Increasing Ethanol Concentration Research Articles

Identification of Key Parameters Inducing Microbial Modulation during Backslopped Kombucha Fermentation.

The aim of this study was to assess the impact of production parameters on the reproducibility of kombucha fermentation over several production cycles based on backslopping. Six conditions with varying oxygen accessibility (specific interface surface) and initial acidity (through the inoculation rate) of the cultures were carried out and compared to an original kombucha consortium and a synthetic consortium assembled from yeasts and bacteria isolated from the original culture. Output parameters monitored were microbial populations, biofilm weight, key physico-chemical parameters and metabolites. Results highlighted the existence of phases in microbial dynamics as backslopping cycles progressed. The transitions between phases occurred faster for the synthetic consortium compared to the original kombucha. This led to microbial dynamics and fermentative kinetics that were reproducible over several cycles but that could also deviate and shift abruptly to different behaviors. These changes were mainly induced by an increase in the Saccharomyces cerevisiae population, associated with an intensification of sucrose hydrolysis, sugar consumption and an increase in ethanol content, without any significant acceleration in the rate of acidification. The study suggests that the reproducibility of kombucha fermentations relies on high biodiversity to slow down the modulations of microbial dynamics induced by the sustained rhythm of backslopping cycles.

Dynamics in the profile of biopolymers produced by mixed microbial cultures from ethanol-rich feedstocks

The use of agro-industrial wastes as substrates for polyhydroxyalkanoate (PHA) production by mixed microbial cultures is an alternative to lower the price of these biopolymers. However, when submitting these wastes to pre-fermentation, lactate and ethanol can be produced in addition to volatile fatty acids (VFAs). In this study, the impact of ethanol on PHA storage and in the carbon flux of the process were assessed. The co-production of extracellular polymeric substances (EPS) and its impact on PHA production was investigated. PHA production yield showed a decrease from 0.92 ± 0.004–0.63 ± 0.002 Cmol-PHA.Cmol-S−1 with the increase of ethanol content from 5 to 20 Cmmol.L−1. EPS production was directly proportional to the ethanol’s fed, reaching a maximum EPS total content of 6.70 Cmmol for the maximum ethanol supplied. EPS acted as a protection strategy, which benefited PHA specific storage rate for the highest ethanol content tested. These results indicate that ethanol-rich feedstocks can be valorised through the simultaneous production of two value-added biopolymers.

Effects of Ethanol Concentrations on Primary Structural and Bioactive Characteristics of Dendrobium officinale Polysaccharides.

Ethanol fractional precipitation can initially separate polysaccharides according to the structure, which exhibits strong correlation with the biological activities. This study aimed to investigate the impact of varying ethanol concentrations on the structural characteristics, and the antitumor and antioxidant activities of polysaccharides derived from Dendrobium officinale through ethanol fractional precipitation, as well as their internal relationships. The polysaccharides acquired by absolute alcohol additions at a final liquor-ethanol volume ratio of 1:1, 1:2, and 1:4 were named DOP-1, DOP-2, and DOP-4, and the supernatant was named DOP-S. The results of the structural analysis revealed that the increase in ethanol concentrations resulted in a reduction in the molecular weights and the acetylation degree of the polysaccharides, as well as a decrease in mannose content and an increase in glucose content. In vitro experiments demonstrated that DOP-S exhibited optimal antitumor and antioxidant activities. Animal experiments further confirmed that DOP-S suppressed the growth of solid tumors significantly, enhanced lymphocytes, mediated immune ability, and improved the activity of antioxidant enzymes. These findings would establish a theoretical foundation and provide technical support for further advances and applications of polysaccharides derived from D. officinale in the fields of food and medicine.

