磨木木素在硫酸盐法蒸煮过程中的反应

在木糖存在的条件下,采用硫酸盐法蒸煮的方法对蓝花楹磨木木素(milled wood lignin,简称MWL)进行处理,然后对处理后的产物进行红外光谱和13C-NMR分析,研究蓝花楹MWL的结构变化,探讨在硫酸盐法蒸煮过程中木素-碳水化合物复合体(lignin-carbohydrate complexes,简称LCC)的形成情况。研究发现:蓝花楹MWL结构单元之间的α-烷基芳基醚键、β-O-4型连接键很容易发生断裂,而在这些连接键发生断裂的同时,形成的木素中间体与糖产生化学键的结合,蒸煮液中有新的LCC结构形成。     

COMPARISON OF SCOTCH MALT WHISKY MATURATION IN OAK MINIATURE CASKS AND AMERICAN STANDARD BARRELS

The sensory and chemical attributes of Scotch malt distillate matured in uncharred, American white oak casks, were compared with distillate matured in miniature casks of similar wood with a capacity of 6 Litres. The maturation profiles of the two types of casks differed in the pattern of extraction of wood components and in the flavour characteristics of the final distillates. The product from the miniature cask maturations was not comparable with a Scotch malt whisky, due to differences in the ratios of concentrations of extractives. This may relate to differences in oxidation rates in the two cask types.     

Changes in wood extractives from oak cask staves through maturation of scotch malt whisky

Cask staves, prepared from American white oak, Quercus alba, were obtained from unused, new charred Bourbon, used Bourbon, first-fill Scotch and exhausted Scotch casks. The aim of the experiment was to determine the effect of repeated maturations of whisky on concentration and location of phenolic extractives in the cask wood. Contents of vanillic and syringic acids and the respective aldehydes, arising from hydrolysis of guaiacyl-syringyl lignin, and whisky lactones (cis- and trans-β-methyl-γ-octalactone), arising from charring, were determined. Staves were sampled at 5 mm intervals from the inner char surface to 25 mm depth and wood extracted with chloroform, heptane and aqueous ethanol. Contents of material absorbing at 520 nm, total phenols and vanillic and syringic acids, vanillin and syringaldehyde, were determined by high-performance liquid chromatography; both isomers of whisky lactone were quantified by high-resolution gas chromatography. New cask wood had a maximum for coloured material in the char layer, but maxima for other compounds at 5 mm below the char. As casks were reused in maturations of whiskies, the contents of aromatic aldehydes and acids were reduced in the first 20 mm of the wood and maxima for both acids and aldehydes shifted towards the centre of the staves. This suggested that repeated exposure to aqueous ethanol resulted in compositional changes in the lignin in the wood. The newly charred wood had a maximum for cis-β-methyl-γ-octalactone at 5 mm below the char and the trans isomer at 15 mm. In the first Bourbon maturation both isomers were largely depleted and with successive extractions the maxima moved into the cask until in the exhausted cask wood no lactone was detected.     

Role of Organic Acids in Maturation of Distilled Spirits in Oak Casks

Maturation of whiskies and brandies in oak casks proceeds by reducing the perception of less desirable aromas of new distillates. During maturation, extraction of wood components increases the solubility of distillate compounds which reduces their headspace concentration above the matured spirit. The origins of this interaction are changes in aggregation of ethanol due to increases in contents of organic acids. During wood maturation organic acid concentrations in spirits increase as a result of extraction from cask wood, oxidation of ethanol and evaporation of ethanol and water. The effect of such changes was simulated using a model whisky ester in aqueous solutions of ethanol with acetic acid, oak wood extracts and acid fractions from new and matured Scotch malt distillates.     

Heartwood dry extract: a key fraction for the quality and the diversity of rums and spirits

Oak heartwood provides easily soluble dry extract. The fraction is rich in various polymers including polysaccharides, polyphenols and lignin. During cask ageing, spirit composition improves by the addition of oak dry extract. New spirits, such as white rums, develop colour and character such as softness and sweetness. Mouthfeel and presentation of the final product are completely changed. The content of alcohol and dry extract influence the thickness and taste of the spirit. Microviscosity was measured in a commercial rums and other spirits, highlighting a direct correlation between dry extract and microviscosity. Two indices are proposed for the evaluation of ageing in oak casks: the ratio of Total Polyphenols Index (TPI)/dry extract and the Global Tastefully Index integrating microviscosity and TPI. The proposed indices allowed the differentiation between (i) long aged products, (ii) short ageing and (iii) white spirits with short ageing and artificial treatments mimicking cask ageing. © 2020 The Institute of Brewing & Distilling     

