An Attempt to Identify the Low Molecular Feruloylated Oligosaccharides in Beer

Ferulic acid (4‐hydroxy‐3‐methoxycinnamic acid), predominantly in ester form in arabinoxylan chains, is the main phenolic acid present in barley and malt. Only about 1% of the total ferulic acid in barley is present in the free form. A number of previous works concerned the contents of free and esterified ferulic acid in a broad range of popular beers, but there is little information about the possible composition of feruloylated oligosaccharides in beers. The aim of this preliminary work was to purify the feruloylated oligosaccharides from lager beers (by the means of preparative chromatography) followed by composition elucidation using TLC, HPLC with RI or UV detection and ¹H‐NMR. Indeed, the qualitative analyses of isolated fractions from beer revealed that the fractions contained ferulic acid in the ester form (as proven after mild alkaline hydrolysis). It was also shown that molecular masses of oligosaccharides present in the purified beer fractions were similar to the masses of arabinose and xylooligosaccharides in the range of xylose to xylohexaose. Although a number of purified beer samples contained oligosaccharides of higher molecular masses, these were not further characterized. Taking under consideration the presented results, it can be concluded that beer can be a good source of feruloylated oligosaccharides, significant in the context of human health benefits.     

草酸蒸煮处理和表面活性剂对酶法制备低聚糖阿魏酸酯的影响

低聚糖阿魏酸酯兼具低聚糖的益生菌增殖活性和阿魏酸的抗氧化活性,可通过水解阿拉伯木聚糖获得。本文采用阿魏酸含量最高的玉米皮为原料,研究草酸蒸煮处理和添加表面活性剂对酶解玉米皮制备低聚糖阿魏酸酯的影响。研究结果显示:草酸含量0.6%,料液比1:10(W:V),0.1MPa蒸煮20min后,采用木聚糖酶酶解可获得阿魏酸含量为14.10mg/g的低聚糖阿魏酸酯,并将玉米皮中52.2%的阿魏酸游离出来。酶解过程中,添加表面活性剂Tween-80、Tween-20和Span-80,能显著提高玉米皮的酶解效率。当3者添加量分别为4%、3%和2%时,低聚糖阿魏酸酯中阿魏酸含量分别提高到190%、128%和152%。使用Span-20可降低阿魏酸酯产量。     

CONTROL OF FERULIC ACID AND 4-VINYL GUAIACOL IN BREWING

Phenolic acids in beer are important because they can be decarboxylated to phenols, which usually impart off-flavours. An improved high performance liquid chromatographic system was used to monitor phenolic acids and phenols during the brewing process. Ferulic acid was the most significant phenolic acid found in beers prepared from malted barley. Extraction of ferulic acid from malt involved an enzymatic release mechanism with an optimum temperature about 45°C. Mashing-in at 65°C significantly decreased the release of free ferulic acid into the wort. Wort boiling produced 4-vinyl guaiacol by thermal decarboxylation, in amounts (0.3 mg/L) close to its taste threshold, from worts that contained high contents of free ferulic acid (> 6 mg/L). The capacity of yeasts to decarboxylate phenolic acids (Pof⁺ phenotype) was strong in wild strains of Saccharomyces and absent in all lager brewing yeast and most ale brewing yeasts. Some top-fermenting strains, especially those used in wheat beer production, possessed a weak decarboxylating activity (i.e. Pof^δ). During storage of beers there were appreciable temperature-dependent losses of 4-vinyl guaiacol. These results indicated that the production of 4-vinyl guaiacol is amenable to close technological control.     

对香豆酸、阿魏酸和低聚糖阿魏酸酯对酪氨酸酶的抑制效果

通过测定酶的稳态活力、迟滞时间和动力学参数,研究对香豆酸、阿魏酸及低聚糖阿魏酸酯对酪氨酸酶的抑制效果。结果表明,3种物质对酪氨酸酶单酚酶活性均有抑制作用,其中对香豆酸的抑制作用最强,其次为低聚糖阿魏酸酯和阿魏酸。对香豆酸、低聚糖阿魏酸酯和阿魏酸对单酚酶的IC_(50)值分别为0.75,3.20,9.30 mmol/L。对香豆酸和阿魏酸抑制二酚酶活性,IC_(50)值分别为4.3,12.7mmol/L;但低聚糖阿魏酸酯对二酚酶活力没有影响。对香豆酸能明显延长单酚酶反应的迟滞时间,阿魏酸影响很小,而低聚糖阿魏酸酯则缩短迟滞时间。动力学研究结果显示,阿魏酸和低聚糖阿魏酸酯对单酚酶的抑制作用表现为混合性抑制,而对香豆酸为竞争性抑制。     

