Kraft lignin degradation products for tanning and dyeing of leather

Kraft lignin degradation by a biomimetic system was investigated, using hemin as a catalyst and hydrogen peroxide as an oxidising agent, which mimics the catalytic mechanism of lignin peroxidase (LiP) to produce phenolic compounds. The degradation products were identified using spectroscopy and gas chromatography–mass spectrometry (GC–MS): 2‐methoxyphenol, 4‐hydroxybenzaldehyde, vanillin and vanillic acid were produced and their formaldehyde polymerisation products used for tanning hide powders. The denaturation (shrinkage) temperature of hide powder was raised to 80 °C through hydrogen‐bonding interactions between the polymers and the collagenic hide powder. For dyeing of hide powder, the lignin degradation products were reacted with laccase (a polyphenol oxidase): 2‐methoxyphenol gave the darkest colour. These products have potential to be used as raw materials for tanning and dyeing of animal skins. Therefore, value can be added to this industrial byproduct and reduce its environmental impact. Copyright © 2004 Society of Chemical Industry     

Study of Aromatic Compounds Derived from Sugarcane Bagasse. Part I: Effect of pH

This work aims at increasing the knowledge about the recovery of aromatic compounds from the lignin fraction of sugarcane bagasse, as well as exploring the possibility to recover these fine chemicals of great concern for many industrial sectors. The major natural products contained in the lignin fraction of such a straw material were extracted in previous work by alkaline hydrolysis using different concentrations of NaOH and amounts of bagasse, and HPLC analyses revealed that the extracts mainly contained p‐coumaric acid, ferulic acid, syringic acid, and vanillin, the first three containing and the last lacking a carboxyl group. All these aromatic compounds have well‐known antioxidant power and are very important in pharmacology. For these reasons, they have been investigated in this study by UV spectrophotometry, with special concern to the pH effect on their spectra and determination of their pK_a values.     

Study of Aromatic Compounds Derived from Sugarcane Bagasse: II. Effect of Concentration

The results of a set of experiments that were designed to integrate current knowledge on the major constituents of sugarcane bagasse lignin, specifically p‐coumaric, ferulic, syringic acids, and vanillin are presented. These aromatic compounds have well‐known antioxidant power and they are very important for the food, pharmaceutical, and nutraceutical industries. Following a study on the effect of pH upon the spectra of these monomers and the determination of their pK_a values, their self‐association properties in ethanol as a solvent, particularly at concentrations < 10^–4 M were investigated using UV spectrophotometry and their K_ass values were determined. The results collected allowed to better understand the chemistry of sugarcane lignin and provide a contribution to the possible exploitation of this abundant straw material for the recovery of fine chemicals.     

CHEMICAL CHARACTERIZATION OF BEECH CONDENSATE

ABSTRACT

Beech (Fagus sylvatica L.) condensate from a steaming operation was collected and analyzed. The condensate exhibited a low pH, and contained carbohydrates and phenolic compounds. A total of five phenolic acids and aldehydes (syringic acid, vanillic acid, p-hydroxybenzoic acid, syringaldehyde, vanillin) were identified. TLC of the carbohydrates showed the presence of glucose, galactose, xylose, mannose and/or arabinose in the condensate. Fructose, saccharose, raffinose and stachyose were also identified. The COD, BOD5, pH, conductivity and suspended solids (TSS) were determined. The chemical oxygen demand (COD) in the beech condensate varied from 2016 to 1393O mg/L. This value is two to three fold higher than the corresponding biological oxygen demand (BOD₅).     

Arabinosylated phenolics obtained from SO2‐steam‐pretreated sugarcane bagasse

A pentose‐rich hydrolysate fraction obtained by extraction of steam‐pretreated sugarcane bagasse was analysed with regard to dissolved phenolics. The liquid obtained after steam pretreatment (2% SO₂ (w/w) at 190 °C for 5 min) was divided into two parts: one containing dissolved compounds originating from hemicellulose (with xylose as the dominating compound), and the other containing predominantly dissolved compounds originating from lignin. Using nuclear magnetic resonance, the main dissolved compounds originating from lignin were identified as the glycosylated aromatics, 5‐O‐(trans‐feruloyl)‐L‐Arabinofuranose and 5‐O‐(trans‐coumaroyl)‐L‐Arabinofuranose, together with p‐coumaric acid and small amounts of more common free phenolics such as p‐hydroxybenzaldehyde, p‐hydroxybenzoic acid and vanillin. The phenolic compounds were analysed and quantified using reversed‐phase high‐performance liquid chromatography. The findings show that SO₂ steam explosion opened up new degradation pathways during lignin degradation. Copyright © 2012 Society of Chemical Industry     

