4-ethylguaiacol Research Articles

Iron oxyhydroxide catalyzes production of artificial humic substances from waste biomass

Production of artificial humic substances (AHS) from waste biomass will contribute to environmental protection and agricultural productivity. However, there is still a lack of a faster, more efficient and eco-friendly way for sustainable production. In this study, we proposed a method to accelerate the production of AHS from cotton stalks by mild pyrolysis and H2O2 oxidation in only 4 hours, and investigated the formation of AHS during biomass transformation. We found that the process increased the aromatic matrix and facilitated biomass transformation by enhancing the depolymerization of lignin into micromolecular phenolics (e.g., guaiacol, p-ethyl guaiacol, etc.). The optimum conditions of pyrolysis at 250 °C and oxidation with 6 mL H2O2 (5 wt%) yielded up to 19.28 ± 1.30 wt% artificial humic acid (AHA) from cotton stalks. In addition, we used iron oxyhydroxide (FeOOH) to catalyze biomass transformation and investigated the effect of FeOOH on the composition and properties of AHS. 1.5 wt% FeOOH promoted the increased content of artificial fulvic acid (AFA) in AHS from 10.1% to 26.5%, eventually improving the activity of AHS. FeOOH raised the content of oxygen-containing groups, such as carboxylic acids and aldehyde, and significantly increased polysaccharide (10.94%–18.95%) and protein (1.95%–2.18%) derivatives. Polymerization of amino acid analogs and many small-molecule carbohydrates (e.g., furans, aldehydes, ketones, and their derivatives) promoted AFA formation. Finally, carbon flow analysis and maize incubation tests confirmed that AHS were expected to achieve carbon emission reductions and reduce environmental pollution from fertilizers. This study provides a sustainable strategy for the accelerated production of AHS, which has important application value for waste biomass resource utilization.

Characterization and comparison of key aroma compounds in traditional and rapid Yongchuan douchi by molecular sensory science

Yongchuan douchi is a famous soybean product that is widely used as a condiment in China due to its attractive aroma and can be categorized into traditional and rapid Yongchuan douchi (TYD and RYD). However, the key aroma compounds in TYD and RYD and their differences remain poorly understood. In the present study, the key aroma compounds in TYD and RYD were characterized and compared by a molecular sensory approach. The results obtained by multidimensional gas chromatography-mass spectrometry/olfactometry (MDGC−MS/O) demonstrated that a total of 125 volatiles and 71 aroma-active compounds were identified. Moreover, 36 aroma-active compounds with relative odor activity values (rOAVs) ≥ 1 and flavor dilution (FD) ≥ 16 were screened and quantified by an external standard method. The recombination and omission experiments revealed that TYD and RYD contained 18 and 13 key aroma compounds, respectively. TYD and RYD contained 10 identical compounds, whereas 8 (ethyl 2-methylbutyrate, ethyl 3-methylbutyrate, ethyl isobutyrate, ethyl caproate, ethyl acetate, ethyl benzoate, 4-methyl-2-phenyl-2-pentenal, acetophenone) and 3 (phenylacetaldehyde, 4-ethyl guaiacol, 4-hydroxy-2,5-dimethyl-3(2H)-furanone) were unique to TYD and RYD, respectively. This is the first report of key aroma compounds in TYD and RYD, and it provides insights into improving the aroma of Yongchuan douchi.

Characterization of the key aroma compounds in soy sauce by gas chromatography-mass spectrometry-olfactometry, headspace-gas chromatography-ion mobility spectrometry, odor activity value, and aroma recombination and omission analysis.

Most previous studies on volatile compounds in soy sauce were performed by gas chromatography-mass spectrometry (GC-MS). In this study, the volatile compounds of high-salt liquid-state fermentation soy sauce (HLFSS) were analyzed qualitatively and quantitatively by GC-MS and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). One hundred and seventy-four substances were detected using the two instruments, 87 by HS-GC-IMS and 127 by GC-MS. Aldehydes (26), ketones (28), esters (29), and alcohols (26) were the main compounds in HLFSS. In addition, ethyl pyruvate, (E)-2-pentenal and diethyl propanedioate were detected by HS-GC-IMS, which were previously not detected in HLFSS. Forty-eight aromatics including 34 key ones were identified by gas chromatography-olfactometry. Phenylacetaldehyde, methional, 2-methylbutanal, 1-octen-3-ol, ethyl acetate, 2-ethyl-4-hydroxy-5-methyl-3(2H)-furanone, 4-hydroxy-2,5-dimethyl-3(2H)-furanone and 4-ethyl guaiacol were identified as the main aroma compounds in HLFSS by aroma recombination and omission test. This study laid foundation for developing flavor assessment standards for soy sauce.