烟草木质素结构的二维核磁共振波谱表征

[背景和目的]烟草木质素对烟草品质和安全性有重要影响,为了提高烟草制品的质量,需要探究烟草木质素的化学结构及含量.[方法]利用二维异核单量子相干核磁共振技术(2D HSQC NMR)建立表征烟草木质素的方法,实现烟草木质素的结构表征及半定量分析.[结果](1)烟草样品木质素中共发现10种主要的木质素基本单元及单元间连接...     

Fractionation and characterization of ball‐milled and enzyme lignins from abaca fibre

An Erratum has been published for this article in Journal of the Science of Food and Agriculture 79(15) 1999, 2122. Ball‐milled and enzyme lignins were produced from abaca fibre via ball milling for 6 days followed by cellulase treatment for 3 days. The crude lignin preparations were fractionated into milled lignin (ML), enzyme lignin (EL), hemicellulose‐rich milled lignin (HRML), and lignin‐rich enzyme lignin (LREL) fractions using a two‐step precipitation method instead of a traditional ether precipitation procedure. The yield and chemical composition of the resulting lignin samples are reported. The ML and EL fractions contained low amounts of associated neutral sugars (2.0–3.3%) and uronic acids (1.4–1.5%), and showed relatively low average molecular weights (2500–2660), while the LREL and HRML fractions contained large amounts of bound polysaccharides (35.6–38.3%), and showed high molecular weights (8800–25000). The four lignin fractions are composed of a large proportion of syringyl units with fewer guaiacyl and p‐hydroxyphenyl units. The ML is mainly composed of β–O–4 ether bonds between the lignin structural units. The less common β–β, β–5 and 5–5′ carbon–carbon linkages are also present in the lignin molecules. It was found that uronic acids and 41–63% of p‐coumaric acids are esterified to lignin in the three lignin‐rich fractions of ML, EL and LREL. This level increased to over 90% in the hemicellulose‐rich fraction of HRML. For ferulic acids, 92–97% were found to be etherified to lignin in the three lignin‐rich fractions of ML, EL and LREL, while in the hemicellulose‐rich fraction of HRML this reduced to only 13%, suggesting that a majority of the ferulic acids are esterified to hemicelluloses or lignin in this fraction. © 1999 Society of Chemical Industry     

Determination of Total Charge Content of Whiskey by Polyelectrolyte Titration: Alteration of Polyphenols

ABSTRACT: Whiskeys with maturation periods of 1 to 26 y were analyzed by polyelectrolyte titration at various pH levels. The amounts of charge (polyelectrolyte concentration), which were mainly attributable to polyphenols which were extracted from wood casks during the maturation, were determined. The amounts of charge, namely polyphenols, increased with increasing periods of maturation. On the other hand, the ratio of amounts of charge in the alkaline region compared to those in the neutral region became smaller with longer storage. It was found that polyphenols were extracted over time from the wood cask by whiskey, but they were oxidized to alter the polyphenol compositions, which stabilized clusters (molecular association) between alcohol and water to make whiskeys mellow.     

Characterization of trembling aspen wood (Populus tremuloides L.) degraded with the white rot fungus Ceriporiopsis subvermispora and MWLs isolated thereof

Trembling aspen wood (Populus tremuloides L.) was treated with white rot fungus Ceriporiopsis subvermispora for 1, 2, 4, and 6 weeks. As fungal decay advanced, lignin contents were decreased gradually up to ca. 27.5% (based on the Klason residues of the control) after 6 weeks. Alkali solubility of cell wall residues was increased until 4 weeks of fungal treatment, but additional treatment did not cause any effects. Milled wood lignins (MWLs) were isolated from the decayed woods by Björkman’s procedure and subjected to thioacidolysis and analytical pyrolysis to investigate the modification of lignin structures during fungal degradation. Thioacidolysis revealed that the yields of trithioethylated C₆C₃ monomers, as a parameter for frequency of β-O-4 linkages in lignin, were substantially reduced (-20%, based on the control) in MWLs isolated from decayed woods. Analytical pyrolysis revealed that the relative amounts of coniferyl alcohol and sinapyl alcohol in the pyrolysates were lowered dependent on the biodegradation time, whereas an elevation of C₆C₁ and C₆C₂ pyrolytic phenols was observed. The results from both analytical methods strongly suggested that β-O-4 linkages were cleaved by C. subvermispora. Specially, degradation of syringyl-type lignin seems to be preferred.     