A Coenzyme‐Independent Decarboxylase/Oxygenase Cascade for the Efficient Synthesis of Vanillin

Vanillin is one of the most widely used flavor compounds in the world as well as a promising versatile building block. The biotechnological production of vanillin from plant‐derived ferulic acid has attracted much attention as a new alternative to chemical synthesis. One limitation of the known metabolic pathway to vanillin is its requirement for expensive coenzymes. Here, we developed a novel route to vanillin from ferulic acid that does not require any coenzymes. This artificial pathway consists of a coenzyme‐independent decarboxylase and a coenzyme‐independent oxygenase. When Escherichia coli cells harboring the decarboxylase/oxygenase cascade were incubated with ferulic acid, the cells efficiently synthesized vanillin (8.0 mM , 1.2 g L ^?1) via 4‐vinylguaiacol in one pot, without the generation of any detectable aromatic by‐products. The efficient method described here might be applicable to the synthesis of other high‐value chemicals from plant‐derived aromatics.     

Pellioditis pellio: Substituted phenolic compounds as chemoattractants

Vanillin, vanillic acid, and other related compounds are chemoattractants either for nematodes or arthropods. We tested vanillin, vanillic acid, and 2,4-dihydroxybenzaldehyde in an in vitro bioassay system for their ability to attractPellioditis pellio males and females. Females were not attracted to any of the three compounds tested. Males responded to vanillin and vanillic acid, but not to 2,4-dihydroxybenzaldehyde. Males responded to vanillin and vanillic acid when these compounds were present at 10^–5 M concentration. Vanillin at 10^–3 and 10^–7 M concentrations was not attractive.     

Comparative study of three lignin fractions isolated from mild ball‐milled Tamarix austromogoliac and Caragana sepium

Six lignin fractions from mild ball‐milled Tamarix austromogoliac (TA) and Caragana sepium (CS) were sequentially isolated with 80% dioxane containing 0.05M HCl at 75°C for 4 h, 50% aqueous ethanol containing 1M triethylamine at 70°C for 4 h, and 8% aqueous NaOH at 45°C for 3 h. The results showed that the successive treatments made it possible to isolate lignin from wood with a high yield and purity, in which 89.4 and 90.6% of the original lignin from TA and CS were released, respectively. The lignin fractions isolated with the three‐step method were analyzed with Fourier transform infrared, ¹H‐ and ¹³C‐NMR, alkaline nitrobenzene oxidation, and gel permeation chromatography. It was found that the three lignin fractions isolated from TA were rich in syringyl units, and the molar ratio of the relatively total moles of vanillin, vanillic acid, and acetovanillin to the relatively total moles of syringaldehyde, syringic acid, and acetosyringone decreased from 1: 2.6 to 1 : 3.2 to 1: 3.6 in the lignin preparations, whereas this ratio in the corresponding lignin fractions isolated from CS was found to be 1.4 : 1, 1.1 : 1, and 1 : 1.4, respectively. More importantly, the results revealed that the sequential extractions of the mild ball‐milled TA and CS with 80% acidic dioxane, 50% alkaline ethanol, and 8% aqueous NaOH under the conditions used did not significantly cleave the β–O‐4 and α–O‐4 linkages in lignin macromolecules. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Oxidation of Hardwood Kraft-Lignin to Phenolic Derivatives. Nitrobenzene and Copper Oxide as Oxidants

A hardwood kraft lignin (obtained by precipitating an industrial black liquor with a solution of calcium salt in alcohol) was oxidized in alkaline medium to obtain phenolic compounds (syringaldehyde, vanillin, syringic acid and vanillic acid). Nitrobenzene and copper (II) oxide were the oxidants employed. Influence of temperature, reaction time and oxidant concentration on yield and product distribution were studied. The results show that nitrobenzene is a more effective oxidant (15–18 % of aldehydes on kraft lignin) than copper (II) oxide (7–8 %). Product distribution showed the highest aldehyde selectivity for nitrobenzene, due to the presence of two additional oxidation products in the copper oxide oxidations. In the oxidation to aldehydes, the alcohol-calcium precipitated kraft lignin is a better raw material than other precipitated kraft lignin.     