Depolymerization of technical lignin to valuable platform aromatics in lower alcohol without added catalyst and external hydrogen

Depolymerization of technical lignin to platform aromatic monomers can significantly increase the productivity and profitability of biorefinery. Establishing an efficient and economical way for technical lignin depolymerization is vital to make this process practical. Herein, we report the one-pot depolymerization of technical lignin into aromatic monomers without added catalyst and external H2 gas. Ethanol, as an inexpensive and recyclable solvent, was used to induce the technical lignin hydrogenolysis. The significant solubility and H-transfer ability of ethanol resulted in an exceptional hydrogenolysis efficiency of the β-O-4 lignin linkages, giving an aromatic monomer yield of 20.62C% at 300 °C for 4 h, rival those from technical lignin disassembly with metal catalysts and added H2 gas. Over 14.70C% of the monomers could be identified, among which phenol, guaiacol, 4-ethyl phenol, 4-ethyl guaiacol, and syringol were obtained with prominent yields. The depolymerization procedure was thoroughly recognized with GC × GC–MS, GPC, MALDI-TOF-MS, HSQC NMR, and FT-ICR-MS analyses to provide an in-depth understanding of the molecular weight, functionality, and elemental composition evolutions of the technical lignin.

Target-based virtual screening and molecular interaction studies for lead identification of natural olive compounds against glioblastoma multiforme.

Glioblastoma multiforme, a rare traumatic brain disorder, is at the research climax for its uncontrolled growth leading to a catastrophic outcome. Throwing light on the target-based virtual screening of drugs using natural phytocompounds is a striking cornerstone in glioblastoma-based drug discovery, accelerating with leaps and bounds. This project aims to develop promising lead compounds against glioblastoma brain cancer using OliveNet™, an open-source database. In this pursuit, our rationale for selecting molecules was based on their capability to pass through the blood-brain barrier. Out of 51 derivative molecules from flavonoids and polyphenols, 17 molecules were screened out bearing the best ADMET (absorption, distribution, metabolism, excretion, and toxicity) properties, alongside fulfilling our rationale of lead selection. Two polyphenols, 3,4,5-trimethoxybenzoic acid and 4-ethyl guaiacol, have binding affinity for the antioxidant flavonoid luteolin of -5.1 and -4.3 kcal/mol, respectively. According to docking studies, the residues ASN1960, ASN1966, ASN1960, PHE1984, TYR1896, VAL1911, and LYS1966 make both polar and nonpolar interactions with 3,4,5-trimethoxybenzoic acid and 4-ethylguanidine, respectively. LD50 values of toxicity screening using TOX Pro brought to limelight the excellent safety profile of polyphenols and flavonoids. Furthermore, studies using in silico cytotoxicity prediction and molecular modelling have decisively shown that these polyphenols are likely to be effective brain cancer inhibitors and promising future lead candidates against glioblastoma multiforme.

Selective production of guaiacol from lignin via catalytic transfer hydrogenolysis using Ru-Cu/Zirconia