The promoting effect of electron beam irradiation on enzymatic saccharification and alcohol fermentation of sorghum meal: Related mechanisms

In this study, sorghum meal underwent 2–10 kGy electron beam irradiation (EBI) to investigate alterations in its elemental composition, relevant physicochemical characteristics, and enzymatic hydrolysis fermentation properties. The results indicated a decrease in amylose content and an increase in reducing sugar content in sorghum meal after EBI, along with severe damage to the internal structure of starch granules, leading to increased solubility in water. Furthermore, irradiation enhanced the shear resistance and gelatinization stability of sorghum meal paste. Most importantly, EBI-induced degradation of sorghum starch molecules enhanced their susceptibility to interact with α-amylase, significantly improving the enzymatic hydrolysis and alcohol fermentation efficiency of sorghum meal. At an irradiation dose of 8 kGy, raw and cooked sorghum meal exhibited a 43.40% and 33.33% increase in ethanol concentration and a 43.44% and 30.29% increase in ethanol yield, respectively. This finding indicated that irradiation is an effective pretreatment method for starch-based ethanol fermentation.

Effects of solvent on gelation behavior and gel properties of a dihydrazide derivative organogel

ABSTRACT By introducing more polar ethanol as a co-solvent to benzene, solvent effects on gelation behavior and gel properties of N,N’-bis (4-n-alkylo-xybenzoyl) hydrazine (4D16) were investigated herein. Xerogel of 4D16 showed fiber networks in benzene, while slice aggregates in benzene/ethanol mixtures and precipitates of 4D16 in ethanol showed rod-like aggregates. XRD patterns revealed that the aggregation structure of 4D16 translated from cubic phase to lamellar phase gradually with the increase of ethanol content. FT-IR spectra showed that the H-bonding of 4D16 showing lamellar phase was stronger than that in cubic phase. Kinetics of gelation 4D16 of showed that Df value of the aggregates increased firstly and decreased afterwards (1.204→1.522→1.244). Organogel in benzene/ethanol mixtures showed higher thermostability (Tgel ) and mechanic properties with the increase of ethanol content.

A study on the solubility of some amino acids in (H2O + EtOH) and (H2O + EtOH + NaI) systems by gravimetric method at T = 298.15 K: Experimental measurements and COSMO-RS calculations

In this study, the solubility of three amino acids including glycine, L-alanine, and L-valine was measured using the gravimetric method in aqueous mixtures with 0–100 % (w/w) ethanol in different salt concentrations of sodium iodide (from 0 to 2 mol kg−1) at 298.15 K and 89.1 kPa. The Setschenow equation was used to analyze the effect of the electrolyte on solubility. In addition, the multi-parameter Kamlet-Taft (KAT) equation was applied to provide detailed information on the solute–solvent and solvent–solvent interactions. Moreover, the molecular interactions in the solvent mixture were qualitatively investigated using the COSMO-RS method. The results showed that the solubility of each amino acid increases with increasing electrolyte concentration and decreases with increasing ethanol content in the solvent mixture. The Setschenow equation and experimental solubility data showed NaI's salting-in effect in the solubility process for all amino acids. It was found that the polarity-polarizability parameter of the solvent system has the most significant effect on the solubility of the amino acids. According to the COSMO-RS calculations, glycine and solvent system favor hydrogen bonding interactions while L-alanine and L-valine tend to interact with solvent more through hydrophobic interactions.

Evaluation of Arabica Coffee Fermentation Using Machine Learning

This study explores the variances in the organic, chemical, and sensory attributes of fermented coffee beans, specifically examining how post-harvest processes influence cup quality. Coffee fruits from the Catuaí IAC-144 variety were processed using both natural coffee (NC) and pulped coffee (PC) methods. The fruits were then subjected to self-induced anaerobic fermentation (SIAF) using one of the following fermentation methods: solid-state fermentation (SSF) or submerged fermentation (SMF). Within these methods, either spontaneous fermentation (SPF) or starter culture fermentation (SCF) was applied. Each method was conducted over periods of 24, 48, and 72 h. For this purpose, two-hundred-liter bioreactors were used, along with two control treatments. Numerous parameters were monitored throughout the fermentation process. A comprehensive chemical profiling and sensory analysis, adhering to the guidelines of the Specialty Coffee Association, were conducted to evaluate the influence of these fermentation processes on the flavor, aroma, and body characteristics of the coffee beverage across multiple dimensions. Data analysis and predictive modeling were performed using machine learning techniques. This study found that NC exhibited a higher production of acids (citric, malic, succinic, and lactic) compared to PC, resulting in distinct chemical and sensory profiles. The decision tree showed that fructose and malic and succinic acids were identified as the main factors enhancing sensory notes during cupping. SMF promoted higher concentrations of lactic acid, while SSF led to increased ethanol content. Consequently, the SIAF process enhances the sensory quality of coffee, adding value to the product by generating diverse sensory profiles.