Grape brandy production,composition and sensory evaluation

Grape brandy is a spirit drink produced by wine distillation and is matured in wooden casks. According to legislation, it can be characterised by the geographical area where the grapes were produced, the grape variety used and the selected distillation and ageing techniques. Distillation increases ethanol concentration and aromatic constituents which are already present in grapes or are developed during fermentation and distillation. During maturation in wooden casks, compounds that contribute to the aroma and taste are extracted from the wood. Hence the spirit acquires the desired softer mouth feel, aromatic complexity and overall quality. Different methods of analysis are used in order to pursuit this process by analysing volatile and non‐volatile substances and correlate composition with quality. Analysis can also be useful in identification of brandy safety, potential adulterations, provenance and differentiation from other spirits drinks. © 2013 Society of Chemical Industry     

阔叶木木素和木素-碳水化合物复合体的仿酶降解

本文采用Cu2 + /吡啶 /过氧化氢组成的仿酶氧化系统对蓝桉 (Eucalyptusglobulus)的MWL和LCC进行仿酶降解 ,通过红外光谱分析及气相色谱 /质谱分析 ,解析了MWL和LCC在降解过程中的结构变化 ,并对仿酶降解的机理进行了初步探讨。研究结果表明 :这种仿酶降解方法对MWL和LCC的降解能力较强 ,降解后的产物中羰基和羟基增多 ,而且会使木素中的苯环开裂。紫丁香醛和香草醛等低分子化合物的生成 ,说明木素侧链受到氧化作用 ,致使结构单元之间的连接断裂。本研究可以为开发纸浆的仿酶漂白技术提供理论依据。     

Aging marker profile in cachaça is influenced by toasted oak chips

Cachaça is the most important distilled spirit in Brazil and the fourth most consumed in the world. Aging is not mandatory for cachaça. When aging is carried out, casks generally do not undergo the final wood toasting. However the level of thermal degradation of wood influences the formation of new chemical compounds, which are released during the aging process and improve the quality of the spirit. The objective of this study was to verify the influence of origin of wood and toasting intensity of oak chips on the profile of aging markers in cachaça. Staves of oak wood from the forests of Allier, Vosges and Nièvre (France) were milled and screened at 9 mesh. The chips underwent light, medium and heavy toasting. The toasted chips were added to cachaça (1 g/L) and kept in a closed system at room temperature, without agitation, for 15 days. The aging congeners (gallic acid, 5‐hydroxymethylfurfural, furfural, vanillin, vanillic acid, syringaldehyde, sinapaldehyde, syringic acid and coniferaldehyde) were analysed using HPLC. The increase in toasting intensity enhanced the content of the aging markers in cachaça, especially syringic acid, vanillin, syringaldehyde, coniferaldehyde and sinapaldehyde. The generation of aging marker compounds was influenced only by the toasting intensity and not by the origin of the oak wood. Copyright © 2015 The Institute of Brewing & Distilling     

木聚糖酶预处理对麦草木素结构特征的影响

为了探讨木聚糖酶在麦草碱法化学机械制浆过程中的作用机理,采用13C、1H和2-DNMR光谱技术对木聚糖酶预处理麦草的二氧六环木素进行了研究。分析结果表明:麦草经木聚糖酶处理,木素的羟基和甲氧基数量增加。木聚糖酶处理是"生物"作用,在酶攻击麦草的木素-碳水化合物复合体的脂键或糖键、部分脱出木糖的同时,麦草被"活化"。高清晰度的2D-HMQC NMR技术是分析木素结构的有利工具。     

传统熏烤木材中木质素结构表征及其热解特性

为探究传统熏烤肉制品熏烤时所采用不同化学组成及结构的木材类型对产生有害物质多环芳烃的种类和生成量的影响,以传统熏烤肉制品生产时常用的松木、杨木、榉木、枣木、苹果木5种木材为研究对象,通过红外光谱、拉曼光谱、热重及热重-红外联用分析,考察5种木材中木质素的结构特征及其热解特性。结果表明：5种木材中木质素含量,以及木质素中愈创木基结构单元（G）、紫丁香基结构单元（S）含量均存在差异;热解过程基本可分为3个阶段,主要发生在200～500℃范围内,但是5种木质素的质量损失速率、质量损失温度、热解速率、热解温度均不同,说明不同木质素的热稳定性存在显著差异。熏烤木材中木质素含量,S/G结构含量及侧链结构上差异可导致其热稳定性的不同,而热解特性的不同则进一步影响多环芳烃等有害物的生成。     