In this study, the effect of calcination temperature of zirconia support (400, 600, and 800 °C) and the role of bimetallic Ru-Cu over monometallic (Cu, Ru) catalysts are evaluated for catalytic transfer hydrogenolysis of alkali lignin. The prepared catalysts were characterized extensively for crystallinity, pore size distribution, acidity, thermal stability and chemical oxidation state. The transformation of zirconia from non-crystalline to crystalline phase was observed with increasing calcination temperature. The pores transformed from wide ink bottle shape into cylindrical shape with increased calcination temperature. The XPS analysis revealed the existence of Cu0 (60%) in presence of Ru with a concomitant reduction in Ru4+ on the surface of the catalyst, which is attributed to increased crystallinity of zirconia in the presence of copper. High yields of total monomers (32.4 wt.%) and guaiacol (12.7 wt.%) were obtained under the optimized condition (270 °C, 3 h) with Ru-Cu/ZrO2 when ZrO2 was calcined at 800 °C. The mesoporous nature of zirconia and the strong metal-support interaction exhibited by Ru-Cu are shown to influence the formation of monomers. Increase in temperature from 225 to 270 °C enhanced the yield of guaiacol, 4-methyl guaiacol and 4-ethyl guaiacol with a concomitant reduction in the yield of trans-isoeugenol, demonstrating the cleavage of C–C bonds. The recyclability tests of the catalyst showed that the yield of guaiacol remained stable even after two cycles of catalyst reuse without calcination.

Aroma Profile of Monovarietal Pét-Nat Ciders: The Role of Croatian Traditional Apple Varieties

The aromatic and sensory profiles of monovarietal sparkling ciders made according to the modified Méthode Ancestrale or Pétillant Naturel (Pét-Nat) method were established. Three Croatian traditional apple varieties (‘Božićnica’, ‘Bobovac’, and ‘Crvenka’) were basic raw materials for Pét-Nat ciders in this study. The basic apple must and cider parameters were determined by applying OIV methods and nitrogenous compounds, total phenols, and color parameters were analyzed by spectrophotometer. Volatile compounds in final Pét-Nat ciders were determined by SPME-Arrow-GC/MS method and Odor Active Values (OAV) were calculated. The results show that variety significantly altered the pH value, color, aromatic and sensory profile of Pét-Nat ciders. The main contributors (OAV > 1) to the aroma of all Pét-Nat ciders were 1-hexanol, 1-propanol, (6Z)-nonen-1-ol, 1-dodecanol, hexanoic, octanoic and isovaleric acid, citronellol, ethyl hexanoate, ethyl butanoate, ethyl-9-decenoate and isoamyl acetate, eugenol and methionol. ‘Božićnica’ Pét-Nat was differentiated by a high concentration of 1-decanol and 4-ethylphenol, ‘Bobovac’ by 4-vinyl guaiacol and ‘Crvenka’ by 4-ethyl guaiacol. Sensory analysis showed that the highest rated overall quality was attributed to ‘Crvenka’ Pét-Nat cider, with the high-quality color, fruity odor (‘apple’,’apple juice/compote’, ‘pineapple’, and ‘buttery’) and well-balanced taste. This research demonstrates the possibilities in the production of natural sparkling cider from traditional Croatian apple varieties by analyzing the composition and quality of the final product for the first time.

Mechanistic study on the depolymerization of typical lignin-derived oligomers catalyzed by Pd/NbOPO4

The depolymerization mechanisms of lignin-derived oligomers over Pd/NbOPO4 catalyst were investigated by Density Functional Theory (DFT) calculations. Taking the lignin-derived typical small molecular oligomer obtained from pubescens solvolysis as an example, the formation of 4-substituted syringol and 4-ethyl guaiacol products was explored on the surface of NbOPO4 (100) and Pd55 cluster. The synergistic effect of the two kinds of active phase in depolymerization of oligomer was revealed. The NbOPO4 facilitated the breakage of β-O-4 and C-O ester bond in the two dimer fragments (O-I and O-II) from oligomer, due to strong interaction between Nb and O atoms in the dimers. The energy barriers were predicted to be 0.14 eV for β-O-4 bond cleavage and 0.92 eV for C-O ester bond, respectively. The Pd catalyst promoted C-C bond cleavage and hydrogenation in the subsequent transformation. The Cα-Cβ bond breakage was the RDS in the degradation of aldehyde (Frag-2) to 4-methyl syringol. While Cβ-Cγ bond breakage was the RDS in transformation of the acid (Frag-3) and alcohol (Frag-4) fragments, with the energy barriers of 1.73 eV and 1.36 eV, respectively. Moreover, the energy barrier for the conversion of carboxyl group to aldehyde group in Frag-3 was 1.60 eV. In these processes, ethylene, aldehyde or CO2 were released, accompanied by the formation of 4-substituted syringols and 4-ethyl guaiacol products. The mechanistic insights gained from this study could provide useful information for the design of new catalyst for the depolymerization and conversion of oligomers derived from lignin.