Use of an Ethanol-powered Motor-generator to Electricity Generation for Countryside Population and Small Isolated Communities

Due to the growing demand in the global energy mix and the constant concern about the use and the scarci ty of fossil fuels, the study of cleaner, cheaper, easy obtaining and environment-friendly alternative fuels has become a matter of general interest. In Brazil, the sugar cane-based ethanol is a good alternative for the use of gasoline, since the country has a land fit for cultivation of this crop, skilled labor and suitable climatic conditions, and has low emissions of greenhouse gases. In this study it was used a four-cylinder Otto-cycle engine powered by gasoline with no adjustments. It was evaluated the system performance, power, voltage, and specific fuel consump tion using mixtures of gasoline and ethanol in the follow ing proportions: E0, E5, E10, E15, E20, E30, E35, E40, E45, E50, E55, E60, E65, E70, E75, E80, E85, E90, E95 e E100. The amount of harmful exhaust gases expelled by the engine (CO2 and NOx), was also analyzed, and it was observed a reduction in the amount of CO2 expelled by the engine due to the increase of ethanol concentration in the mixture. In contrast, the amount of NOx increased due to the fact that the temperature in the combustion chamber is higher for ethanol. As a result it was observed that the motor-generator provides 800 W of power, which is enough to allow the operation of refrigerator, television and electric bulbs in a small home.

Evaluation of the effect of increasing the organic load in the thermophilic co-fermentation of sugarcane industry by-products on hydrogen, ethanol and lactic acid generation

The effects of increased organic loading rate (OLR) on H2 production and soluble metabolites in a thermophilic anaerobic fluidized bed reactor (AFBR-AT) at 55 °C were evaluated by the fermentation of vinasse and molasses from sugarcane (at a ratio of 1:1). The OLR varied between 30 and 135 kg COD.m−3.d−1, while the hydraulic retention time (HRT) was fixed at 4 h, and the initial co-substrate concentration varied between 5 and 22.5 g COD.L−1. The thermophilic acidogenic reactor showed a maximum hydrogen yield (HY) (2.49 mmol H2.g−1CODapp) at an OLR of 30 kg COD.m−3.d−1 and a higher hydrogen production rate (HPR) (2.8 L H2.L−1.d−1) at an OLR of 45 kg COD.m−3.d−1. Increasing the OLR negatively influenced H2 production. The results showed an increase in ethanol (EtOH) concentrations of up to 47.3 times and lactic acid (HLa) concentrations of up to 15.2 times when comparing OLRs of 30 and 135 kg COD.m−3.d−1, indicating changes in metabolic pathways for acid formation at organic loads ≥90 kg COD.m−3.d−1. Thermoanaerobacterium was the bacteria with higher relative abundance and was directly involved in H2 production, while Lactobacillus was mainly involved in HLa production in higher OLR, decreasing H2 production instead. Besides that, higher OLRs were favorable for sulfidogenesis and the development of sulfate-reducing bacteria, such as Desulfobacterota, due to the higher COD/sulfate ratio in OLR 135 kg COD.m−3.d−1. According to the metabolic inference in this condition, the enzyme activity of sulfite reductase and sulfite dehydrogenase may have occurred, consuming H+, thereby reducing H2 production.

Understanding the effects of ethanol on the liposome bilayer structure using microfluidic-based time-resolved small-angle X-ray scattering and molecular dynamics simulations.

