenolic aroma potential of wort.     

The Role of Malt and Hop Polyphenols in Beer Quality,Flavour and Haze Stability

Pilot‐scale brewing trials of a 12°P pale lager beer were conducted to look at the effect of a modified dose of hop and malt polyphenols on haze, flavour quality, and stability. Results confirmed that malt polyphenols, and particularly hop polyphenols, in the course of wort boiling, improved reducing activity values and the carbonyl content in fresh and stored beers. Hop polyphenols significantly increased reducing activity and decreased the formation of carbonyls (TBA value) in fresh and stored beer. Reduced content of malt polyphenols, combined with the use of hop CO₂ extract, caused an increase in the TBA value in beer. PVPP stabilized beers tended to be lower in reducing activity. Both malt and hop polyphenols affected the intensity of “harsh taste” in fresh beers and a significant influence from PVPP stabilization of beer was not observed. The staling degree of forced‐aged beers depended on the polyphenol content in the brewhouse. Both hop and malt polyphenols had a positive impact on flavour stability. PVPP treatment of beer had a positive effect on the flavour stability of heat‐aged beers. Polyphenols, especially hop polyphenols, slowed down flavour deterioration during the nine month storage period, but the primary effect was seen during the first four months of storage. Storage trials did not show any unambiguous effects for PVPP stabilization on beer flavour stability. Results confirmed the negative impact of malt and hop polyphenols on haze stability, and PVPP stabilization minimized differences in shelf life prediction values between beers prepared with the modified dose of polyphenols.     

Physicochemical characterization of special persimmon fruit beers using bohemian pilsner malt as a base

This study involved the production of special fruit ale beers with different concentrations (100:0%, 75:25%, 50:50% and 25:75% v /v) of barley malt and persimmon juice from the ‘Rojo Brillante’ variety. Fermentation took place under beer quality control parameters and the influence of persimmon juice on beer quality was investigated. Colour, turbidity, pH, titratable acidity, total soluble solids, sugars, organic acids, total phenolic compounds, antioxidant capacity and ethanol formation were determined during the fermentation process. These fruit beers, whose alcoholic contents were within the standards (3.6–5.63% v /v ethanol), were characterized by a normal acid pH (3.97–4.13) with citric and lactic acids the most abundant organic acids, a clear golden colour without turbidity [2.05–2.83 European Brewery Convention units], intermediate total phenolic compound values (283.0–327.1 mg GAE/L) and antioxidant activities between 1.65 and 5.78 mm TE/L. The persimmon beverage which contained 75% fruit juice was the most valued and preferred by the panelists followed by the 50:50% wort–persimmon beer. Copyright © 2017 The Institute of Brewing & Distilling     

Content of Individual Phenolic Acids in Worts and Beers and their Possible Contribution to the Antiradical Activity of Beer

Phenolic acids are widely distributed in foods and raw materials. They are easily absorbed by humans due to their simplicity. Once they enter the blood plasma, they act as antioxidants. Beer can be a rich source of phenolic acids in the diet. The aim of this study was to determine the concentrations of phenolic acids in two experimental worts and beers as well as in nine market beers (using HPLC‐UV). An examination of the total antiradical activities of phenolic acids with in vitro model systems (using ABTS and DPPH free radicals), at the concentrations comparable to those detected in beers, was performed. Only low fractions of the main phenolic acids present in barley malt (ferulic, vanillic and p‐coumaric acid) were detected in the experimental worts. Moreover, the concentrations of phenolic acids significantly decreased until the last steps of beer production. The main beer phenolic acids (vanillic and ferulic acid) exerted a lower share of total antiradical activity against both free radicals (calculated as the sum of the individual activities of all acids detected in beer) than the minor phenolic acids (caffeic, chlorogenic, o‐coumaric, sinapic or syringic acid). The synergies, between individual phenolic acids in pairs, were also studied with in vitro model solutions using free radicals. The total antiradical activity of the compounds studied in pairs, was at the most as high as the sum of the antiradical activity of the individual phenolic acids, but in most cases it was considerably lower (i.e. no synergy was detected).     

THE OCCURRENCE OF TWO GEOMETRICAL ISOMERS OF 2,4,5-TRIMETHYL-1,3-DIOXOLANE IN BEER

Two geometrical isomers of 2,4,5-trimethyl-1,3-dioxolane have been detected in a range of commercial and experimental beers at levels up to ca 0.1 ppm. These compounds, plus a number of other dioxolanes, are present in unboiled wort but are lost by evaporation during wort boiling. The trimethyldioxolanes are then reformed during subsequent fermentation. The flavour threshold of a mixture of the two trimethyldioxolanes was found to be ca 0.9 ppm, at which concentration it produced in beer ‘phenolic’ and ‘astringent/drying’ flavour notes. However, these compounds are not present in sufficiently high concentrations to make a significant contribution to the flavour of beer.     