Beer ethanol and iso-α-acid level affect microbial community establishment and beer chemistry throughout wood maturation of beer

Sour beers produced by barrel-aging of conventionally fermented beers are becoming increasingly popular. However, as the intricate interactions between the wood, the microbes and the beer are still unclear, wood maturation often leads to inconsistent end products with undesired sensory properties. Previous research on industrial barrel-aging of beer suggests that beer parameters like the ethanol content and bitterness play an important role in the microbial community composition and beer chemistry, but their exact impact still remains to be investigated. In this study, an experimentally tractable lab-scale system based on an in-vitro community of four key bacteria (Acetobacter malorum, Gluconobacter oxydans, Lactobacillus brevis and Pediococcus damnosus) and four key yeasts (Brettanomyces bruxellensis, Candida friedrichii, Pichia membranifaciens and Saccharomyces cerevisiae) that are consistently associated with barrel-aging of beer, was used to test the hypotheses that beer ethanol and bitterness impact microbial community composition and beer chemistry. Experiments were performed using different levels of ethanol (5.2 v/v%, 8 v/v% and 11 v/v%) and bitterness (13 ppm, 35 ppm and 170 ppm iso-α-acids), and beers were matured for 60 days. Samples were taken after 0, 10, 20, 30 and 60 days to monitor population densities and beer chemistry. Results revealed that all treatments and the maturation time significantly affected the microbial community composition and beer chemistry. More specifically, the ethanol treatments obstructed growth of L. brevis and G. oxydans and delayed fungal growth. The iso-α-acid treatments hindered growth of L. brevis and stimulated growth of P. membranifaciens, while the other strains remained unaffected. Beer chemistry was found to be affected by higher ethanol levels, which led to an increased extraction of wood-derived compounds. Furthermore, the distinct microbial communities also induced changes in the chemical composition of the beer samples, leading to concentration differences in beer- and wood-derived compounds like 4-ethyl guaiacol, 4-ethyl phenol, cis-oak lactone, vanillin, furfural and 5-hydroxymethyl furfural. Altogether, our results indicate that wood-aging of beer is affected by biotic and abiotic parameters, influencing the quality of the final product. Additionally, this work provides a new, cost-effective approach to study the production of barrel-aged beers based on a simplified microbial community model.

Catalytic depolymerization of lignin into monophenols over an amorphous mesoporous geopolymer monolith

A new economical, stable, and recyclable amorphous mesoporous geopolymer monolith (GM) was prepared from metakaolin and slag. The obtained GM contained a porous structure mainly with mesopores, and rich Brønsted and Lewis acid sites, which showed higher activity than Ni/MCM-41 and Pt/NiAl2O4, etc. Over 45 aromatic compounds, including guaiacol, syringol, isovanillin, 3,4-dimethoxybenzyl alcohol, etc., were found in the bio-oil. Under optimal conditions, the total yield of 10 major monophenols reached 74.69 ± 1.00 mg/g, half of which was 4-ethyl guaiacol (36.77 ± 1.89 mg/g). Moreover, the GM was easy to regenerate and reuse. In three consecutive runs, the catalytic activity of GM was only reduced by 6.69% per cycle. The synergism of Brønsted and Lewis acidic sites and mesopores of GM was responsible for the high catalytic activity. These indicate the GM is low-cost, easy to prepare, environmentally benign, stable, recyclable, and has great potential in depolymerizing lignin into monophenols.