Lipid nanoparticles (LNPs) are essential carrier particles in drug delivery systems, particularly in ribonucleic acid delivery. In preparing lipid-based nanoparticles, microfluidic-based ethanol injection may produce precisely size-controlled nanoparticles. Ethanol is critical in LNP formation and post-treatment processes and affects liposome size, structure, lamellarity, and drug-loading efficiency. However, the effects of time-dependent changes in the ethanol concentration on the structural dynamics of liposomes are not clearly understood. Herein, we investigated ethanol-induced lipid bilayer changes in liposomes on a time scale from microseconds to tens of seconds using a microfluidic-based small-angle X-ray scattering (SAXS) measurement system coupled with molecular dynamics (MD) simulations. The time-resolved SAXS measurement system revealed that single unilamellar liposomes were converted to multilamellar liposomes within 0.8 s of contact with ethanol, and the d-spacing was decreased from 6.1 (w/o ethanol) to 4.4 nm (80% ethanol) with increasing ethanol concentration. We conducted 1 μs MD simulations to understand the molecular-level structural changes in the liposomes. The MD simulations revealed that the changes in the lamellar structure caused by ethanol at the molecular level could explain the structural changes in the liposomes observed via time-resolved SAXS. Therefore, the post-treatment process to remove residual ethanol is critical in liposome formation.

STABILITY OF COBALT AND NICKEL COMPLEXES OF SUCCINIC AND MALEIC IONS STUDIED BY POTENTIOMETRIC TITRATION, UV-VIS SPECTROPHOTOMETRY AND QUANTUM CHEMICAL CALCULATIONS

In this study, composition and stability of coordination compounds of nickel (II) and cobalt (II) ions with succinate anion (L2-) and maleic anion (Y2-) in aqueous ethanol solutions with the molar concentration of ethanol ranging from 0.0 – 0.3 were studied by UV – Vis spectrophotometry at ionic strength of 0.1 maintained with sodium perchlorate. The result showed that, the formation of mono-ligand complexes of Ni2+ and Co2+ ions with succinate and maleic anions become stronger when the volume of ethanol rises. This may be due mainly to a change in the solvate state of the ligand with increasing ethanol concentration in the solvent. In all surveyed solvents, Co2+ forms less stable complexes than Ni2+ ion corresponding to the Irving-Williams series established for aqueous solutions. Obtained results were compared with literature data for akin compounds. The effect of solvent composition change on the geometry, charge, total electron and free Gibbs energies was studied using the DFT and MP2 levels of theory by using the Polarizable Continuum Model (PCM). The results obtained in this article by UV – Vis spectrophotometry and theoretical calculations were analyzed together with the potentiometric titration results obtained by us earlier for these complexes. The results of theoretical calculations are in good agreement with experimental data.

Degradation effects and mechanisms of Limosilactobacillus fermentum on ethanol.

Acute heavy drinking can lead to a rapid increase in blood ethanol concentration, resulting in dizziness, liver damage, and other adverse effects. Although lactic acid bacteria possess the ability to degrade ethanol, the mechanisms remain unclear. For the first time, our study revealed that Limosilactobacillus fermentum DACN611, derived from traditional Chinese fermented yogurt, exhibited superior ethanol degradation capability, achieving a 90.87% ± 8.12% reduction in ethanol concentration in a 2.5% (v/v) ethanol MRS broth over 24 h, among fifty lactic acid bacteria strains. Notably, transcriptome analysis of DACN611 under ethanol stress conditions revealed that DACN611 degraded ethanol by adjusting the cell cycle, promoting protein synthesis, maintaining oxidative metabolic homeostasis, and modulating cell wall and membrane synthesis along with other metabolic pathways. Additionally, DACN611 showed excellent resistance to gastric acid and bile salts, along with a safe profile. In the acute heavy drinking Kunming mouse model, DACN611 significantly increased the latency of the loss of righting reflex (LORR) and reduced the LORR duration. Serum ethanol and acetaldehyde concentrations decreased by 35.36% and 33.56%, respectively. The gastric and hepatic activities of alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) increased by 1.98-fold and 1.95-fold, and 1.79-fold and 1.70-fold, respectively. In addition, DACN611 decreased serum alanine aminotransferase and aspartate aminotransferase levels, and reduced hepatic cytochrome P450 2E1 expression. It also alleviated pathological liver changes, demonstrating protective effects against alcoholic liver injury in mice. In conclusion, DACN611 significantly degraded ethanol through adaptive metabolic changes under ethanol stress conditions and the promotion of ADH and ALDH activities in gastric and hepatic tissues.