The Influence of Hopping on Formation of Carbonyl Compounds During Storage of Beer

Improving beer flavour stability is an important brewing goal. Pilot scale brewing trials (50 L) were performed that focused on the determination of the influence of hop pellet dosage and dosage timing on carbonyl compounds in stored beer. The reducing activity of experimental worts, beers and stored beers appeared to depend on the hop pellet dose. Brews with lower amounts of hop antioxidants showed an enhanced formation of carbonyl compounds over the course of beer storage. A correlation between DPPH reducing activity and the content of some carbonyls, including the important markers 2‐furfural and (E)‐2‐nonenal, was found. Fresh and aged beers hopped by different amounts of hop pellet doses were clearly distinguishable according to their carbonyl content using Cluster analysis. Results of the sensorial analysis corresponded to the analytical criteria values. Results of this study bring further evidence of the indispensable impact of hop antioxidants on the suppression of undesirable carbonyl compound formation in the course of beer staling, which can be significant in beers hopped by aroma hops. However, hop antioxidants are only one of many factors affecting beer staling.     

热泵干燥过程荔枝果肉多酚组成及抗氧化活性变化

以荔枝鲜果为原料,分析高温热泵干燥过程中荔枝果肉多酚的组成及抗氧化性活性变化。对干制过程中荔枝进行取样测定果肉总酚的质量分数、存在形式及酚类化合物组成和其抗氧化能力。结果表明:荔枝经干制后果肉中游离酚、结合酚和总酚质量分数显著降低(P<0.01);游离酚、结合酚和总酚的ORAC抗氧化值显著降低(P<0.01),其中游离酚对抗氧化能力的贡献最大;抗氧化能力和酚质量分数的多少呈显著正相关,酚质量分数越高,抗氧化能力越强。经干制后,荔枝果肉游离酚组成中没食子酸、香草酸、咖啡酸、表儿茶素和芦丁质量分数显著上升(P<0.05);儿茶素显著下降(P<0.05);四甲基邻苯二酚质量分数持续下降,干制成品中未检测到;结合酚中没食子酸、儿茶素、咖啡酸和表儿茶素质量分数显著上升(P<0.05);芦丁质量分数显著下降。     

Predicting the organoleptic stability of beer from chemical data using multivariate analysis

Delaying flavour staling, to prolong the shelf life of beer, is one of the greatest challenges facing the brewing industry today. In this study, a series of lager beers were brewed using five European barley varieties and four chemical indicators of the degree of beer ageing were correlated with the sensory evaluation: E-2-nonenal, β-damascenone, 2-furaldehyde and 5-hydroxymethyl-2-furaldehyde (5-HMF). A statistical strategy using principal component analysis and multiple linear regression was applied to draw relationships between the sensory and chemical data sets. Additionally, the relative significance of each of the chemical data on the organoleptic stability of beer was evaluated within the method. 5-HMF was the only studied carbonyl compound whose concentration cannot be used for predicting the total taste score of beers. E-2-nonenal, in contrast, was found to be the most discriminant carbonyl compound under consideration for predicting the flavour stability of beer.     

Volatile compounds isolated from rice beers brewed with three medicinal plants

The volatile compounds and physicochemical properties of rice beers brewed with three medicinal plants, namely Acanthopanax senticosus (Siberian ginseng), Scutellaria baicalensis (baikal skullcap) and Cornus officinalis (Japanese cornel) were analysed. The rice beers were produced and fermented from unhulled ground rice, malt, and medicinal plant extracts. The medicinal plant extracts, used at 5 and 10 % (v/v) were blended with wort before fermentation. Compared with a draft beer fermented without rice, the rice beers had lower levels of pH, acidity, amino acid content and reducing sugars. Of the rice beers, the beer with the addition of 10% Japanese cornel had the highest colour value and foam stability. The volatile compounds of the rice beers were extracted using a solvent‐assisted flavour evaporation apparatus and analysed by gas chromatography–mass spectrometry. The rice beer with 10% Siberian ginseng showed the most diverse volatile profile, in that 54 kinds of volatile compounds were detected. The rice beer with 10% Japanese cornel had the highest relative amount of volatile chemicals of all of the rice beers. Lactones such as γ‐hexalactone, γ‐nonalactone and γ‐decalactone were detected in all of the rice beers. Copyright © 2013 The Institute of Brewing & Distilling     