Antioxidant activity of feruloylated oligosaccharides from wheat bran

Ferulic acid, the main phenolic acid in wheat bran, is esterified to arabinose residues in the cell wall arabinoxylan. Treatment of wheat bran insoluble dietary fibre with xylanases from Bacillus subtilis released feruloylated oligosaccharides, which were purified with Amberlite XAD-2. The antioxidant activity of such oligosaccharides was evaluated using the assay system for erythrocyte hemolysis mediated by peroxyl free radicals generated from 2,2^′-azobis-2-amidinopropane dihydrochloride (AAPH) under in vitro conditions. The feruloylated oligosaccharides inhibited hemolysis of erythrocytes in a dose-dependent manner with 91.7% inhibition of erythrocyte hemolysis at 4 mg/ml.     

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).     

酶法制备黑小麦麸皮阿魏酰低聚木糖的工艺优化

研究黑小麦麸皮阿魏酰低聚木糖(FOs)的酶法制备工艺。用木聚糖酶酶解水不溶性膳食纤维制备FOs,通过HPLC分析方法,并结合双波长法和薄层层析法对FOs的含量和组成进行分析。在加酶量、反应时间、p H、温度4个单因素实验基础上,采用四因素三水平的中心旋转设计,以FOs浓度为响应值,使用响应面分析法对FOs的制备工艺进行优化,得到最佳工艺参数为:加酶量15.5 mg/L,酶解时间22 h,温度46℃,p H4.8,在此条件下,FOs的浓度为0.4913 mmol/L。薄层层析和HPLC分析结果表明,酶解液中的低聚糖含有结合态阿魏酸,是阿魏酰低聚木糖。      

Association of non-starch polysaccharides and ferulic acid in grain amaranth (Amaranthus caudatus L.) dietary fiber

The association of ferulic acid, an alkali-extractable phenolic acid in amaranth (Amaranthus caudatus L., Amaranthaceae) insoluble fiber (trans-ferulic acid: 620 microg.g-1, cis-ferulic acid: 203 microg.g-1), and non-starch polysaccharides was investigated. Enzymatic hydrolysis of insoluble amaranth fiber released several feruloylated oligosaccharides that were separated using Sephadex LH-20-chromatography and reversed phase-high performance liquid chromatography (RP-HPLC). Three compounds were unambiguously identified: O-(6-O-trans-feruloyl-beta-D-galactopyranosyl)-(1-->4)-D-galactopyranose, O-(2-O-trans-feruloyl-alpha-L-arabinofuranosyl)-(1-->5)-L-arabinofuranose, and O-alpha-L-arabinofuranosyl-(1-->3)-O-(2-O-trans-feruloyl-alpha-L-arabinofuranosyl)-(1-->5)-L-arabinofuranose. These feruloylated oligosaccharides show that ferulic acid is predominantly bound to pectic arabinans and galactans in amaranth insoluble fiber. 5-O-trans-Feruloyl-L-arabinofuranose was the only compound isolated in pure form from an acid hydrolyzate. This compound may have its origin from pectic arabinans but also from arabinoxylans.     

PHENOLIC ACIDS IN BEERS AND WORTS

The total contents of phenolic acids measured by high-performance liquid-chromatography were 5–8 mg/litre in beers brewed in Ireland whereas 16–40 mg/litre were present in four other beers. In all beers the predominant phenolic acids were vanillic, p-coumaric and ferulic acids. Free phenolic acids were extracted from Emma barley grains and malt in very small amounts (15–28 mg/kg) but larger quantities (191 mg/kg) were released on mashing the malt. Little change occurred in the contents of phenolic acids on processing a lager wort through to the finished beer. Treatment with excess Polyclar AT removed astringent flavour and phenolic acids from an experimental ale but this flavour loss could not be accounted for by the adsorption of phenolic acids. The flavour threshold for a nine-component phenolic acid mixture in lager was between 50 mg/litre and 100 mg/litre.     

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.     

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.     

Release of phenolic flavour precursors during wort production: Influence of process parameters and grist composition on ferulic acid release during brewing

In this study, the effects of mashing variables such as mashing-in temperature, time and pH, mash thickness, grist coarseness and composition, and stirring regime on the release of ferulic acid were examined. Ferulic acid is a precursor for the formation of flavour-active volatile phenols and a potent natural antioxidant in beer. Given one barley malt variety, the multitude of choice in setting various process parameters and adding brewery adjuncts during brewhouse operations can give rise to worts with widely varying ferulic acid levels. A clear difference in temperature- and pH-dependence between the release of the water-extracted and the enzymatically hydrolyzed fraction was found. The T,t-dependencies of arabinoxylan-degrading enzyme activities were correlated with ferulic acid release during mashing. Results from laboratory-scale mashing experiments were validated with those from a pilot-scale (5 h) wort production process. Enhancing the enzymatic release of phenolic flavour precursors from bound forms during mashing can greatly enhance the phenolic aroma potential of wort. Optimising this precursor release during mashing may be a means for controlling final volatile phenol levels in beer.     