Isolation and identification of yeasts from local fruits in Thua Thien Hue province, Vietnam

In this study, a total of 30 yeast isolates were recovered from local fruits in Thua Thien Hue province. Genetic characterization based on the ITS sequences identified isolates belonging to 3 species including Saccharomyces cerevisiae, Lachancea fermentati, and Clavispora fructus, with high sequence homology (over 99%) compared to published sequences in the GenBank. All identified S. cerevisiae isolates could grow well at 30°C and ferment several sugar including fructose, galactose, sucrose, mannose, maltose, and raffinose with different performances, but were inhibited at temperature higher than 35°C. The strains also grew well in the medium containing 5% ethanol (v/v) and 200 g/L glucose, but their growth ability was decreased gradually with an increase in ethanol and glucose concentrations. Interestingly, D14 strain was able to grow in the medium supplemented with 12% of ethanol, and 500 g/L of glucose at 45°C, while D7 strain could utilize both mannitol and glycerol at a low level. Our results also indicated that some strains have relatively high sedimentation efficiency, which are favorable conditions for beer fermentation and biomass recovery. The isolated yeast strains with good tolerance properties may provide a potential source of valuable raw materials for applications in beverage production and food processing.

Synthesis of Poly[N‐(2‐((3‐Morpholino‐3‐Oxopropyl)Thio)Ethyl)Methacrylamide]: A New Thermoresponsive Polymer with Tunable LCST‐ and UCST‐Type Phase Transition in Aqueous and Alcoholic Solutions

AbstractA novel monomer, N‐(2‐((3‐morpholine‐3‐isopropyl)thio)ethyl)methacrylamide (MTMA), is synthesized and polymerized by reversible addition‐fragmentation chain transfer (RAFT) polymerization to give a thermoresponsive polymer poly[N‐(2‐((3‐morpholino‐3‐oxopropyl)thio)ethyl)methacrylamide] (PMTMA). PMTMA exhibits reversible thermoresponsive phase transitions of the lower critical solution temperature (LCST) type in water and the upper critical solution temperature (UCST) type in ethanol and methanol. The degree of polymerization and concentration of PMTMA, and solvent type have a significant influence on the transition temperature. PMTMA shows complicated thermoresponse in water–alcohol mixtures. In water–ethanol mixtures, the phase diagram of PMTMA can be divided into three regions according to ethanol volume percentages, φ: 0 ≤ φ < 15% for an LCST region; 15% ≤ φ < 91.5% for a complete dissolution region; 91.5% ≤ φ ≤ 100% for a UCST region. At high water content, the LCST increases with increasing ethanol content; and at high ethanol content, the UCST decreases with increasing water content. In water–methanol mixtures, PMTMA shows more complex thermoresponse. In the range of 0–50 °C, the phase diagram can be divided into five regions, depending on the methanol volume percentages φ: 0 ≤ φ < 15% for LCST region; 15% ≤ φ < 25% for immiscible region; 25% ≤ φ < 85% for UCST region; 85% ≤ φ < 95% for fully dissolved region; 95% ≤ φ ≤ 100% for another UCST region.

Startup operation of an energetically-intensified single-tube type falling film distillation column: Insights from a pilot-scale study

Technological advancements in the field of energetically intensified falling film distillation columns have not been paralleled by sufficient published research on comparative startup evaluations for the single-tube falling film distillation column under different thermal energy transfer methods. The present study's originality and significance stem from presenting a startup procedure for a single-tube type falling film distillation column that employs a biphasic thermosyphon as a heat source for producing hydrated ethanol at a pilot scale. The concept of three discrete phases, the discontinuous, semi-continuous, and continuous phases, was employed to characterize the startup operation. The time and energy required for each phase of the startup operation were determined. This study also examined the startup operation with respect to two possible thermal energy transfer methods from the steam chamber to the distillation tube: isothermal and non-isothermal. The experiments were conducted in a pilot distillation column consisting of a single vertical tube, which processed a binary mixture of water and ethanol with a flow rate of 33 kg h−1. No relevant variation in startup time was detected for the three distinct stages when comparing the two heating modes, with a total startup duration of 2.2 h being observed irrespective of the heating configuration utilized. The isothermal heating configuration can produce hydrated ethanol at a rate of 3.0 kg h−1, with an ethanol content increase from 12.5 to 62.8 wt%. However, the non-isothermal heating mode yields a higher ethanol content an increase in ethanol content from 12.5 to 64.3 wt.%, albeit with a lower productivity rate of 1.3 kg h−1. Operating the single-tube type falling film distillation column with the steam chamber under the non-isothermal heating mode required only 2.12 kW for the startup, resulting in a 30.30 % reduction in energy demand compared to the isothermal heating configuration. The presented findings provide an empirical foundation for improving the efficiency and effectiveness of energetically intensified falling film distillation columns.