Characterizing microbial community and metabolites of Cantonese soy sauce

The present researches aimed to investigate the difference of metabolites and the microbial community diversity among batches of Cantonese soy sauce. These results indicated that a higher abundance of lactic acid bacteria, such as Weissella, Lactobacillus originated from koji, in the initial moromi inhibited functional microbes' propagating and metabolizing, wild fungi became dominant. Therefore, the contents of dominant metabolites, including non-volatiles and volatiles as well as their species identified were significantly different. The content of dominant volatiles (Odor Activity Value, OAV >1) were 47.81%, 58.36% and 58.13%, respectively in batch 1, batch 2 and batch 3. This volatiles included ethanol, 3-methyl-1-butanol, 1-octen-3-ol, phenethyl alcohol, acetic acid, 4-ethyl guaiacol. Compared with batch 1, the contents of acetic acid and Ala increased, while that of Glu and esters decreased significantly in the samples of the other two batches. Their flavor characteristics were different from the commercial samples’ based on the Orthogonal Partial Least Squares Discrimination Analysis (OPLS-DA) and Principal Component Analysis (PCA) results due to higher content of acetic acid. Meanwhile, the strength of enzymes expression related with dominant compounds was differentiated. These results were conducive to regulating the process so that improving the quality of soy sauce.

Relating starter cultures to volatile profile and potential markers in green Spanish-style table olives by compositional data analysis

This work relates native lactic acid bacteria (LAB) (Lactobacillus pentosus LPG1, L. pentosus Lp13, and Lactobacillus plantarum Lpl15) and yeast (Wickerhamomyces anomalus Y12) starters to the volatile components (VOCs) produced in green Spanish-style table olives. For this aim, the VOC profile was considered as compositional data (CoDa). The CoDa analysis generated new information on the relationship among inocula and VOCs through the tetrahedral plot, CoDa-biplot, variation array matrix, and CoDa dendrogram. The ilr (which includes pivot) coordinates (Euclidean space) from VOCs produced more reliable starters’ clustering than the original data. The potential VOC markers, identified by a test based on the pairwise comparison of the logratio variation arrays from the whole data set and the individual groups, were (starters in the parenthesis): 2-phenylethyl acetate (LPG1, Y12, Y12 + LAB), methanol (Lpl15), cis-2-penten-1-ol (LPG1, Y12, Y12 + LAB), 2-methyl-3-hexanol (LPG1, Y12), U (non-identified) C (m/z 83-112-97) (Y12) and UF (m/z 95-154-110) (LPG1, Y12 + LAB). Besides, some VOCs were partial/totally inhibited by specific starters: 2-methyl-1-propanol (Lp13, Y12 + LAB), 2-phenyl ethanol (Lp13), furfuryl methyl ether (Y12 + LAB), purpurocatechol (Y12, Y12 + LAB), 4-ethyl guaiacol (Lp13, Lpl15), 4-ethyl phenol (Lpl15), 5-tert-butylpyrogallol (Lp13, Lpl15), and UE (m/z 111–198) (Lp13). A better understanding of the relationship between starters and their VOC may facilitate modelling the flavour and quality of Spanish-style green table olive fermentations.

Odour active compounds determined in the headspace of yellow and black plum wines (Prunus domestica L.)

Odour active compounds (OACs) from the headspace of yellow and black plum wines (Prunus domestica L.) were analysed using gas chromatography-mass spectrometry-olfactometry (GC-MS-O). Olfactometry was conducted using aroma extract dilution assay, through varying split ratios during injection. A total of 18 OACs were determined in the wine headspace including esters, ketones, sulfur containing compounds, alcohols, a terpene, and phenolic compounds. Thirteen of volatile compounds differed significantly (p < 0.05) in concentration between plum wines. Unique OACs were also detected within the headspace that distinguished the wines, where 4-ethyl guaiacol was only detected in the yellow plum wine and diacetyl was only detected within the black plum wines. The remaining nine OACs were not significantly different from each other, suggesting their ubiquity in the plum wines. High flavour dilution (FD) values were determined for ethyl isobutyrate, ethyl 2-methyl butyrate, β-damascenone, and ethyl cinnamate. All compounds detected in the plum wines have been previously reported in grape wine and demonstrated the commonality of volatile constituents between plum and grape wine. However, the very high concentration of β-damascenone may strongly contribute to the overall aroma of the plum wines.