ESTIMATION OF ALGINATE,CARRAGEENAN AND FURCELLARAN IN BEER

Quantitative and semi-quantitative methods are given for estimating alginate, carrageenan and furcellaran at low concentrations in beer. A number of commercial beers and experimental beers known to have been brewed with either copper finings or auxiliary finings containing these acidic polysaccharides as active ingredients were analysed for alginate, carrageenan and furcellaran residues. The results show that alginate and carrageenan do not occur in finished beers at levels greater than 1 mg/litre. Using a serological technique which is more sensitive for furcellaran, it was found that levels of furcellaran in most finished beers were below 0.5 mg/litre, though a few beers contained this polysaccharide at about 0.5 mg/litre.     

比利时/德国小麦啤酒风味物质差异研究

以大麦芽、小麦芽和未发芽的小麦为原料,添加酒花、橘皮和芫荽籽,使用上面发酵酵母No.303,酿造比利时风格和德国风格小麦啤酒。该研究介绍了两种风格小麦啤酒的酿造工艺,对两种风格的成品小麦啤酒进行风味物质检测分析以及感官品评,探讨了比利时风格小麦啤酒和德国风格小麦啤酒风味物质的差异。结果表明,比利时风格小麦啤酒乙醛含量更为适宜（约为2.6 mg/L）,高级醇和乙酸含量较高（分别为113 mg/L和160 mg/L）,酯类物质含量偏低（约为50 mg/L）,成品啤酒橘香味突出,但酯香味不够充足;德国风格小麦啤酒乙醛和酯类物质含量略高（分别为3 mg/L和63 mg/L）,高级醇含量稍低（约为104 mg/L）,乙酸含量适宜（约为135 mg/L）。     

甘蔗不同组织中游离态和结合态酚酸的分布及抗氧化活性

为了探讨甘蔗不同组织中酚酸的存在形式,本文利用反相高效液相色谱法(RP-HPLC)对蔗汁、蔗叶及蔗渣三个组织中游离态和结合态的酚酸进行了定性和定量检测分析。结果表明,甘蔗组织中的酚酸主要以结合态形式存在,但其在甘蔗三个组织中的含量和存在形式有差别。甘蔗叶、蔗渣中游离的酚酸含量最高,蔗汁较低。蔗汁、蔗叶及蔗渣中总游离态酚酸含量分别为317.18 mg/kg(干固物),1568.37 mg/kg(干基)及1504.57 mg/kg(干基);总结合态酚酸含量分别为740.32 mg/kg(干固物),2725.41 mg/kg(干基),2452.13 mg/kg(干基)。在蔗汁中,咖啡酸、没食子酸主要以游离态存在,阿魏酸、香豆酸主要以结合态存在,而在蔗叶和蔗渣中,咖啡酸、阿魏酸、香豆酸主要以结合态形式存在。甘蔗不同组织中游离态酚酸的DPPH和ABTS自由基清除活性优于结合态酚酸,不同组织中的游离态酚酸和结合态酚酸含量分别与抗氧化活性呈正相关性。     

Ferulic acid: pharmaceutical functions,preparation and applications in foods

Ferulic acid (4‐hydroxy‐3‐methoxycinnamic acid), an effective component of Chinese medicine herbs such as Angelica sinensis, Cimicifuga heracleifolia and Lignsticum chuangxiong, is a ubiquitous phenolic acid in the plant kingdom. It is mainly conjugated with mono‐ and oligosaccharides, polyamines, lipids and polysaccharides and seldom occurs in a free state in plants. Ferulic acid is a phenolic acid of low toxicity; it can be absorbed and easily metabolized in the human body. Ferulic acid has been reported to have many physiological functions, including antioxidant, antimicrobial, anti‐inflammatory, anti‐thrombosis, and anti‐cancer activities. It also protects against coronary disease, lowers cholesterol and increases sperm viability. Because of these properties and its low toxicity, ferulic acid is now widely used in the food and cosmetic industries. It is used as the raw material for the production of vanillin and preservatives, as a cross‐linking agent for the preparation of food gels and edible films, and as an ingredient in sports foods and skin protection agents. Ferulic acid can be prepared by chemical synthesis and through biological transformation. As polysaccharide ferulate is a natural and abundant source of ferulic acid, preparation of ferulic acid from plant cell wall materials will be a prospective pathway. Copyright © 2004 Society of Chemical Industry     