Synthesis of Pd-Cu/TPPCu electrocatalyst for direct ethanol fuel cell applications

In this study, the electro-oxidation reaction of ethanol over Pd–Cu supported on Cu porphyrin (TPPCu) was investigated. The catalyst was synthesized using the microwave-assisted polyol method and physicochemically characterized by XRD, XPS, SEM, EDS, TEM, EDAX, UV–Vis, FTIR, and RBS. A Cu-enriched catalyst with Cu3Pd, Pd,Cu, and TPPCu phases was identified using XRD and XPS. However, according to the RBS results, the catalytic surface was enriched with Pd, indicating that the interaction between TPPCu and Pd–Cu allowed the presence of Pd on the surface, thus enhancing the catalytic response of the material. This synthesis prevented the deprotonation of porphyrin on the electrocatalyst, as confirmed by XPS analysis. Electrochemical studies based on cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate the response of the catalyst to variations in the scan rate and increasing ethanol concentration. The electrochemical response of PdCu/TPPCu improved with an increasing number of cycles, indicating improved mass transport, thus improving its electrochemical response and tolerance to CO contamination. This catalyst exhibited a high electroactive surface area of 49.4 m2/g, which could be related to the presence of TPPCu as a support. The behavior of the catalyst on the anode of a fuel cell fed with ethanol, bioethanol, and bioethanol residues was evaluated.Graphical

Effect of inoculum size and agitation speed on bioethanol production by Kluyveromyces marxianus using sugarcane molasse

In this study, bioethanol production was carried out at a high temperature (40 0C) using Kluyveromyces marxianus in sugar cane molasses media with a study of combinations in fermentation conditions in the form of inoculum concentration and agitation speed. This study investigated the effect of inoculum concentration and agitation speed on bioethanol production. This study used a factorial randomized block design with two factors: inoculum concentration (with levels of 5%, 10%, and 15% (v/v)) and agitation speed (with levels of 100, 150, and 200 rpm). The results showed that the interaction of inoculum concentration and agitation speed significantly decreased pH, total sugar consumption, total reducing sugar (TRS) consumption, and total dissolved solids (TDS). However, an increase in cell optical density (OD), ethanol concentration, and ethanol yields was evident from all treatments. The best treatment was from a combination of 10% inoculum with an agitation speed of 150 rpm, giving the highest ethanol concentration of 3.44% and ethanol yields of 89.91%.

Transcriptomic and metabonomic to evaluate the effect mechanisms of the growth and aroma-producing of Pichia anomala under ethanol stress

Ethanol stress is an important environmental factor that affects physiological metabolism and aroma-producing capacity of yeast during the brewing process of alcoholic products. To explore the mechanisms of the growth and aroma-producing metabolism of Pichia anomala under ethanol stress, transcriptomic and metabolomic results were collected from different concentrations (3%, 6% and 9%) of the ethanol stressor, and genes, metabolites and metabolic pathways that relate to growth and aroma-producing were screened. Integrated transcriptomic and metabolomic results showed that P. anomala could respond to ethanol stress by activating purine and pyrimidine, glycerophospholipid and antioxidant metabolic pathways. However, the damage to the growth of P. anomala under ethanol stress was closely related to the inhibition of carbohydrate metabolism, ABC transporter, energy metabolism and amino acid pathways, the influence on these pathways became more serious with the increase of ethanol concentrations. Meantime, the decrease in production of phenethyl alcohol and isoamyl alcohol was related to the significantly down-regulated of ARO9, ARO10, ADH1 and ADH2 genes expression in phenylalanine, tyrosine and tryptophan, and glycolysis pathways of P. anomala under ethanol stress. The enhanced expression of ATF1, EAT1, EEB1 and TGL2 genes in P. anomala was the main reason for the high yield of ethyl caproate and ethyl acetate under ethanol stress. These results revealed a theoretical basis for further study of the effect mechanisms of ethanol stress on P. anomala and molecular targets for the construction of genetic engineering strains with high ethanol tolerance and high aroma production.