Catalytic depolymerization of organosolv lignin to phenolic monomers and low molecular weight oligomers

The lignin-first strategy provides significant potential for producing value-added phenolics and high-quality biofuels. In this contribution, stepwise extraction and depolymerization of lignin in corncob residue towards the production of phenolic monomers, lignin-derived dimers and trimers was investigated. H2O/n-butanol (4:6, v/v) co-solvent could extract 87.1% of lignin in corncob residue, retaining a high-purity (86.0%) cellulose pulp. Ni/HZSM-5 catalysts with different Ni loadings were prepared and applied for further degradation of organosolv lignin. Over 5% Ni/HZSM-5, the highest yield of phenolic monomer was 19.5% with the selectivity of 66.7% towards 4-ethyl phenols (4-ethyl phenol and 4-ethyl guaiacol) at 300 °C, and liquid products with higher heating value (HHV) of 29.2 MJ kg−1 were obtained. The 5% Ni/HZSM-5 catalyst promoted the cleavage of intramolecular β-O-4 and Cβ-Cγ linkages, resulting in substantially decreased weight-average molecular weight (Mw)/number-average molecular weight (Mn) of the organosolv lignin from 2541/1064 Da to 562/391 Da, which implied the degradation of high-Mw oligomers to dimers and trimers. The catalyst also contributed to the hydrogenation of CαCβ bonds in unsaturated intermediates (coniferyl alcohol and coumaryl alcohol). The possible cleavage mechanism for the degradation of lignin-derived oligomers was also proposed.

Characterisation of volatile compounds in Maotai flavour liquor during fermentation and distillation

Volatile constituents in raw liquor and zaopei during fermentation and distillation were investigated by gas chromatography. Zaopei (steamed grains mixed with Daqu [FG1], stacking fermented grains [FG2], anaerobic fermented grains [FG3] and steamed grains [FG4]) presented changes in physicochemical properties. In all, 72 volatile compounds were identified in zaopei and raw liquor with similarity across 12 zaopei preparations. Principal component analysis and partial least squares discriminant analysis differentiated FG3 from other samples based on content of aroma compounds. FG3 had the highest level of aroma compounds, which increased from the fourth to sixth batches, and was characterised by the presence of 1, 2-propanediol, acetic acid and linoleic acid, while the others were portrayed by phenylpropionate, ethyl laurate and 4-ethyl guaiacol. The volatile compounds of raw liquor were dominated by ethyl acetate and ethyl lactate. Correlation analysis illustrated a lack of correlation of volatile compound content between the raw liquors and the zaopei distillation variants. © 2019 The Institute of Brewing & Distilling

Evolution of the volatile flavor compounds of Chinese horse bean-chili-paste

The production of Chinese horse bean-chili-paste (CHCP) involves three fermentation phases: a chili-to-moromi phase, a horse bean-to-meju phase and a moromi-meju mixed fermentation phase. In consideration of raw materials and fermentation phases, the evolution of key volatile flavor compounds in CHCP were investigated in this study by using GC-MS, olfactometry and principal component analysis. Results showed that there were 22 key flavor compounds in CHCP. Among which, (E)-2-nonenal, nonanal and 3-methyl-1-butanol were primarily from chili, and 1-octen-3-ol was from horse bean. Ethyl decanoate and linalool were mainly formed during the chili fermentation, while ethyl isobutyrate, phenylethyl alcohol and benzene acetaldehyde were found closely related to the horse bean-to-meju process. The mixed fermentation of chili moromi and horse bean meju was significant for the accumulation of 13 key compounds, including 2-methyl-1-butanol, 3-methyl butyraldehyde, 2-methyl butyraldehyde, ethyl isovalerate, ethyl hexanoate, ethyl benzoate, ethyl phenylacetate, guaiacol, 4-ethyl phenol, 4-ethyl guaiacol, 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF), 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone (HEMF) and 3-(methylthio) propanal. Results are conducive to understand the accumulation mechanism of CHCP flavor compounds and promote the quality improvement.

Selective depolymerization of lignosulfonate via hydrogen transfer enhanced in an emulsion microreactor

An efficient emulsion microreactor was constructed for selective conversion of lignosulfonate via hydrogen transfer reaction based on the self-surfactivity of this natural aromatic polymer. Industrial Raney Ni and isopropanol were used as catalyst and hydrogen donor, respectively. The results showed that the emulsion microreactor has a remarkable process intensification effect on the lignosulfonate depolymerization. Under mild condition of 473 K for 2.0 h, 116.1 mg g−1 of volatile phenolic monomer can be obtained, which is twice of that from other investigated processes without emulsion of this work. In particular, 39.3 mg g−1 of which is composed of 4-ethyl guaiacol, an important and versatile chemical currently from petrochemical industry. Furthermore, the solvent separates to two phases automatically after reaction due to the consumption of lignosulfonate, which makes handy products enrichment and separation. Additionally, the emulsion microreactor is significantly affected by hydrogen donor and is efficient for other lignin sources as well.