绿茶、橘皮、大豆中酚类物质体外消化前后稳定性及抗氧化活性的研究

本研究以富含3类代表性酚类化合物（黄烷醇、黄烷酮和异黄酮）的3种食物（绿茶、橘皮、大豆）作为原料,模拟其在人体口胃肠中的体外消化过程。采用高效液相色谱-二极管阵列检测器/电喷雾-四极杆-飞行时间串联质谱检测器（HPLC-DAD/ESI-Q-TOF-MS）检测体外消化前后酚类化合物的种类及含量变化,同时测定不同消化阶段总酚含量（TPC）、总黄酮含量（TFC）以及抗氧化活性（DPPH、ABTS、FRAP、ORAC）的变化。结果表明,绿茶提取物中检测出4种酚类化合物（表没食子儿茶素、(+)-儿茶素、表没食子儿茶素没食子酸酯和表儿茶素没食子酸酯）,大豆提取物中检测出4种酚类化合物（大豆苷、染料木苷、大豆苷元和染料木素）,橘皮提取物中检测出2种酚类化合物（柚皮苷和橙皮苷）;三种食物提取物中,经过体外消化后,绿茶提取物中的酚类化合物最不稳定,除(+)-儿茶素外,其余3种酚类物质几乎降解完全,损失率均达95%以上。绿茶、橘皮、大豆提取物的TPC在胃消化阶段显著升高（P<0.05）,在肠消化阶段显著降低（P<0.05）。绿茶提取物TFC在口腔和胃消化阶段显著升高（P<0.05）,在肠消化阶段显著降低（P<0.05）。橘皮、大豆提取物TFC与TPC变化趋势一致。绿茶提取物的四种抗氧化活性经胃肠消化后呈先升高再降低的趋势。大豆提取液体外消化前后ABTS、FRAP抗氧化活性在口腔阶段显著降低（P<0.05）,DPPH、ORAC抗氧化活性在口腔、胃消化阶段显著升高（P<0.05）,在肠消化阶段显著降低（P<0.05）。橘皮提取液ORAC抗氧化活性在肠消化阶段显著升高（P<0.05）,ABTS、FRAP抗氧化活性在体外消化阶段均表现出和总酚含量变化一致的趋势。     

Effect of wine barrel ageing or sapa addition on total polyphenol content and antioxidant activities of some Italian craft beers

Beer is a complex mixture of bioactive polyphenols with positive health effects, and its composition is influenced by some technological variables. In this study, the total polyphenol content (TPC) and the antioxidant activity of some Italian craft beers produced by ageing in wood barrel that previously contained red or white wines, and by addition of sapa, a cooked must from wine grapes, were investigated. TPC greatly vary among different beer types. Craft beers stored in wood barrels that contained red wines, such as those added of sapa from red wine grapes, showed a TPC up to 2.5 times higher (1000 GAE mg L^?1) compared with other craft beers, and 3.6 times higher than the industrial beer. The antioxidant activity is remarkably different depending on beer type and strictly correlated with TPC. Results indicate that antioxidant properties of the craft beers could be efficiently improved by the explored technological processes.     

Kinetic changes of polyphenols,anthocyanins and antioxidant capacity in forced aged hibiscus ale beer

Three craft ale beers contained 5, 10 and 20 g/L Hibiscus sabdariffa L. aqueous powered extract (HS) were submitted to a forced aging process for 7 days at 45°C, and the changes with time of physicochemical parameters, anthocyanins, total phenolic compounds (TPC) and antioxidant activities (AOX) were monitored. The determination of the individual characteristics of the 20 g/L HS beer after forced aging indicates that it was characterized by low pH and browning index, slight red hue, and high TPC content and AOX. It becomes clear that HS extract had a noticeable effect on the acidity and colour of beer and it was an important source of phenolics and anthocyanins, compounds with AOX. When the evolutions of the general parameters were compared, hibiscus beer showed the weakest tendency to age, giving as result lesser red colour loss and AOX owing to a low anthocyanin degradation and brown pigment formation. Copyright © 2017 The Institute of Brewing & Distilling     

Relationship between the chemical composition and the biological activities of food melanoidins

The relationship between the chemical composition and the biological activities of food melanoidin-rich fractions was investigated. Melanoidin-rich fractions were extracted using ultrafiltration (a 10 kDa cut-off) from coffee, barley coffee, dark beer, and traditional balsamic vinegar. All the food melanoidin-rich fractions were formed mainly of carbohydrates, phenolic compounds, and proteins. In dark beer, barley coffee, and traditional balsamic vinegar melanoidins, glucose was the most abundant sugar incorporated into melanoidins. Coffee melanoidins contained the largest amount of phenolic groups, followed by traditional balsamic vinegar melanoidins. The radical scavenging, Fe²⁺-chelating, and heme binding abilities of food melanoidins were investigated under gastric conditions. The melanoidinrich fraction extracted from coffee was the most active, showing the highest radical scavenging, Fe²⁺-chelating, and heme binding activities, compared to barley coffee, dark beer, and traditional balsamic vinegar. The radical scavenging and Fe²⁺-chelating abilities were assigned to the phenolic groups present in food melanoidins.