Lyso-phosphatidylethanol detected by LC-MS/MS as a potential new marker for alcohol consumption.

Alcohol biomarkers are able to reflect the degree of recent or long-term alcohol consumption, covering different windows of detection. Phosphatidylethanols (PEths) are an emerging group of direct alcohol biomarkers that are widely applied in clinical and forensic applications. Their quantification can provide insight into an individual's drinking behaviour. Here, we present a new sub-class of yet unknown PEth species, LysoPEths, which are structurally related to PEth, but miss one fatty acyl chain. LysoPEths can be either a degradation product of PEth or a product of transesterification of lyso-phosphatidylcholine (LysoPC) with ethanol. To set up an analytical method, LysoPEth 16:0 was synthesised from PC 16:0/18:1 and characterised by LC-MS/MS, using an enzymatic method: phospholipase D (PLD), followed by phospholipase A2 (PLA2). Then, an LC-MS/MS method in MRM mode for LysoPEth 16:0 with additional LysoPEth species (LysoPEth 18:1, LysoPEth 18:2, and LysoPEth 20:4) and PEth 16:0/20:4 was developed. By incubation of freshly sampled venous blood of a teetotaller with ethanol at different concentrations, the formation of LysoPEth in parallel to PEth was investigated. With increasing ethanol concentrations, LysoPEth 16:0 was formed besides the known PEth species (PEth 16:0/18:1, PEth 16:0/18:2) for up to 72 h with LysoPEth concentrations being about three times lower than PEth concentrations. Storage of ethanol-free PEth-positive blood of an alcohol consumer at 37 °C showed that LysoPEth 16:0 concentrations increased, while PEth 16:0/18:1 concentrations decreased in the first 24 h for frozen/thawed blood, however not for freshly collected blood. Furthermore, LysoPEth 16:0 was detected in venous as well as lyophilised blood from clinical and forensic case work alongside with PEth 16:0/18:1, 16:0/18:2, and other PEth and LysoPEth species (PEth 16:0/20:4, LysoPEth 18:1, LysoPEth 18:2, and LysoPEth 20:4). LysoPEth 16:0 concentrations were found to be in linear correlation with PEth 16:0/18:1 (r2 = 0.75).

Study on the mechanism on synthesis of higher alcohols in Wickerhamomyces anomalus under ethanol stress

AbstractHigher alcohols (phenylethyl alcohol and isoamyl alcohol), as the crucial aroma compounds, have been found to associate with the sensory properties of various alcoholic products. The Ehrlich and Harris pathways are the main pathways for yeast to produce phenylethyl alcohol and isoamyl alcohol during the brewing process of alcoholic products, whereas the specific changes of the Ehrlich and Harris pathways in Wickerhamomyces anomalus under ethanol stress are still unclear. In this study, W. anomalus NCU003 with a high capacity for aroma compound production was treated with ethanol stress at different concentrations (3%, v/v, 6%, v/v and 9%, v/v) to study the effects on the expression levels of genes and metabolite content in the Ehrlich and Harris pathways. The results found that ethanol stress inhibited the production of phenylethyl alcohol and isoamyl alcohol, and the content decreased with the increase of ethanol concentrations. In the meantime, the up‐regulation of ARO1, CS, ARO8, Leu1, BAT2 and ilvs family genes in the Ehrlich and Harris pathways could lead to an increase in the synthesis of important precursor substances during the synthesis of phenylethyl alcohol and isoamyl alcohol. However, the significant down‐regulation of ARO10, PDC, ADH1 and AHD2 genes was the main reason for the low production of phenylethyl alcohol and isoamyl alcohol. These results could provide a theoretical reference for the construction of genetic engineering strains of W. anomalus in the future so as to reasonably control the content of higher alcohols during the brewing process of alcoholic products.