Erratum: Carrasco-Sánchez, V.; et al. Removal of 4-Ethylphenol and 4-Ethylguaiacol with Polyaniline-Based Compounds in Wine-Like Model Solutions and Red Wine. Molecules 2015, 20(8), 14312-14325.

The authors wish to make the following change to their paper [1]. The Acknowledgments sectionis incorrect in the published paper. The correct Acknowledgments should be as follows:Postdoctoral Fondecyt Project 3140295, Proyecto Anillo (Integracion de la BiologiaEstructural al desarrollo de la Bionanotecnologia, ACT 1107), Innova Chile CORFO(Grant FCR-CSB 09CEII-6991), Programa de insercion y atraccion CONICYT-79090038,and PIEI-QUIBIO (UTalca) are acknowledged. A.J acknowledges FONDECYT 11130087.We apologize for any inconvenience caused to the readers by this mistake.

Cancer sniffer dogs: how can we translate this peculiarity in laboratory medicine? Results of a pilot study on gastrointestinal cancers.

Identification of cancer biomarkers to allow early diagnosis is an urgent need for many types of tumors, whose prognosis strongly depends on the stage of the disease. Canine olfactory testing for detecting cancer is an emerging field of investigation. As an alternative, here we propose to use GC-Olfactometry (GC/O), which enables the speeding up of targeted biomarker identification and analysis. A pilot study was conducted in order to determine odor-active compounds in urine that discriminate patients with gastrointestinal cancers from control samples (healthy people). Headspace solid phase microextraction (HS-SPME)-GC/MS and GC-olfactometry (GC/O) analysis were performed on urine samples obtained from gastrointestinal cancer patients and healthy controls. In total, 91 key odor-active compounds were found in the urine samples. Although no odor-active biomarkers present were found in cancer carrier's urine, significant differences were discovered in the odor activities of 11 compounds in the urine of healthy and diseased people. Seven of above mentioned compounds were identified: thiophene, 2-methoxythiophene, dimethyl disulphide, 3-methyl-2-pentanone, 4-(or 5-)methyl-3-hexanone, 4-ethyl guaiacol and phenylacetic acid. The other four compounds remained unknown. GC/O has a big potential to identify compounds not detectable using untargeted GC/MS approach. This paves the way for further research aimed at improving and validating the performance of this technique so that the identified cancer-associated compounds may be introduced as biomarkers in clinical practice to support early cancer diagnosis.

Selective production of 4-ethyl guaiacol from catalytic fast pyrolysis of softwood biomass using Pd/SBA-15 catalyst

A new technique was proposed to selectively produce 4-ethyl guaiacol (4-EG), a valuable phenolic compound, via low-temperature catalytic fast pyrolysis of softwood biomass using the Pd/SBA-15 catalyst. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments were performed to compare 4-EG production from three biomass materials with different lignin types (pine wood, poplar wood and bagasse) and two catalytic patterns (in-situ and ex-situ). Further experiments were performed to reveal 4-EG formation affected by the pyrolysis temperature, catalyst-to-biomass ratio and Pd content of the Pd/SBA-15 catalyst. The results indicated that 4-EG could be selectively produced from pine wood by the in-situ catalytic pattern. 4-EG was a very minor pyrolytic product in the non-catalytic process, while it could be selectively produced in the catalytic process, via the decomposition and hydrogenation of lignin. Our results suggested that several holocellulose-derived pyrolytic products could serve as the hydrogen-donors (H-donors) for the formation of 4-EG, without any extra H-donors. The highest 4-EG yield of 18.44mg/g from pine wood was obtained at the temperature of 350°C and catalyst-to-biomass ratio of 2, and the corresponding peak area% (calculated by GC/MS) was 38.34%.