Production of vanillin from wheat bran hydrolyzates via microbial bioconversion

BACKGROUND: Wheat bran contains a large amount of ferulic acid, which can be released through enzymatic hydrolysis and bioconverted into vanillin. A previous study has shown that ferulic acid purification from bran carbohydrates with the Amberlite^® IRA 95 resin allowed an increased vanillin molar yield. In this work, alternative ferulic acid recovery methods were proposed and the possibility of exploiting the residual carbohydrate‐rich water phase was explored. RESULTS: Ferulic acid was recovered from crude wheat bran hydrolyzate by: (i) a hydrophobic sorbent cartridge (ISOLUTE ENV^+®): (ii) ethyl acetate extraction; and (iii) the resin previously employed. The highest recovery percentage (95%) was obtained with ISOLUTE ENV^+®, which also allowed an interesting vanillin molar yield from ferulic acid bioconversion (75% from 0.5 mmol L^?1 ferulic acid). The residual water phase was a good growth substrate for the microorganism operating the bioconversion. Cells grown on this matrix could efficiently bioconvert the recovered ferulic acid to vanillin CONCLUSION: The possibility of efficiently recovering ferulic acid from wheat bran hydrolyzates, bioconverting it into vanillin, and valorizing the sugar‐rich exhausted water fraction was demonstrated in this work. The approach allowed the production of a value‐added fine‐chemical from a food‐industry by‐product. Copyright © 2009 Society of Chemical Industry     

Primary Metabolites and Polyphenols in Rapeseed (Brassica napus L.) Cultivars in China

Defatted meals of 10 rapeseed (Brassica napus L.) varieties were investigated for their total phenolic, phenolic acid (free, esterified, and insoluble-bound forms), and tannin contents. The antioxidant capacities (AC) of methanol extracts from samples were assessed using the 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH•), Folin–Ciocalteu method and ferric reducing antioxidant power (FRAP), and β-carotene–linoleic acid tests. In the fraction of free phenolic acids, sinapic, caffeic, ferulic, syringic, gallic, and p-coumaric acids were identified. In the fraction of esterified phenolic acids, sinapine, sinapoyl glucoside, and disinapoyl gentiobiose were identified. After basic hydrolysis, sinapic, ferulic, cinnamic, and 4-hydroxybenzoic acids were identified, and sinapic acid (SA) constituted 98.3% to 99.6% of the total esterified phenolic acids. Eleven components (sinapic, protocatechuic, p-coumaric, syringic, vanillic, gallic, caffeic, ferulic, salicylic, cinnamic, and 4-hydroxybenzoic acids) in the fraction of insoluble-bound phenolic acids were identified. The AC of the samples correlated with the total phenolic content. Overall, the total phenolics showed a better correlation with AC than the individual phenolic compounds. Moreover, SA, sinapoyl glucoside, and disinapoyl gentiobiose showed a highly significant and strong positive correlation with the AC of rapeseed meals, and the derivatives of cinnamic acid showed a higher correlation with AC than the derivatives of benzoic acid. The change in the canolol content in rapeseeds under microwave irradiation is discussed. The correlation of the canolol formed with SA and its derivatives is discussed.     

Statistical optimization of process parameters for the production of vanillic acid by solid‐state fermentation of groundnut shell waste using response surface methodology

BACKGROUND: Vanillic acid is a flavoring agent and also serves as precursor for vanillin production. Culture medium and fermentation condition for the single step production of vanillic acid from Phanerochaete chrysosporium using lignocellulosic waste as a substrate under solid state fermentation (SSF) were optimized using response surface methodology. RESULTS: The process parameters were chosen by borrowing methodology, and L‐asparagine, pH and moisture content of the solid medium during SSF were identified as the most significant variables. The optimum value of selected variable and their mutual interactions were determined by response surface methodology. The result demonstrated that a yield of 73.58 mg vanillic acid g^?1 substate was predicted under optimum conditions (L‐asparagine 5.98 mmol L^?1 (2.37 mg g^?1 groundnut shell), pH of solid medium 4.51 and moisture content 74.83%). The predicted response was experimentally validated and resulted in a maximum vanillic acid yield of 73.69 mg g^?1 after 8 days of SSF. CONCLUSION: The optimization of fermentation variables resulted in a maximum 10‐fold increase in vanillic acid yield compared with that observed under sub‐optimal conditions (from 7.2 mg g^?1 to 73.69 mg g^?1). Copyright © 2011 Society of Chemical Industry     

Comparative Study of Ozonation of Two Lignin Model Compounds: Coniferyl Alcohol and Ferulic Acid. Identification of some by-Products

The objective of our study was to compare the reactivity of coniferyl alcohol and ferulic acid with ozone at acidic pH in terms of ozone demand and byproducts formation. Both structures exert an ozone demand of about two moles of ozone per mole of initial compound. Similar ozonation byproducts were identified using gas chromatography/mass spectrometry analysis. Using a low ozone dose (below the ozone demand), byproducts were principally aromatic structures, with vanillin, 3,4-dihydroxy-5-meth-oxybenzaldehyde and vanillic acid as the main compounds. Applying a higher ozone dose (above the ozone demand), furan structures were produced. A reaction mechanism is suggested to explain the formation of such structures. A quantitative study showed that coniferyl alcohol was a stronger precursor of vanillin and vanillic acid than ferulic acid.     