玉米芯功能性低聚糖分级纯化及抗氧化活性研究

探究玉米芯功能性低聚糖分级纯化前后不同组分的组成、理化性质和抗氧化活性。以玉米芯为原料,采用活性炭柱层析法对玉米芯功能性低聚糖进行分级纯化,对纯化前后组分的聚合度、相对分子质量、阿魏酸基团以及红外光谱特性进行分析,并对酶解低聚糖粗提物(EH)及其纯化组分的自由基清除能力和抑制脂质过氧化能力进行比较分析。结果表明：活性炭水洗脱低聚糖组分(WO)、醇洗脱低聚糖组分(EO)均主要由木糖和阿拉伯糖组成,其中WO含有结合态阿魏酸,为阿魏酰阿拉伯低聚木糖;EO不含结合态阿魏酸,为阿拉伯低聚木糖。EH及其纯化组分WO、EO均具有一定的清除自由基(DPPH·、·OH、ABTS⁺·)能力和抑制脂质过氧化能力,且随浓度的增加而增加,WO抗氧化活性最强,EH次之,EO抗氧化活性较弱。     

Extraction of ferulic acid from sugar beet pulp by alkaline hydrolysis and organic solvent methods

Extraction of ferulic acid from sugar beet pulp was carried out using three extraction solvents, sodium hydroxide (0.5, 1, 2 M), methanol and their mixture (alkaline methanolic solvent). The Ferulic acid extracted by each solvent was identified and quantified by HPLC method and the effects of solvent type, concentration and reaction time on ferulic acid solubilisation were assessed. There were differences in the contents of products extracted in the experiment conditions. The minimum amount of ferulic acid was obtained from methanolic extract while the highest concentrations (957.4 mg/L ferulic acid) were obtained employing the highest NaOH concentration (2 M), and reaction time (12 h), so phenolic compounds are better released with alkaline hydrolysis than in methanol conditions. Finally a simple procedure for the purification of ferulic acid from the alkaline extracts is presented and evaluated by FT-IR spectrum.     

Corn grist adjunct – application and influence on the brewing process and beer quality

In the brewing industry, barley malt is often partially replaced with adjuncts (unmalted barley, wheat, rice, sorghum and corn in different forms). It is crucial, however, to preserve constant quality in the beer to meet the expectations of consumers. In this work, how the addition of corn grist (10 and 20%) influences the quality of wort and beer was examined. The following parameters were analysed: wort colour, dimethyl sulphide (DMS) and protein content, non‐fermentable extract, extract drop during fermentation, alcohol content and the attenuation level of the beer, together with filtration performance. The samples (all‐malt, and adjunct at 10 and 20% corn grist) were industrial worts and the beers produced in a commercial brewery (3000 hL fermentation tanks). The application of 10 and 20% corn grist had an effect on the wort colour, making it slightly lighter (11.1 and 10.5°EBC, respectively) than the reference barley malt wort (12.2°EBC). The free amino nitrogen level, DMS and non‐fermentable extract were significantly lower in the worts produced with the adjunct; the alcohol content and attenuation levels were higher in the beers produced with adjunct. The use of corn grist, at the level of up to 20% of total load, appears to affect some of the technological aspects of wort and beer production, but it does not significantly influence the final product characteristics. Copyright © 2014 The Institute of Brewing & Distilling     

Hydrolysis of Brewers' Spent Grain by Carbohydrate Degrading Enzymes

In this work four commercial cellulase‐hemicellulase mixtures with different activity profiles were used for solubilization of carbohydrates from brewers' spent grain (BSG). After the enzyme treatment, both the solubilised fraction and the unhydrolysed residue were characterized. Treatment with 5,000 nkat/g xylanase for 5 h at 50°C resulted in the solubilisation of 13–14% of the BSG dry weight as monosaccharides. This corresponded to the solubilisation of 26–28% of the original carbohydrates and 30–34% of original arabinoxylans, depending on the enzyme cocktail used. The relatively low hydrolysis level indicates that the majority of the BSG biomass is rather recalcitrant towards the cellulose‐hemicellulase enzyme mixtures applied in this study. The enzyme activity profile had a crucial impact on the chemistry of the oligosaccharides produced through the solubilisation of BSG. The presence of feruloyl esterase (FAE) activity in the enzyme cocktail resulted in the production of free ferulic acid, arabinoxylo‐oligosaccharides and their corresponding monomers. However, when the enzyme mixture was devoid of FAE activity, ferulic acid was still bound to the oligosaccharides. The unhydrolysed fraction was still found to contain over 40% of carbohydrates after enzymatic treatment despite the extensive enzyme dosages used. The protein fraction remained largely unaffected (i.e. insoluble) by the carbohydrate‐disrupting enzyme treatments. In addition to the recalcitrant carbohydrates, the residue was enriched with lignin and lipid type structures.