Extraction of phenolics from new oak casks during spirit maturation: impact on spirit colour

The increase in colour and solubilisation of extract, polyphenols and ellagitannins were studied in wine spirit in new oak casks over a period of 23 years. Ellagitannins and oak colour were solubilised during the early years of maturation. After five years, the concentration of ellagitannins decreased markedly, while colour increased, although at a lower rate. Ellagitannins were oxidised into coloured polymers and hydrolysed into ellagic acid. The dry extract, containing polysaccharides, polyphenols and lignin, increased throughout maturation, growing quickly during the early years and slowly thereafter. In a model solution, ethanol exhibits a strong solvent effect. For higher concentrations (50% v/v and more), the extraction of colour was faster, and was typically dark yellow/brown with a red tone, attributable in part to the solubilisation of lignin and lignin by-products. © 2020 The Institute of Brewing & Distilling     

A comparative study of hard and softwood lignins alterations during treatment in dioxane-water-HCl agent

The objective of the presented contribution was a study of the lignin alterations occurring in the process of the acidolytic delignification of chosen representatives of soft and hard wood species (maple and spruce) in dioxane-water-HCl mixture. All lignin samples were characterised by yield or recovery, molecular weights, as well as by GLC data of corresponding nitrobenzene oxidation products. In order to obtain more information about condensation and degradative reactions of lignin under conditions of acidolytic treatment a simulation of the process of lignin isolation was performed, too. Samples of dioxane lignins obtained after 90 min. of isolation at 82.5 and 98 °C were therefore recooked during 360 min. under identical conditions as applied in the lignin isolations. Concentrations of lignin in the reaction mixture were 1 and 10% thus approximately corresponding the lignin concentration inside and outside of the wood meal during the lignin isolation. The obtained experimental data point out the course of both degradative and condensation reactions. Maple wood lignin undergo deeper degradation than those of spruce under the same reaction conditions. The decreased yields of lignin oxidation products with the time of acidolytic treatment and after recooking hint at the formation of new linkages among building units of lignin thus modifying its macromolecules. The intensity of occurring alterations of examined lignins is not only dependent of time and temperature, but also of the concentration of lignin.     

Analytical pyrolysis and FTIR spectroscopy of fossil Sequoiadendron giganteum (Lindl.) wood and MWLs isolated hereof

Recent and fossil woods from the genus of Sequoiadendron, as well as their milled wood lignins were investigated by means of FTIR spectroscopy and pyrolysis GC/MS technique. Though almost same in appearance the differences in band intensities of FTIR-spectra reveals the distinctly increased aromatic character and the oxidation in fossil specimens. More detailed information about the changes in old wood were obtained by analytical pyrolysis, which delivers degradation products with shortened side chains and more saturated units relating to fossil lignin.     

Analysis of Isinglass Residues in Beer

A method has been developed for the detection of trace quantities of residual isinglass present in fined beers. Isinglass residues in beer are concentrated by means of an antibody raised using isinglass as an antigen. The separated isinglass is hydrolysed to its constituent acids and quantified by measuring the content of hydroxyproline. The limit of quantification of this method, that is the concentration of isinglass in beer which can be distinguished from background levels of hydroxyproline, is 0.17 mg of isinglass/litre of beer (on an isinglass dry weight basis). This method has been used to quantify the concentration of isinglass residues which could be present in brewery and cask conditioned beers, and also to determine whether there is likely to be stratification of isinglass residues in casks.     

葵花秆木素的结构特征

采用酸解和酶解两种方法对葵花秆进行木素分离,并通过红外和~1H-NMR测定其性能。结果表明,葵花秆髓芯部分木素的氮元素含量比秆部高,酶解木素比酸解木素含量高;另外,与秆部木素相比,髓芯木素中醇羟基含量较高,酚羟基和甲氧基含量较低。而与酸解木素相比,葵花秆的酶解木素醇羟基含量很高,甲氧基含量较低。