Effect of bacterial inoculum ratio in mixed culture for decolourization and detoxification of pulp paper mill effluent

BACKGROUND: Effluent released from industry is a mixture of various pollutants. For the degradation of complex pollutants, mixed bacterial cultures can be more effective than a single culture. This study investigated the balance of bacterial populations in a mixed culture for maximum reduction of pollutants. RESULTS: This study deals with the degradation and detoxification of pulp paper mill effluent (PPME) by three bacterial strains, i.e. Serratia marcescens, Serratia liquefaciens and Bacillus cereus in different ratios, and found that two ratios, 4:1:1 and 1:4:1, were effective for the degradation of PPME. These ratios reduced the various pollution parameters. Enzyme bioassay revealed that more enzyme was produced during degradation for the ratio 4:1:1. High performance liquid chromatography (HPLC) analysis showed that the ratio 4:1:1 degraded 95% of lignin and related compounds, and chlorophenols up to 98%, whereas ratio 1:4:1 reduced lignin by 84% and chlorophenols by 58% after 7 days incubation. Degradation products were confirmed by gas chromatography–mass spectrometry (GC‐MS) analysis. A seed germination bioassay on Phaseolous mungo L. revealed that toxicity was reduced by the ratio 4:1:1. CONCLUSION: Due to variable potential of different bacteria show variation in their growth pattern at any contaminated site. This study shows that an appropriate ratio of mixed cultures is required for maximum degradation and detoxification of PPME. Copyright © 2012 Society of Chemical Industry     

Microbial decomposition of ferulic acid in soil

The suppression of plant growth by different phenolic acids is well known. This work was designed to determine if ferulic acid, a known phenolic inhibitor of plant growth, accumulates in the soil and if soil microorganisms could be isolated that metabolize it. Over 99% of the extractable ferulic acid was lost from decaying hackberry leaves in 300 days. During this time the amount in the top 15 cm of soil remained fairly constant at about 30 ppm, except for the March sample which was significantly higher than the rest. Addition of ferulic acid to soil caused an increase in CO₂ evolution and in numbers of a select group of microorganisms.Rhodotorula rubra andCepnalosporium curtipes, which actively metabolize ferulic acid, were isolated, but the metabolic pathways employed appear to be different from the reported one. The reported pathway for ferulic acid breakdown is ferulic acid to vanillic acid to protocatechuic acid to -keto-adipic acid.Rhodotorula Rubra was found to convert ferulic acid to vanillic acid, but no evidence was found for utilization of the rest of the pathway.Cephalosporium curtipes appears to use a different pathway or to metabolize intermediate compounds rapidly without accumulating them, because no phenolic compounds were found during the breakdown of ferulic acid. The presence in the soil of microorganisms that metabolize ferulic acid and other phenolic acids is ecologically significant because such organisms prevent long-term accumulations of these substances, which are toxic to many other microorganisms and higher plants.     

Lignin organosolvolysis from autohydrolyzed corn (Zea mays) stalks: Ozonation of both solvolytic solid and juice

The solubility of lignin from autohydrolyzed corn (Zea mays) stalks in different organic solvent–water mixtures and conditions was studied. The best lignin solvent was selected according to its lignin extraction capacity and its low reactivity to ozone. Both the organosolvolytic solid and juice obtained in optimal conditions, 75/25 (v/v) acetone–water mixture at 210°C for 45 min, and the autohydrolyzed material were treated with ozone, and the reaction products were determined by gas chromatography–mass spectrometry and gas chromatography–flame ionization detection. The concept of the solubility parameter (δ-value) was applied to explain the effect of the solvent-to-water ratio on lignin solubility. The δ-value of the lignin dissolved was 13.8 (cal/cm³)^1/2. The δ-value of the various solvent–water mixtures was also calculated. The experimental delignification capacity of the aqueous organic solvents clearly reflects the proximity of their δ-value to that of lignin. In other words, the closer the δ-value of the aqueous organic solvent to that of lignin, the more effective it is; the hydrogen-bonding capacity of the solvent–water mixtures was also taken into account. The following acids were identified during ozonation: glycolic, oxalic, malonic, glyoxylic, butanedioic, malic, p-hydroxybenzoic, vanillic, and syringic. In addition, syringaldehyde, vanillin, p-hydroxybenzaldehyde, and hydroquinone were identified. Ozonation of theorganosolvolytic juice led to the formation of the oxyaromatic compounds, which were destroyed during treatment. This destruction was accompanied by the generation of aliphatic acids. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1867–1876, 1998     

Black liquor detoxification by laccase of Trametes versicolor pellets

Black liquors from a soda pulping mill were treated with the white‐rot fungus Trametes versicolor to detoxify and reduce colour, aromatic compounds and chemical oxygen demand (COD). The fungus was used in the form of pellets in aerated reactors (fluidized, stirred and air‐pulsed reactors). Reductions in colour and aromatic compounds of 70–80% and in COD of 60% were achieved. During the different experiments, laccase activity was detected but neither lignin peroxidase (LiP) nor manganese peroxidase activities were detected, although T versicolor is able to produce these enzymes. Experiments also showed a LiP activity inhibitory effect produced by lignin. From the results obtained, it can be concluded that there is a relationship between laccase production and toxicity reduction. This correlation responds to the equation Laccase production = 1.57 LN (toxicity reduction) ?16.40. Copyright © 2003 Society of Chemical Industry     

Separation of Phenolic Compounds from Sugarcane Bagasse Pith and Their Determination by HPLC

Three chromatographic techniques were compared to determine the solubilized phenolic compounds, from sugarcane bagasse pith pretreatment. Reverse phase gradient system I, was chosen as a technique to be evaluated in aromatic compounds determination, because it presented good selectivity, reproducibility and percent recovery of phenolic compounds. However, gradient system II, and ionic exchange, resulted in longer resolution time, even though they had good resolution and selectivity. The amount of aromatic compounds determined by reverse phase gradient elution, were in decreasing order: 4-hydroxycinnamic acid (p-coumaric acid), 4-hydroxy-3-methoxycinnamic acid (ferulic acid), 4-hydroxybenzaldehyde (p-hydroxybenzaldehyde), 4-hydroxy-3-methoxybenzaldehyde (vanillin), and 4-hydroxy-3-methoxybenzoic acid (vanillic acid).

Reverse phase gradient system I, can be useful to identify and quantify the phenolic compounds solubilized in other lignocellulosic materials.

From the experimental design 2³, the most important effect on total phenolic compounds solubilization, were: alkali concentration, temperature and alkali-moisture content interaction. In addition, the maximum amount of these compounds were obtained at high levels of experimental conditions, that is; 10% Na0H (ODW), 50°C of temperature, and 80% of moisture content.     

Adsorption of colour from a bleach plant effluent using biomass and cell wall fractions from Rhizomucor pusillus

Relatively high decolourisation of bleach plant effluent (41%–48%) could be attained in short treatment times using biomass of Rhizomucor pusillus, a mucoralean fungus. Cell wall fractions (alkali‐resistant, residual and chitosan fractions) extracted from the R pusillus biomass appeared to be mainly responsible for the adsorption of chromophores from bleach plant effluent by this fungus. The alkali‐resistant fraction removed 34% of the colour from bleach plant effluent. Although the residual and chitosan fractions represented only about 12% of the total dry biomass, they removed more colour from bleach plant effluent (41%) than did the intact biomass (39%). The chitosan and residual cell wall fractions, mainly composed of chitin and/or chitosan, seem to be involved in the mechanism of colour removal from bleach plant effluent by R pusillus. © 2002 Society of Chemical Industry     

Phenolic Characterization and Geographical Classification of Commercial Extra Virgin Olive Oils Produced in Turkey

The aim of this research was to characterize the extra virgin olive oil samples from different locations in the Aegean coastal area of Turkey in terms of their phenolic compositions for two consecutive years to show the classification of oil samples with respect to harvest year and geography. Forty seven commercial olive oil samples were analyzed with HPLC–DAD, and 17 phenolic compounds were quantified. Hydroxytyrosol, tyrosol, vanillic acid, p-coumaric acid, ferulic acid, cinnamic acid, luteolin and apigenin were the characteristic phenols observed in all oil samples for two harvest years. Syringic acid, vanillin and m-coumaric acid were the phenolic compounds appeared in the olive oil depending on the harvest year. Partial least square-discriminant analysis (PLS-DA) of data revealed that oils from the north Aegean and south Aegean areas had different phenolic profiles. The phenolic compounds, which played significant roles in the discrimination of the olive oils, were tyrosol, oleuropein aglycon, cinnamic acid, apigenin and hydroxytyrosol to tyrosol ratio. The Aegean coastal region is the largest olive oil producer and exporter of Turkey. This study shows that the olive oils from different parts of the region have their own defining characteristics that can be used in the authentication studies and geographical labeling of Turkish olive oils.